Fast Solution Blow Spinning of Lotus-Leaf-Inspired SiO2 Nanofiber Sponge for High Efficiency Purification

Massive production of SiO2 nanofibers with both high durability and exceptional performance remains a significant challenge. Herein, a novel approach was introduced to achieve the massive production of SiO2 nanofibers with lotus-leaf-inspired surfaces by combining solution blowing spinning (SBS) and the polymer-derived ceramics method. Based on the SBS technique, three types of precursor nanofiber products were fast spined with methyl silsesquioxane polymer and polymethyl hydrogen siloxane employed as Si sources. The flow rate of the SBS spined Si-based ceramic nanofibers was enhanced to 20 mL·h-1. Furthermore, through the integration of hydrophobic-oleophilic SiO2 nanoparticles into the precursor solution, SiO2 nanofibers with lotus-leaf nanoprotrusion surfaces were fabricated. Nanoparticle-decorated SiO2 fibers demonstrated excellent hydrophobicity (138.3°), compression resilience (∼60%), proficiency in organic pollutant adsorption, high-temperature resistance (∼1100 °C), and outstanding thermal insulation properties (thermal conductivity of 0.0165 W·(m·K)-1).

Gamma radiation-induced grafting of poly(butyl acrylate) onto ethylene vinyl acetate copolymer for improved crude oil flowability

Ethylene vinyl acetate (EVA) copolymers are widely employed as pour point depressants to enhance the flow properties of crude oil. However, EVA copolymers have limitations that necessitate their development. This work investigated the modification of EVA via gamma radiation-induced grafting of butyl acrylate (BuA) monomers and the evaluation of grafted EVA as a pour point depressant for crude oil. The successful grafting of poly(butyl acrylate) p(BuA) onto EVA was verified through grafting parameters, FTIR spectroscopy, and 1H NMR spectroscopy. Treating crude oil with 3000 ppm of (EVA)0kGy, (EVA)50kGy, and (1EVA:3BuA)50kGy yielded substantial reductions in pour point of 24, 21, and 21 °C, respectively. Also, rheological characterization demonstrated improving evidenced by a viscosity reduction of 76.20%, 67.70%, and 71.94% at 25 °C, and 83.16%, 74.98%, and 81.53% at 12 °C. At low dosages of 1000 ppm, the EVA-g-p(BuA) exhibited superior pour point reductions compared to unmodified EVA, highlighting the benefit of incorporating p(BuA) side chains. The grafted EVA copolymers with p(BuA) side chains showed excellent potential as crude oil flow improvers by promoting more effective adsorption and co-crystallization with paraffin wax molecules.

Bioreducible Amphiphilic Hyperbranched Polymer-Drug Conjugate for Intracellular Drug Delivery

This paper reports synthesis of a bioreducible hyperbranched (HB) polymer by A2+B3 approach from commercially available dithiothreitol (DTT) (A2) and an easily accessible trifunctional monomer (B3) containing three reactive pyridyl-disulfide groups. Highly efficient thiol-activated disulfide exchange reaction leads to the formation of the HB polymer (Mw = 21000; Đ = 2.3) with bioreducible disulfide linkages in the backbone and two different functional groups, namely, hydroxyl and pyridyl-disulfide in the core and periphery, respectively, of the HB-polymer. Postpolymerization functionalization of the hydroxyl-groups with camptothecin (CPT), a topoisomerase inhibitor and known anticancer drug, followed by replacing the terminal pyridyl-disulfide groups with oligo-oxyethylene-thiol resulted in easy access to an amphiphilic HB polydisulfide-CPT conjugate (P1) with a very high drug loading content of ∼40%. P1 aggregated in water (above ∼10 μg/mL) producing drug-loaded nanoparticles (Dh ∼ 135 nm), which showed highly efficient glutathione (GSH)-triggered release of the active CPT. Mass spectrometry analysis of the GSH-treated P1 showed the presence of the active CPT drug as well as a cyclic monothiocarbonate product, which underpins the cascade-degradation mechanism involving GSH-triggered cleavage of the labile disulfide linkage, followed by intramolecular nucleophilic attack by the in situ generated thiol to the neighboring carbonate linkage, resulting in release of the active CPT drug. The P1 nanoparticle showed excellent cellular uptake as tested by confocal fluorescence microscopy in HeLa cells by predominantly endocytosis mechanism, resulting in highly efficient cell killing (IC50 ∼ 0.6 μg/mL) as evident from the results of the MTT assay, as well as the apoptosis assay. Comparative studies with an analogous linear polymer-CPT conjugate showed much superior intracellular drug delivery potency of the hyperbranched polymer.

Photoresponsive Viscoelasticity of the Granular Materials of Azobenzene-Bearing Molecular Nanoparticles

The large sizes of granular particles lead to their slow diffusive dynamics and significant interparticle friction, bringing enormous difficulty to tune the mechanical properties and processability of the granular materials (GMs). Herein, 1 nm polyhedral oligomeric silsesquioxane (POSS) particles functionalized with azobenzene are designed as structural units, and the obtained GMs show unique photoswitchable viscoelasticity. The azobenzene group can undergo a reversible trans-cis conformation switch while the π-π stacking among the azobenzene fragments is only favored by the trans-conformation due to molecular geometrical requirements. The POSS units from neighboring assemblies close pack to form microdomains, and the POSS is under confinement by both the supramolecular bonding and the other POSS in the microdomains. The simultaneous breaking of the two types of confinement is difficult and, therefore, the free diffusion of POSS is hindered, leading to the elasticity of the GMs of trans-POSS. For cis-POSS, the interparticle supramolecular interaction is weak and the POSS unit can undergo free diffusion, contributing to their high flowability at room temperature. The photoswitching viscoelasticity of GMs is further used for self-healing and photoswitchable adhesion. This work paves new pathways for the regulation of material viscoelasticity and the design of GM-based smart materials.

New Approach for Preparation of Porous Polymers with Reversible Pore Structures for a Highly Safe Smart Supercapacitor

Porous polymers have many industrial applications, but their pore structures (open or closed) are usually fixed during polymerization. In this study, polymers with reversible and controllable pore structures, namely, thermosensitive porous hydrogels with regulated volume phase transition temperature, were prepared using a Pickering high-internal-phase emulsion as the template. Upon heating, the hydrogels transformed not only in their wettability (between hydrophilicity and hydrophobicity with water contact angles of 21.8 and 100.9°) but also their pore structure (between open through-holes and closed holes with pore throat sizes of 15.58 and 0 μm, respectively) in a short time (<10 s). When the hydrogel was used as a separator in smart supercapacitors (SCs), this behavior effectively limited the path of electrolyte migration, reducing the chance of conflagration accidents. Moreover, by utilizing the highly reversible pore structures and wettability of the porous hydrogel, reversible charging and discharging were restored after the system cooled down. This work not only provides great guidance for preparing porous polymers with reversible pore structures but also paves the way for designing smart SCs with enhanced safety.

Facial Skin Rejuvenation Using Poly-dl-Lactic Acid Injected With a Laser-Generated Needle-Free Microjet Injector

BACKGROUND

A laser-induced needle-free microjet injector was developed for rapid, high-speed drug delivery of microliters into the skin.

OBJECTIVE

This study evaluated the clinical rejuvenation effect of repeated dermal injections of the collagen simulator poly-dl-lactic acid (PDLA) using a laser-induced needle-free microjet injector.

METHODS

Five PDLA injection sessions using a laser-induced needle-free microjet injector were conducted in patients concerned about aging skin. Facial uplifting, darkness, redness, roughness, pore size, subjective satisfaction, and side effects were evaluated before each session and 4 weeks after treatment completion. Histological evaluation was also performed with immunohistochemical staining of collagen and elastic fibers.

RESULTS

The clinical results of 27 female patients were evaluated. The treatment resulted in a noticeable skin surface uplifting (0.711 ± 0.42 mm) and significant improvements in darkness (p = .013), redness (p = .009), and roughness (p = .036), with no significant difference in the pore size (p = .770). Patients were reported being satisfied with the overall therapeutic effects, despite mild and tolerable adverse effects. Histological findings revealed growth and thickening of collagen and elastic fibers, with marked increase in collagen I and III levels.

CONCLUSION

Repeated dermal injections of PDLA using a laser-induced microjet injector offer excellent drug delivery, achieving high efficacy in skin rejuvenation, patient satisfaction, and safety.

Raman Characterization of Plastics: A DFT Study of Polystyrene

Plastic materials are ubiquitous and raise concerns about their impact on health and the environment. To address these concerns, it is crucial to characterize the structural, size, and textural properties of plastics throughout their lifecycle from production to degradation. Raman spectroscopy appears as a valuable tool for this purpose, offering speed, robustness, and sensitivity to nanoscale and amorphous particles. In order to be properly used for plastics, the Raman response of reference materials needs to be carefully assessed, with the literature on such assessments being scarce. This study addresses this gap by using theoretical calculations to generate ab initio spectra for polystyrene, a reference material. The aim is to explain the origins of the spectral peaks and their consistency across various compositions and structures using linear ordered polymeric and finite amorphous models. The CRYSTAL package is employed to obtain full Raman spectra based on a careful benchmark of computational settings. While some peaks are present across all spectra and can serve for calibration, others exhibit structure-dependent behavior, enabling polymer identification. We conclude that Raman spectroscopy is a well-suited technique for plastics characterization provided that a careful analysis of signal origin is conducted to fully interpret the spectra and deploy applications.

Ligand-Dominated Activation of CO2 and CS2 by the Putative Nickel Phosphiniminato Intermediates

Room-temperature photoactivation of the first- and second-generation PN3P-pincer nickel azido complexes 1a and 1b in the presence of CO2 or CS2 afforded N-bound carbamates, dithiocarbamates, and isothiocyanates, providing insights into CO2 and CS2 activation and demonstrating how a seemingly small difference in the ligand structure significantly influences the reactivity. Theoretical calculations disclosed that the charge of the phosphorus atom plays a critical role in determining the nitrogen atom transfer to form a plausible nickel phosphiniminato intermediate.

A density functional study of the photocatalytic degradation of polycaprolactone by the decatungstate anion in acetonitrile solution

A recent experimental study has reported that decatungstate [W10O32]4- can degrade various polyesters in the presence of light and molecular oxygen [Li et al., Nanoscale, 2023, 15, 15038]. We apply density functional theory to the photocatalyst-polycaprolactone model complex in acetonitrile solution and elucidate the degradation mechanisms and catalytic cycle. We consider hydrogen atom transfer (HAT) and single electron transfer (SET) mechanisms. The potential energy profiles show that the former proceeds exergonically in a single step but that the latter involves a subsequent proton transfer and finally yields HAT products as well. Oxygenated polymer species can regain the transferred hydrogen and regenerate the reduced photocatalyst. We propose a photocatalytic cycle that realizes both the photocatalyst regeneration and the polymer degradation.

Thermodynamic model for voltammetric responses in conducting redox polymers

Electroactive polymer materials are known to play important roles in a vast spectrum of modern applications such as in supercapacitors, fuel cells, batteries, medicine, and smart materials, etc. They are usually divided into two main groups: first, conducting π-conjugated organic polymers, which conduct electricity by cation-radicals delocalized over a polymer chain; second, redox polymers, which conduct electricity via an electron-hopping mechanism. Polymer materials belonging to these two main groups have been thoroughly studied and their thermodynamic and kinetic models have been built. However, in recent decades a lot of mixed-type materials have been discovered and investigated. To the best of our knowledge, a thermodynamic-based description of conducting redox polymers (CRPs) has not been provided yet. In this work, we present a thermodynamic model for voltammetric responses of conducting redox polymers. The derived model allows one to extract thermodynamic parameters of a CRP including the polaron delocalization degree and redox active groups interaction constant. The model was verified with voltammetric experiments on three recently synthesized CRPs and showed a satisfactory predictive ability. The simulated data are in good agreement with the experiment. We believe that developing theoretical descriptions for CRPs and other types of electroactive materials with the ability to simulate their electrochemical responses may help in future realization of new systems with superior characteristics for electrochemical energy storage, chemical sensors, pharmacological applications, etc.

Phosphine-Capped Effects Enable Full-Color Clusteroluminescence in Nonconjugated Polyesters

Full-color luminophores have advanced applications in materials and engineering, but constructing color-tunable clusteroluminescence (CL) from nonconjugated polymers based on through-space interactions remains a huge challenge. Herein, we develop phosphine-capped nonconjugated polyesters exhibiting blue-to-red CL (400-700 nm) based on phosphine-initiated copolymerization of epoxides and cyclic anhydrides, especially P1-0.5TPP, which exhibits red CL (610 nm) with a high quantum yield of 32%. Experiments and theoretical calculations disclose that the phosphine-capped effect in polyesters brings about conformational changes and induces phosphine-ester clusters by through-space (n,π*) interactions. Moreover, CL colors and efficiencies can be easily tailored by types of phosphines, compositions and structures of polyesters, and concentration. Significantly, the role of polymer motions (group, segmental, and chain motions) on CL originating from microregions inside polyesters is revealed. Further, phosphine-capped nonconjugated polyesters are demonstrated to be nonconjugated dyes and fluorescent fibers and are also used for multicolor light-emitting diodes including white light. This work not only provides an engineering strategy based on the end-group effect to prepare full-color clusteroluminogens but also broadens the prospects for material applications.

Bioinspired and biomimetic strategies for inflammatory bowel disease therapy

Inflammatory bowel disease (IBD) is an idiopathic chronic inflammatory bowel disease with high morbidity and an increased risk of cancer or death, resulting in a heavy societal medical burden. While current treatment modalities have been successful in achieving long-term remission and reducing the risk of complications, IBD remains incurable. Nanomedicine has the potential to address the high toxic side effects and low efficacy in IBD treatment. However, synthesized nanomedicines typically exhibit some degree of immune rejection, off-target effects, and a poor ability to cross biological barriers, limiting the development of clinical applications. The emergence of bionic materials and bionic technologies has reshaped the landscape in novel pharmaceutical fields. Biomimetic drug-delivery systems can effectively improve biocompatibility and reduce immunogenicity. Some bioinspired strategies can mimic specific components, targets or immune mechanisms in pathological processes to produce targeting effects for precise disease control. This article highlights recent research on bioinspired and biomimetic strategies for the treatment of IBD and discusses the challenges and future directions in the field to advance the treatment of IBD.

Cellulose, cellulose derivatives and cellulose composites in sustainable corrosion protection: challenges and opportunities

The use of cellulose-based compounds in coating and aqueous phase corrosion prevention is becoming more popular because they provide excellent protection and satisfy the requirements of green chemistry and sustainable development. Cellulose derivatives, primarily carboxymethyl cellulose (CMC) and hydroxyethyl cellulose (HEC), are widely employed in corrosion prevention. They function as efficient inhibitors by adhering to the metal's surface and creating a corrosion-inhibitive barrier by binding using their -OH groups. Their inhibition efficiency (%IE) depends upon various factors, including their concentration, temperature, chemical composition, the nature of the metal/electrolyte and availability of synergists (X-, Zn2+, surfactants and polymers). Cellulose derivatives also possess potential applications in anticorrosive coatings as they prevent corrosive species from penetrating and encourage adhesion and cohesion, guaranteeing the metal substrate underneath long-term protection. The current review article outlines the developments made in the past and present to prevent corrosion in both the coating phase and solution by using cellulose derivatives. Together with examining the difficulties of the present and the prospects for the future, the corrosion inhibition mechanism of cellulose derivatives in the solution and coating phases has also been investigated.

Drug eluting protein and polysaccharides-based biofunctionalized fabric textiles- pioneering a new frontier in tissue engineering: An extensive review

In the ever-evolving landscape of tissue engineering, medicated biotextiles have emerged as a game-changer. These remarkable textiles have garnered significant attention for their ability to craft tissue scaffolds that closely mimic the properties of natural tissues. This comprehensive review delves into the realm of medicated protein and polysaccharide-based biotextiles, exploring a diverse array of fabric materials. We unravel the intricate web of fabrication methods, ranging from weft/warp knitting to plain/stain weaving and braiding, each lending its unique touch to the world of biotextiles creation. Fibre production techniques, such as melt spinning, wet/gel spinning, and multicomponent spinning, are demystified to shed light on the magic behind these ground-breaking textiles. The biotextiles thus crafted exhibit exceptional physical and chemical properties that hold immense promise in the field of tissue engineering (TE). Our review underscores the myriad applications of drug-eluting protein and polysaccharide-based textiles, including TE, tissue repair, regeneration, and wound healing. Additionally, we delve into commercially available products that harness the potential of medicated biotextiles, paving the way for a brighter future in healthcare and regenerative medicine. Step into the world of innovation with medicated biotextiles-where science meets the art of healing.

The design of an RGD in situ sustained delivery system utilizing scallop byssal protein through genetic engineering

Although bioactive peptides enhancing bone healing have demonstrated effectiveness in treating bone defects, in vivo instability poses a challenge to their clinical application. Currently reported peptide delivery systems do not meet the demands of bone tissue repair regarding stability and peptide release efficacy. Herein, the self-assembling recombinant chimeric protein (Sbp5-2RGD) is developed by genetic engineering with cell adhesion peptide RGD as the targeted peptide and a newly discovered scallop byssal-derived protein Sbp5-2 that can assemble into wet stable films as the structural domain. In vitro studies show that the Sbp5-2RGD film exhibits excellent extensibility and biocompatibility. In vitro and in vivo degradation experiments demonstrate that the film remains stable due to the layer-by-layer degradation mode, resulting in sustained delivery of RGD in situ for up to 4 weeks. Consequently, the film can effectively promote osteogenesis, which accelerates bone defect healing and the implants osseointegration. Cell-level studies further show that the film up-regulates the expression of genes and proteins (ALP, OCN, OSX, OPN, RUNX2, VEGF) associated with osteogenesis and angiogenesis. Overall, this novel protein film represents an intelligent platform for peptide immobilization, protection, and release through its self-assembly, dense structure, and degradation mode, providing a therapeutic strategy for bone repair.

The study of double-network carboxymethyl chitosan/sodium alginate based cryogels for rapid hemostasis in noncompressible hemorrhage

Developing an injectable hemostatic dressing with shape recovery and high blood absorption ratio for rapid hemostasis in noncompressible hemorrhage maintains a critical clinical challenge. Here, double-network cryogels based on carboxymethyl chitosan, sodium alginate, and methacrylated sodium alginate were prepared by covalent crosslinking and physical crosslinking, and named carboxymethyl chitosan/methacrylated sodium alginate (CM) cryogels. Covalent crosslinking was achieved by methacrylated sodium alginate in the freeze casting process, while physical crosslinking was realized by electrostatic interaction between the amino group of carboxymethyl chitosan and the carboxyl group of sodium alginate. CM cryogels exhibited large water swelling ratios (8167 ± 1062 %), fast blood absorption speed (2974 ± 669 % in 15 s), excellent compressive strength (over 160 kPa for CM100) and shape recovery performance. Compared with gauze and commercial gelatin sponge, better hemostatic capacities were demonstrated for CM cryogel with the minimum blood loss of 40.0 ± 8.9 mg and the lowest hemostasis time of 5.0 ± 2.0 s at hemostasis of rat liver. Made of natural polysaccharides with biocompatibility, hemocompatibility, and cytocompatibility, the CM cryogels exhibit shape recovery and high blood absorption rate, making them promising to be used as an injectable hemostatic dressing for rapid hemostasis in noncompressible hemorrhage.

A comprehensive review on processing, characteristics, and applications of cellulose nanofibrils/graphene hybrid-based nanocomposites: Toward a synergy between two-star nanomaterials

Nanostructured materials are fascinating since they are promising for intensely enhancing materials' performance, and they can offer multifunctional features. Creating such high-performance nanocomposites via effective and mild approaches is an inevitable requirement for sustainable materials engineering. Nanocomposites, which combine two-star nanomaterials, namely, cellulose nanofibrils (CNFs) and graphene derivatives (GNMs), have recently revealed interesting physicochemical properties and excellent performance. Despite numerous studies on the production and application of such systems, there is still a lack of concise information on their practical uses. In this review, recent progress in the production, modification, properties, and emerging uses of CNFs/GNMs hybrid-based nanocomposites in various fields such as flexible energy harvesting and storage, sensors, adsorbents, packaging, and thermal management, among others, are comprehensively examined and described based on recent investigations. Nevertheless, numerous challenges and gaps need to be addressed to successfully introduce such nanomaterials in large-scale industrial applications. This review will certainly help readers understand the design approaches and potential applications of CNFs/GNMs hybrid-based nanocomposites for which new research directions in this emerging topic are discussed.

Insights into heterogeneous surface induced bubble nucleation mechanisms in cellulose reinforced polylactic acid foams

As the most abundant natural homo-polymer, cellulose has the potential to enhance polymer properties reducing the cost of raw materials. In this work, the carboxylate cellulose nanofiber (CNF-C) was selected to modify polylactic acid (PLA) foams, and the density functional theory was constructed to help analyze the foaming mechanism quantitatively. The theoretical results showed that the ordered structure, the carboxyl and the hydroxyl of CNF-C were more conducive to providing much stronger CO2 adsorption for bubble nucleation, where the predicted critical bubble size decreased and the cell density increased with the content of CNF-C. The experimental results revealed that the CNF-C promoted the rheological properties and crystallization behaviors of PLA samples, the PLA/CNF-C foams were characterized with uniform structures, the average cell size decreased from 21.39 μm to 0.19 μm, and the cell number density increased from 2.65×1010cell/cm3 to 2.30×1014cell/cm3. Those improvements resulted in an increase of 394.0 % for the compressive strength of the prepared foams. Generally, the high-performance PLA/CNF-C foams were fabricated successfully without compromising the properties of bio-based and biodegradable, the foaming mechanism was analyzed combining theoretical results with experimental data, and it was believed to provide a guide for cellulose reinforcing biodegradable polymer materials.

Metagenomic investigations into the microbial consortia, degradation pathways, and enzyme systems involved in the biodegradation of plastics in a tropical lentic pond sediment

The exploitation of exciting features of plastics for diverse applications has resulted in significant plastic waste generation, which negatively impacts environmental compartments, metabolic processes, and the well-being of aquatic ecosystems biota. A shotgun metagenomic approach was deployed to investigate the microbial consortia, degradation pathways, and enzyme systems involved in the degradation of plastics in a tropical lentic pond sediment (APS). Functional annotation of the APS proteome (ORFs) using the PlasticDB database revealed annotation of 1015 proteins of enzymes such as depolymerase, esterase, lipase, hydrolase, nitrobenzylesterase, chitinase, carboxylesterase, polyesterase, oxidoreductase, polyamidase, PETase, MHETase, laccase, alkane monooxygenase, among others involved in the depolymerization of the plastic polymers. It also revealed that polyethylene glycol (PEG), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polyethylene terephthalate (PET), and nylon have the highest number of annotated enzymes. Further annotation using the KEGG GhostKOALA revealed that except for terephthalate, all the other degradation products of the plastic polymers depolymerization such as glyoxylate, adipate, succinate, 1,4-butanediol, ethylene glycol, lactate, and acetaldehyde were further metabolized to intermediates of the tricarboxylic acid cycle. Taxonomic characterization of the annotated proteins using the AAI Profiler and BLASTP revealed that Pseudomonadota members dominate most plastic types, followed by Actinomycetota and Acidobacteriota. The study reveals novel plastic degraders from diverse phyla hitherto not reported to be involved in plastic degradation. This suggests that plastic pollution in aquatic environments is prevalent with well-adapted degrading communities and could be the silver lining in mitigating the impacts of plastic pollution in aquatic environments.

Advances in guided bone regeneration membranes: a comprehensive review of materials and techniques

Guided tissue/bone regeneration (GTR/GBR) is a widely used technique in dentistry to facilitate the regeneration of damaged bone and tissue, which involves guiding materials that eventually degrade, allowing newly created tissue to take its place. This comprehensive review the evolution of biomaterials for guided bone regeneration that showcases a progressive shift from non-resorbable to highly biocompatible and bioactive materials, allowing for more effective and predictable bone regeneration. The evolution of biomaterials for guided bone regeneration GTR/GBR has marked a significant progression in regenerative dentistry and maxillofacial surgery. Biomaterials used in GBR have evolved over time to enhance biocompatibility, bioactivity, and efficacy in promoting bone growth and integration. This review also probes into several promising fabrication techniques like electrospinning and latest 3D printing fabrication techniques, which have shown potential in enhancing tissue and bone regeneration processes. Further, the challenges and future direction of GTR/GBR are explored and discussed.

Deciphering the Microdroplet Acceleration Factors of Aza-Michael Addition Reactions

Microdroplet chemistry is emerging as a great tool for accelerating reactions by several orders of magnitude. Several unique properties such as extreme pHs, interfacial electric fields (IEFs), and partial solvation have been reported to be responsible for the acceleration; however, which factor plays the key role remains elusive. Here, we performed quantum chemical calculations to explore the underlying mechanisms of an aza-Michael addition reaction between methylamine and acrylamide. We showed that the acceleration in methanol microdroplets results from the cumulative effects of several factors. The acidic surface of the microdroplet plays a dominating role, leading to a decrease of ∼9 kcal/mol in the activation barrier. We speculated that the dissociation of both methanol and trace water contributes to the surface acidity. An IEF of 0.1 V/Å can further decrease the barrier by ∼2 kcal/mol. Partial solvation has a negligible effect on lowering the activation barrier in microdroplets but can increase the collision frequency between reactants. With acidity revealed to be the major accelerating factor for methanol droplets, reactions on water microdroplets should have even higher rates because water is more acidic. Both theoretically and experimentally, we confirmed that water microdroplets significantly accelerate the aza-Michael reaction, achieving an acceleration factor that exceeds 107. This work elucidates the multifactorial influences on the microdroplet acceleration mechanism, and with such detailed mechanistic investigations, we anticipate that microdroplet chemistry will be an avenue rich in opportunities in the realm of green synthesis.

Biomimetic Mineralized 3D-Printed Polycaprolactone Scaffold Induced by Self-Adaptive Nanotopology to Accelerate Bone Regeneration

Three-dimensional (3D)-printed biodegradable polymer scaffolds are at the forefront of personalized constructs for bone tissue engineering. However, it remains challenging to create a biological microenvironment for bone growth. Herein, we developed a novel yet feasible approach to facilitate biomimetic mineralization via self-adaptive nanotopography, which overcomes difficulties in the surface biofunctionalization of 3D-printed polycaprolactone (PCL) scaffolds. The building blocks of self-adaptive nanotopography were PCL lamellae that formed on the 3D-printed PCL scaffold via surface-directed epitaxial crystallization and acted as a linker to nucleate and generate hydroxyapatite crystals. Accordingly, a uniform and robust mineralized layer was immobilized throughout the scaffolds, which strongly bound to the strands and had no effect on the mechanical properties of the scaffolds. In vitro cell culture experiments revealed that the resulting scaffold was biocompatible and enhanced the proliferation and osteogenic differentiation of mouse embryolous osteoblast cells. Furthermore, we demonstrated that the resulting scaffold showed a strong capability to accelerate in vivo bone regeneration using a rabbit bone defect model. This study provides valuable opportunities to enhance the application of 3D-printed scaffolds in bone repair, paving the way for translation to other orthopedic implants.

An enzymatic continuous-flow reactor based on a pore-size matching nano- and isoporous block copolymer membrane

Continuous-flow biocatalysis utilizing immobilized enzymes emerged as a sustainable route for chemical synthesis. However, inadequate biocatalytic efficiency from current flow reactors, caused by non-productive enzyme immobilization or enzyme-carrier mismatches in size, hampers its widespread application. Here, we demonstrate a general-applicable and robust approach for the fabrication of a high-performance enzymatic continuous-flow reactor via integrating well-designed scalable isoporous block copolymer (BCP) membranes as carriers with an oriented and productive immobilization employing material binding peptides (MBP). Densely packed uniform enzyme-matched nanochannels of well-designed BCP membranes endow the desired nanoconfined environments towards a productive immobilized phytase. Tuning nanochannel properties can further regulate the complex reaction process and fortify the catalytic performance. The synergistic design of enzyme-matched carriers and efficient enzyme immobilization empowers an excellent catalytic performance with >1 month operational stability, superior productivity, and a high space-time yield (1.05 × 105 g L-1 d-1) via a single-pass continuous-flow process. The obtained performance makes the designed nano- and isoporous block copolymer membrane reactor highly attractive for industrial applications.

Tailored Branched Polymer-Protein Bioconjugates for Tunable Sieving Performance

Protein-polymer conjugates combine the unique properties of both proteins and synthetic polymers, making them important materials for biomedical applications. In this work, we synthesized and characterized protein-branched polymer bioconjugates that were precisely designed to retain protein functionality while preventing unwanted interactions. Using chymotrypsin as a model protein, we employed a controlled radical branching polymerization (CRBP) technique utilizing a water-soluble inibramer, sodium 2-bromoacrylate. The green-light-induced atom transfer radical polymerization (ATRP) enabled the grafting of branched polymers directly from the protein surface in the open air. The resulting bioconjugates exhibited a predetermined molecular weight, well-defined architecture, and high branching density. Conformational analysis by SEC-MALS validated the controlled grafting of branched polymers. Furthermore, enzymatic assays revealed that densely grafted polymers prevented protein inhibitor penetration, and the resulting conjugates retained up to 90% of their enzymatic activity. This study demonstrates a promising strategy for designing protein-polymer bioconjugates with tunable sieving behavior, opening avenues for applications in drug delivery and biotechnology.

Actuation for flexible and stretchable microdevices

Flexible and stretchable microdevices incorporate highly deformable structures, facilitating precise functionality at the micro- and millimetre scale. Flexible microdevices have showcased extensive utility in the fields of biomedicine, microfluidics, and soft robotics. Actuation plays a critical role in transforming energy between different forms, ensuring the effective operation of devices. However, when it comes to actuating flexible microdevices at the small millimetre or even microscale, translating actuation mechanisms from conventional rigid large-scale devices is not straightforward. The recent development of actuation mechanisms leverages the benefits of device flexibility, particularly in transforming conventional actuation concepts into more efficient approaches for flexible devices. Despite many reviews on soft robotics, flexible electronics, and flexible microfluidics, a specific and systematic review of the actuation mechanisms for flexible and stretchable microdevices is still lacking. Therefore, the present review aims to address this gap by providing a comprehensive overview of state-of-the-art actuation mechanisms for flexible and stretchable microdevices. We elaborate on the different actuation mechanisms based on fluid pressure, electric, magnetic, mechanical, and chemical sources, thoroughly examining and comparing the structure designs, characteristics, performance, advantages, and drawbacks of these diverse actuation mechanisms. Furthermore, the review explores the pivotal role of materials and fabrication techniques in the development of flexible and stretchable microdevices. Finally, we summarise the applications of these devices in biomedicine and soft robotics and provide perspectives on current and future research.

Ag-In-Zn-S alloyed nanocrystals as photocatalysts of controlled light-mediated radical polymerization

We report on the first case of the use of nonstoichiometric ternary (Ag-In-Zn-S) semiconductor nanocrystals as photoinitiators and photocatalysts of methyl methacrylate (MMA) polymerization. Two types of nanocrystals were tested, differing in their composition and characterized by red (λmax = 731 nm) and green (λmax = 528 nm) photoluminescence, respectively. Exploiting their reducing properties and capability of free radical generation we demonstrate that under ultraviolet (UV) radiation they effectively photoinitiate radical polymerization of MMA whereas under visible light (blue or green) they act as photocatalysts of living radical polymerization.

Development of High-Performance Polyindole/Silicon Carbide Nanocomposites for Optoelectrical and Sensing Applications

In this study, silicon carbide (SiC)-reinforced polyindole (PIn) nanocomposites were prepared by a simple in situ polymerization method. The successful reinforcement of the nanofiller within the host matrix was characterized using different analytical techniques. The chemical bonding of SiC in the polymer was identified by the characteristic peak around 800 cm1 using Fourier transform infrared spectroscopy (FT-IR). The increment in intensity of the absorption and enhanced crystallinity of the samples upon the addition of nanofillers were analyzed using UV-vis spectroscopy and X-ray diffraction (XRD). The prepared specimens showed reduced optical bandgap energy (3.188 eV) and Urbach energy (2.315 meV) with an improved refractive index (2.348). The effect of nanoparticles on the surface morphology of the nanocomposites was studied using scanning electron microscopy (SEM), and a uniform dispersion of fillers in the matrix was found for PInSiC7. A high-resolution transmission electron microscopy (HR-TEM) revealed the shape and average particle size of the sample. X-ray electron spectroscopy (XPS) measurements confirmed the formation of the nanocomposite by exhibiting the presence of all elements in the corresponding spectra. The thermal stability and glass transition temperature of the nanocomposites were significantly improved with the addition of SiC. The temperature-dependent AC conductivity, dielectric parameters, complex impedance, and electrical modulus were also evaluated using an impedance analyzer. The increased electrical characteristics of the PInSiC7 sample can be attributed to the uniform spread and strong synergetic interaction of SiC with PIn. The results thus showcased the potential of the samples for use in optical and energy storage applications. This study was also extended to understand the ammonia sensing properties, which make it possible to design and develop gas sensors using the PInSiC nanocomposites.

Chemically Recyclable, High Molar Mass Polyoxazolidinones via Ring-Opening Metathesis Polymerization

The development of robust methods for the synthesis of chemically recyclable polymers with tunable properties is necessary for the design of next-generation materials. Polyoxazolidinones (POxa), polymers with five-membered urethanes in their backbones, are an attractive target because they are strongly polar and have high thermal stability, but existing step-growth syntheses limit molar masses and methods to chemically recycle POxa to monomer are rare. Herein, we report the synthesis of high molar mass POxa via ring-opening metathesis polymerization of oxazolidinone-fused cyclooctenes. These novel polymers show <5% mass loss up to 382-411 °C and have tunable glass transition temperatures (14-48 °C) controlled by the side chain structure. We demonstrate facile chemical recycling to monomer and repolymerization despite moderately high monomer ring-strain energies, which we hypothesize are facilitated by the conformational restriction introduced by the fused oxazolidinone ring. This method represents the first chain growth synthesis of POxa and provides a versatile platform for the study and application of this emerging subclass of polyurethanes.

Engineering a polyvinyl butyral hydrogel as a thermochromic interlayer for energy-saving windows

Achieving mastery over light using thermochromic materials is crucial for energy-saving glazing. However, challenges such as high production costs, limited durability, and recyclability issues have hindered their widespread application in buildings. Herein, we develop a glass interlayer made of a polyvinyl butyral-based hydrogel swollen with LiCl solution. In addition to a fast, isochoric, and reversible transparency-to-opacity transition occurring as ambient temperatures exceed thermally comfortable levels, this hydrogel uniquely encompasses multiple features such as frost resistance, recyclability, scalability, and toughness. The combination of these features is achieved through a delicate balance of polyvinyl butyral's amphiphilicity and the suppression of network-forming phase separation. This design endows a nanostructured polyvinyl butyral-LiCl composite gel with swollen molecular segments linked by dispersed cross-linking sites in the form of hydrophobic nano-nodules. Upon laminating this hydrogel (a thickness of 0.3 mm), the resultant glazing product demonstrates approximately 90% luminous transmittance even at sub-zero temperatures, along with a significant modulation of solar and infrared radiation at 80.8% and 68.5%, respectively. Through simulations, we determined that windows equipped with the hydrogel could reduce energy consumption by 36% compared to conventional glass windows in warm seasons. The widespread adoption of polyvinyl butyral in construction underscores the promise of this hydrogel as a thermochromic interlayer for glazing.

Recent advances in shape memory polymeric nanocomposites for biomedical applications and beyond

Shape memory polymers (SMPs), which initiate shape transformation in response to environmental stimuli, have attracted significant attention in both academic research and technological innovation. The combination of functional nanomaterials and SMPs has led to the emergence of a variety of shape memory polymeric nanocomposites (SMPNs) with multifunctional properties. This has injected new vitality and vigor into fields such as tissue engineering, biomedicine, optical sensing, aerospace and mechanical engineering. In this review article, we present a brief introduction to the fundamentals of SMPs and SMPNs, followed by a discussion of the recent advances in their multifunctional applications in biomedical manufacturing, drug delivery devices, mechanical sensing, micro-engines, etc. The opportunities and challenges in the future development of SMPs are also discussed.

A Sacrificial Linker in Biodegradable Polyesters for Accelerated Photoinduced Degradation, Monitored by Continuous Atline SEC Analysis

Polymeric materials that undergo photoinduced degradation have wide application in fields such as controlled release. Most methods for photoinduced degradation rely on the UV or near-UV region of the electromagnetic spectrum; however, use of the deeply penetrating and benign wavelengths of visible light offers a multitude of advantages. Here we report a lactone monomer for ring-opening copolymerizations to introduce a sacrificial linker into a polymer backbone which can be cleaved by reactive oxygen species which are produced by a photocatalyst under visible light irradiation. We find that copolymers of this material readily degrade under visible light. We followed polymer degradation using a continuous flow size exclusion chromatography system, the components of which are described herein.

Application of the Born Model to Describe Salt Partitioning in Hydrated Polymers

The classic Born model can be used to predict salt partitioning properties observed in hydrated polymers, but there are often significant quantitative discrepancies between these predictions and the experimental data. Here, we use an updated version of the Born model, reformulated to account for the local environment and mesh size of a hydrated polymer, to describe previously published NaCl, KCl, and LiCl partitioning properties of model cross-linked poly(ethylene glycol) diacrylate polymers. This reformulated Born model describes the influence of polymer structure (i.e., network mesh size and its relationship with water content) and external salt concentration on salt partitioning in the polymers with a significant improvement relative to the classic Born model. The updated model most effectively describes NaCl partitioning properties and provides an additional fundamental understanding of salt partitioning processes, for NaCl, KCl, and LiCl, in hydrated polymers that are of interest for a variety of environmental and biological applications.

Orientation of reduced graphene oxide in composite coatings

Composite coatings containing reduced graphene oxide (rGO) and 3-(aminopropyl)triethoxysilane functionalised rGO (APTES-rGO) were prepared by sol-gel technology and deposited on Al 2024 T-3. Covalent functionalisation of GO by APTES occurred by formation of amide bonds, accompanied by GO reduction. The thin sheets were retained. The hydrophilicity of the coating increased when APTES-rGO was added. The opposite was observed when GO was added. A key finding is that the rGO flakes agglomerate and lie in a random orientation in the coating, whereas the APTES-rGO flakes are more evenly distributed in the matrix and appear to lie along the plane of the substrate.

A new era of targeting cystic fibrosis with non-viral delivery of genomic medicines

Cystic fibrosis (CF) is a complex genetic respiratory disorder that necessitates innovative gene delivery strategies to address the mutations in the gene. This review delves into the promises and challenges of non-viral gene delivery for CF therapy and explores strategies to overcome these hurdles. Several emerging technologies and nucleic acid cargos for CF gene therapy are discussed. Novel formulation approaches including lipid and polymeric nanoparticles promise enhanced delivery through the CF mucus barrier, augmenting the potential of non-viral strategies. Additionally, safety considerations and regulatory perspectives play a crucial role in navigating the path toward clinical translation of gene therapy.

Exploring a Solvent Dependent Strategy to Control Self-Assembling Behavior and Cellular Interaction in Laminin-Mimetic Short Peptide based Supramolecular Hydrogels

Self-assembled hydrogels, fabricated through diverse non-covalent interactions, have been extensively studied in regenerative medicines. Inspired from bioactive functional motifs of ECM protein, short peptide sequences have shown remarkable abilities to replicate the intrinsic features of the natural extracellular milieu. In this direction, we have fabricated two short hydrophobic bioactive sequences derived from the laminin protein i. e., IKVAV and YIGSR. Based on the substantial hydrophobicity of these peptides, we selected a co-solvent approach as a suitable gelation technique that included different concentrations of DMSO as an organic phase along with an aqueous solution containing 0.1 % TFA. These hydrophobic laminin-based bioactive peptides with limited solubility in aqueous physiological environment showed significantly enhanced solubility with higher DMSO content in water. The enhanced solubility resulted in extensive intermolecular interactions that led to the formation of hydrogels with a higher-order entangled network along with improved mechanical properties. Interestingly, by simply modulating DMSO content, highly tunable gels were accessed in the same gelator domain that displayed differential physicochemical properties. Further, the cellular studies substantiated the potential of these laminin-derived hydrogels in enhancing cell-matrix interactions, thereby reinforcing their applications in tissue engineering.

Natural Polymers - Based Hydrogel Dressings for Wound Healing

SIGNIFICANCE

Acute wounds such as severe burns and chronic wounds like diabetic ulcers present a significant threat to human health. Wound dressings made from natural polymers offer inherent properties that effectively enhance wound healing outcomes and reduce healing time.

RECENT ADVANCES

Numerous innovative hydrogels are being developed and translated to the clinic to successfully treat various wound types. This underscores the substantial potential of hydrogels in the future wound care market. Economically, annual sales of wound care products are projected to reach $15-22 billion by 2024.

CRITICAL ISSUES

While chitosan-, cellulose-, and collagen-based hydrogel dressings are currently commercially available, scaling up and manufacturing hydrogels for commercial products remains a challenging process. Additionally, ensuring the sterility and stability of the chemical or biological components comprising the hydrogel are critical considerations.

FUTURE DIRECTIONS

In light of the persistent increase in wound fatalities and the resulting economic and social impacts, as well as the importance of educating the public about dietary health and disease, there should be increased investment in new wound care dressings, particularly hydrogels derived from natural products. With numerous researchers dedicated to advancing preclinical hydrogels, the future holds promise for more innovative and more personalized hydrogel wound dressings.

Morphological Transformation and Surface Engineering of Glycovesicles Driven by Bioinspired Hydrogen Bonds of Nucleobases

Glycopolymer-based supramolecular glycoassemblies with signal-driven cascade morphological deformation and accessible surface engineering toward bioinspired functional glycomaterials have attracted much attention due to their diverse applications in fundamental and practical scenarios. Herein, we achieved the cascade morphological transformation and surface engineering of a nucleobase-containing polymeric glycovesicle through exploiting the bioinspired complementary multiple hydrogen bonds of complementary nucleobases. First, the synthesized thymine-containing glycopolymers (PGal30-b-PTAm249) are capable of self-assembling into well-defined glycovesicles. Several kinds of amphiphilic adenine-containing block copolymers with neutral, positive, and negative charges were synthesized to engineer the glycovesicles through the multiple hydrogen bonds between adenine and thymine. A cascade of morphological transformations from vesicles to ruptured vesicles with tails, to worm-like micelles, and finally to spherical micelles were observed via continuously adding the adenine-containing polymer into the thymine-containing glycovesicles. Furthermore, the surface charge properties of these glyconano-objects can be facilely regulated through incorporating various adenine-containing polymers. This work demonstrates the potential application of a unique bioinspired approach to precisely engineer the morphology and surface properties of glycovesicles for boosting their biological applications.

Tethered Helical Ladder-Type Aromatic Lactams

Tethered nonplanar aromatics (TNAs) make up an important class of nonplanar aromatic compounds showing unique features. However, the knowledge on the synthesis, structures, and properties of TNAs remains insufficient. In this work, a new type of TNAs, the tethered aromatic lactams, is synthesized via Pd-catalyzed consecutive intramolecular direct arylations. These molecules possess a helical ladder-type conjugated system of up to 13 fused rings. The overall yields ranged from 3.4 to 4.3%. The largest of the tethered aromatic lactams, 6L-Bu-C14, demonstrates a guest-adaptive hosting capability of TNAs for the first time. When binding fullerene guests, the cavity of 6L-Bu-C14 became more circular to better accommodate spherical fullerene molecules. The host-guest interaction is thoroughly studied by X-ray crystallography, theoretical calculations, fluorescence titration, and nuclear magnetic resonance (NMR) titration experiments. 6L-Bu-C14 shows stronger binding with C70 than with C60 due to the better convex-concave π-π interaction. P and M enantiomers of all tethered aromatic lactams show distinct and persistent chiroptical properties and demonstrate the potential of chiral TNAs as circularly polarized luminescence (CPL) emitters.

Defining Reactivity-Deconstructability Relationships for Copolymerizations Involving Cleavable Comonomer Additives

The incorporation of cleavable comonomers as additives into polymers can imbue traditional polymers with controlled deconstructability and expanded end-of-life options. The efficiency with which cleavable comonomer additives (CCAs) can enable deconstruction is sensitive to their local distribution within a copolymer backbone, which is dictated by their copolymerization behavior. While qualitative heuristics exist that describe deconstructability, comprehensive quantitative connections between CCA loadings, reactivity ratios, polymerization mechanisms, and deconstruction reactions on the deconstruction efficiency of copolymers containing CCAs have not been established. Here, we broadly define these relationships using stochastic simulations characterizing various polymerization mechanisms (e.g., coltrolled/living, free-radical, and reversible ring-opening polymerizations), reactivity ratio pairs (spanning 2 orders of magnitude between 0.01 and 100), CCA loadings (2.5% to 20%), and deconstruction reactions (e.g., comonomer sequence-dependent deconstruction behavior). We show general agreement between simulated and experimentally observed deconstruction fragment sizes from the literature, demonstrating the predictive power of the methods used herein. These results will guide the development of more efficient CCAs and inform the formulation of deconstructable materials.

Boundary Frustration in Double-Gyroid Thin Films

Self-consistent field theory for thin films of AB diblock polymers in the double-gyroid phase reveals that in the absence of preferential wetting of monomer species at the film boundaries, films with the (211) plane oriented parallel to the boundaries are more stable than other orientations, consistent with experimental results. This preferred orientation is explained in the context of boundary frustration. Specifically, the angle of intersection between the A/B interface and the film boundary, the wetting angle, is thermodynamically restricted to a narrow range of values. Most termination planes in the double gyroid cannot accommodate this narrow range of wetting angles without significant local distortion relative to the bulk morphology; the (211)-oriented termination plane with the "double-wave" pattern produces relatively minimal distortion, making it the least frustrated boundary. The principle of boundary frustration provides a framework to understand the relative stability of termination planes for complex ordered block polymer phases confined between flat, nonpreferential boundaries.

Fine-Tuning Electron-Donor Capability in the Basic Anion of Poly(ionic liquid) Frameworks for Revolutionizing Catalytic Synthesis of Ethyl Methyl Carbonate with Both Ultrahigh Catalytic Activity and Selectivity

Ethyl methyl carbonate (EMC) is a crucial solvent extensively utilized in lithium-ion battery electrolytes; the transesterification of dimethyl carbonate (DMC) with ethanol is a pivotal reaction for EMC production. However, this reaction faces challenges due to the trade-off between catalytic activity and selectivity from the basic catalysts. In this issue, we report an innovative strategy through fine-tuning the electron-donor capability of the basic phenolate anion ([PhO]) in a novel poly(ionic liquid) (PIL) framework, as synthesized via an alkylation reaction between 1,3,5-tris(bromomethyl)benzene, biphenyldiimidazole, and N,N'-carbonyldiimidazole (CDI) to trigger targeted basicity that can directionally catalyze the transesterification of DMC with ethanol, so as to achieve both ultrahigh catalytic activity and selectivity toward EMC. By varying the substituent groups with electron-withdrawing and electron-donating effects on the phenolate anion, the PILs show expected changes in the catalytic performance, following well with the trend of charge density on these substituted phenolate anions. The optimized catalyst [CPIL-CDI][MeOPhO], induced by p-methoxyphenolate anions, allows an extraordinary EMC yield of 72.19% and an EMC selectivity of 91.48% under mild conditions without any process intensifications, suppressing all of the reported catalysts reported to date. Outcomes and approaches shown in this work have the potential to expedite the systematic design of cations and anions within PILs for industrial-scale EMC production through environmentally friendly transesterification processes.

Spiropyran-Based Photoisomerizable α-Amino Acid for Membrane-Active Peptide Modification

Photoisomerizable peptides are promising drug candidates in photopharmacology. While azobenzene- and diarylethene-containing photoisomerizable peptides have already demonstrated their potential in this regard, reports on the use of spiropyrans to photoregulate bioactive peptides are still scarce. This work focuses on the design and synthesis of a spiropyran-derived amino acid, (S)-2-amino-3-(6'-methoxy-1',3',3'-trimethylspiro-[2H-1-benzopyran-2,2'-indolin-6-yl])propanoic acid, which is suitable for the preparation of photoisomerizable peptides. The utility of this amino acid is demonstrated by incorporating it into the backbone of BP100, a known membrane-active peptide, and by examining the photoregulation of the membrane perturbation by the spiropyran-containing peptides. The toxicity of the peptides (against the plant cell line BY-2), their bacteriotoxicity (E. coli), and actin-auxin oscillator modulation ability were shown to be significantly dependent on the photoisomeric state of the spiropyran unit.

Enhancing Adhesion Properties of Commodity Polymers through Thiol-Catechol Connectivities: A Case Study on Polymerizing Polystyrene-Telechelics via Thiol-Quinone Michael-Polyaddition

Segmented block copolymers with adhesive functionality bridges in between are synthesized through the combination of controlled radical polymerization (CRP) and thiol-quinone Michael-polyaddition. CRP provides a set of α,ω-dithiol polystyrenes (PS), which react as telechelics with a low molecular weight bisquinone, resulting in thiol-catechol connectivities (TCCs). By introducing as little as 3 mol % of TCC functionalities, the bonding of the polymer on dry and wet aluminum surfaces is significantly improved while keeping the integrity of the PS segments undisturbed to constitute favorable bulk properties. This improvement is evidenced by reaching up to 3.8 MPa adhesive strength, representing a 600% increase compared to nonfunctional PS.

Electrospun polylactic acid nanofibers membrane with copper ion-loaded clay nanotubes for fresh-keeping packaging

The plastics derived from fossil fuels for food packaging results in serious environmental problems. Developing environment-friendly materials for food packaging is urgent and essential. In this study, polylactic acid (PLA) composite nanofibers membranes were prepared with good biocompatibility and antibacterial property. Cu2+ loaded in the natural halloysite nanotubes (HNTs) was used for the antibacterial agent. Cu2+ was loaded in the HNTs and was confirmed by the X-ray photoelectron spectroscopy (XPS). PLA nanofibers with different HNTs-Cu content were continuous nanofibers with the nanoscale range. HNTs-Cu entered into the nanofiber successfully. Thermal analysis results showed composite nanofibers had good thermal stability. Composite nanofiber membranes had the good hydrophobic property. HNTs-Cu improved the mechanical property of composite nanofibers than pure PLA nanofibers. Tensile strength and elasticity modulus of composite nanofibers with 4 % HNTs-Cu content were the most outstanding. L929 cells were cultured on the nanofiber membranes for biocompatibility evaluation. Cell viability of nanofiber membranes was above the 90 %. Cell live/dead staining results showed L929 cells was seldom dead on the nanofiber membranes. PLA/HNTs-Cu nanofiber membranes exhibited excellent antibacterial effects on S. aureus and E. coli. The inhibitory rates against S. aureus and E. coli were 98.31 % and 97.80 % respectively. The fresh-keeping effects of nanofiber membranes were evaluated by the strawberry preservation. Strawberries covered by nanofiber membranes exhibited better appearance, lower weight loss and higher firmness than control, PLA and PLA/HNTs groups. It promised that PLA/HNTs-Cu composite nanofiber membranes have the significant potential application for active food packaging.

Design of sec-Benzyl Vinyl Ethers toward the Synthesis of Alternating Copolymers Composed of Vinyl Alcohol and Vinyl Ether Units

In this work, we designed benzyl vinyl ethers carrying alkyl substituents at the benzyl position (i.e., sec-BnVEs) as bulky, reactive, and transformable monomers to realize the alternating cationic copolymerization with an alkyl vinyl ether (VE). In particular, the isopropyl substitution caused not only the bulkiness to suppress the successive propagation but also an enhancement of the vinyl group reactivity to promote crossover propagation with a less bulky VE comonomer. The isopropyl-substituted BnVE (iPr-BnVE) underwent living cationic alternating copolymerization with n-butyl VE (nBVE), and the alternating propagation was strongly suggested by the reactivity ratios. The subsequent deprotection of the sec-benzyl pendant afforded the vinyl alcohol (VA)-nBVE alternating copolymer, and the corresponding statistical copolymer was also synthesized by using the nonsubstituted monomer (BnVE) instead of iPr-BnVE. The alternating copolymer exhibited a higher glass transition temperature, which likely stems from the uniform and efficient hydrogen-bonding formation due to the periodic sequence.

Comparative Study on the Lubrication Mechanism and Performance of Two Representative Ionic and Nonionic Self-Adhesive Polymer Coatings

Surface modification of lubricating coatings on biomedical devices is a pivotal strategy to improve the overall performance and clinical efficacy, significantly reducing friction between devices and human tissues and mitigating tissue damage during intervention and long-term implantation. Recently, various hydrophilic polymeric materials have been used for achieving surface functionalization, endowing the biomedical device with excellent superlubrication performance. N-Vinylpyrrolidone (NVP) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are two typical representatives of nonionic and zwitterionic materials. However, there is still a research gap in a comparative study of the lubrication mechanisms and properties between them. In this study, a bioinspired and dopamine-assisted codeposition technique was used to fabricate biomimetic hydrophilic coatings, including P(DMA-NVP) and P(DMA-MPC), on polyurethane. To achieve a thorough comparative analysis of the self-adhesive coating performance, 3 M ratios of the copolymers were synthesized and comprehensive material evaluations were conducted. Additionally, surface morphology, hydrophilicity, and lubrication at both the microscale and macroscale were performed. It was found that both hydrophilic coatings exhibited good stability. The P(DMA-MPC) coating, due to the ability to attract and bind a large number of water molecules, demonstrated superior lubrication effects compared to the P(DMA-NVP) coating. The study provides an in-depth understanding of the lubrication behavior of the self-adhesive coatings to enhance the functionality and application in biomedical engineering.

"Flexible-strong" polylactic acid porous membrane via tailored polymerization degree of lactic acid side-chains grafting for passive daytime radiative cooler

Aerogel possesses the advantages of high specific surface area, low density, and high porosity, which have shown great application in thermal regulation due to its efficient light scattering capability. However, traditional polymer-based aerogels have poor mechanical properties and lack ductility in outdoor applications, the cooling efficiency of the material is easily affected by damage during transportation, installation, and environmental factors. In this work, combining the porous nature of aerogels and the high ductility of membranes, a polylactic acid-based porous membrane cooler was developed by combining a regular honeycomb surface porous structure design and physical/chemical modification to enhance flexibility, using a simple non-solvent induced phase separation method. This porous membrane exhibits both super-flexibility (116 % elongation at break) and porous characteristics. It achieves a sub-ambient temperature decrease of 4-6 °C under direct sunlight. The optimized porous membrane demonstrates high solar reflectance (94 % of peak reflectivity, 90 % of average reflectivity) and strong infrared emissivity (96 % of peak emissivity, 91 % of average emissivity), it also maintains a solar peak reflectivity of 91 % under 100 % tensile strain and 1000 bending cycles, the cooler still maintains a cooling effect of 2-5 °C below ambient temperature. This work paves the way for developing mechanical flexible and strong radiative coolers for thermal regulation.

Recent advancements in polyurethane-based membranes for gas separation

Gas separation membranes are critical in a variety of environmental research and industrial applications. These membranes are designed to selectively allow some gases to flow while blocking others, allowing for the separation and purification of gases for a variety of applications. Therefore, the demand for fast and energy-efficient gas separation techniques is of central interest for many chemical and energy production diligences due to the intensified levels of greenhouse and industrial gases. This encourages the researchers to innovate techniques for capturing and separating these gases, including membrane separation techniques. Polymeric membranes play a significant role in gas separations by capturing gases from the fuel combustion process, purifying chemical raw material used for plastic production, and isolating pure and noncombustible gases. Polyurethane-based membrane technology offers an excellent knack for gas separation applications and has also been considered more energy-efficient than conventional phase change separation methodologies. This review article reveals a thorough delineation of the current developments and efforts made for PU membranes. It further explains its uses for the separation of valuable gases such as carbon dioxide (CO2), hydrogen (H2), nitrogen (N2), methane (CH4), or a mixture of gases from a variety of gas spillages. Polyurethane (PU) is an excellent choice of material and a leading candidate for producing gas-separating membranes because of its outstanding chemical chemistry, good mechanical abilities, higher permeability, and variable microstructure. The presence of PU improves several characteristics of gas-separating membranes. Selectivity and separation efficiency of PU-centered membranes are enhanced through modifications such as blending with other polymers, use of nanoparticles (silica, metal oxides, alumina, zeolite), and interpenetrating polymer networks (IPNs) formation. This manuscript critically analyzes the various gas transport methods and selection criteria for the fabrication of PU membranes. It also covers the challenges facing the development of PU-membrane-based separation procedures.

Research trends of bio-application of major components in lignocellulosic biomass (cellulose, hemicellulose and lignin) in orthopedics fields based on the bibliometric analysis: A review

Cellulose, hemicellulose, and lignin are the major bio-components in lignocellulosic biomass (BC-LB), which possess excellent biomechanical properties and biocompatibility to satisfy the demands of orthopedic applications. To understand the basis and trends in the development of major bio-components in BC-LB in orthopedics, the bibliometric technology was applied to get unique insights based on the published papers (741) in the Web of Science (WOS) database from January 1st, 2001, to February 14th, 2023. The analysis includes the annual distributions of publications, keywords co-linearity, research hotspots exploration, author collaboration networks, published journals, and clustering of co-cited literature. The results reveal a steady growth in publications focusing on the application of BC-LB in orthopedics, with China and the United States leading in research output. The "International Journal of Biological Macromolecules" was identified as the most cited journal for BC-LB research in orthopedics. The research hotspots encompassed bone tissue engineering, cartilage tissue engineering, and drug delivery systems, indicating the fundamental research and potential development in these areas. This study also highlights the challenges associated with the clinical application of BC-LB in orthopedics and provides valuable insights for future advancements in the field.

Chromatographic Separation: A Versatile Strategy to Prepare Discrete and Well-Defined Polymer Libraries

ConspectusThe preparation of discrete and well-defined polymers is an emerging strategy for emulating the remarkable precision achieved by macromolecular synthesis in nature. Although modern controlled polymerization techniques have unlocked access to a cornucopia of materials spanning a broad range of monomers, molecular weights, and architectures, the word "controlled" is not to be confused with "perfect". Indeed, even the highest-fidelity polymerization techniques─yielding molar mass dispersities in the vicinity of Đ = 1.05─unavoidably create a considerable degree of structural and/or compositional dispersity due to the statistical nature of chain growth. Such dispersity impacts many of the properties that researchers seek to control in the design of soft materials.The development of strategies to minimize or entirely eliminate dispersity and access molecularly precise polymers therefore remains a key contemporary challenge. While significant advances have been made in the realm of iterative synthetic methods that construct oligomers with an exact molecular weight, head-to-tail connectivity, and even stereochemistry via small-molecule organic chemistry, as the word "iterative" suggests, these techniques involve manually propagating monomers one reaction at a time, often with intervening protection and deprotection steps. As a result, these strategies are time-consuming, difficult to scale, and remain limited to lower molecular weights. The focus of this Account is on an alternative strategy that is more accessible to the general scientific community because of its simplicity, versatility, and affordability: chromatography. Researchers unfamiliar with the intricacies of synthesis may recall being exposed to chromatography in an undergraduate chemistry lab. This operationally simple, yet remarkably powerful, technique is most commonly encountered in the purification of small molecules through their selective (differential) adsorption to a column packed with a low-cost stationary phase, usually silica. Because the requisite equipment is readily available and the actual separation takes little time (on the order of 1 h), chromatography is used extensively in small-molecule chemistry throughout industry and academia alike. It is, therefore, perhaps surprising that similar types of chromatography are not more widely leveraged in the field of polymer science as well.Here, we discuss recent advances in using chromatography to control the structure and properties of polymeric materials. Emphasis is placed on the utility of an adsorption-based mechanism that separates polymers based on polarity and composition at tractable (gram) scales for materials science, in contrast to size exclusion, which is extremely common but typically analyzes very small quantities of a sample (∼1 mg) and is limited to separating by molar mass. Key concepts that are highlighted include (1) the separation of low-molecular-weight homopolymers into discrete oligomers (Đ = 1.0) with precise chain lengths and (2) the efficient fractionation of block copolymers into high-quality and widely varied libraries for accelerating materials discovery. In summary, the authors hope to convey the exciting possibilities in polymer science afforded by chromatography as a scalable, versatile, and even automated technique that unlocks new avenues of exploration into well-defined materials for a diverse assortment of researchers with different training and expertise.