Exploring the advantages of oxygen-tolerant thiol-ene polymerization over conventional acrylate free radical photopolymerization processes for pressure-sensitive adhesives

Research Progress of Polyacrylate Binders for Silicon-Based Anodes in Lithium-Ion Batteries

Silicon (Si) has emerged as a preeminent candidate for next-generation lithium-ion batteries (LIBs) anodes, primarily attributed to its exceptionally high specific capacity. Nevertheless, the substantial volumetric expansion accompanying lithium alloying reactions has long posed a critical challenge to the commercial viability of silicon-based anodes. Binders as connectors between the active Si particles, conductive agents, and current collectors, playing a crucial role in stabilizing the structure of silicon anodes in LIBs. Polyacrylic acid (PAA) water-based binders contain abundant carboxyl groups (─COOH) that can enhance adhesive strength. However, simple linear PAA does not adequately accommodate the significant volume expansion of silicon anodes. To address this issue, various structural optimization strategies have been applied to modify PAA binders. In this context, a comprehensive review is conducted on the recently developed PAA-based binders, which cover linear, branched, and 3D network configurations. A meticulous comparison is carried out regarding their initial coulombic efficiency, areal capacity, and material costs. Moreover, in-depth insights are offered to elucidate the mechanisms by which these structural modifications augment the properties of the binders and the performance of the cells. Ultimately, the prospective directions for the evolution of PAA-based binders designed for Si-based anodes in high-energy-density LIBs are deliberated.

Thiol-Ene Photopolymerization and 3D Printing of Non-Modified Castor Oil Containing Bio-Based Cellulosic Fillers

The photopolymerization process in 3D printing is considered greener once it involves a fast reaction and low energy consumption. Various reactions for photopolymerization can be used nowadays, but a special one is the thiol-ene "click" reaction that occurs in equimolar concentrations of thiol and alkene groups. In this sense, solvent-free photopolymerizable formulations were prepared to contain non-modified castor oil, Trimethylolpropane tris(3-mercapto propionate), and cellulosic fillers from hemp, tagua, and walnut. All formulations presented conversions higher than 70% and fast polymerization rates. Moreover, the filled formulations presented excellent curing depths in fewer seconds of light exposition, an important factor for their applicability in 3D printing. Furthermore, the hemp filler formulation presented the highest crosslinking density as determined by the DMTA, and was selected for printing two complex structures (pyramid and honeycomb shape). The rheology analysis showed that the formulations had adequate viscosities for the printer. Lastly, all polymers presented at least 97% bio-based contents, with gel contents superior to 96%.

Chemical- and photo-activation of protein-protein thiol-ene coupling for protein profiling

The thiol-ene reaction between an alkene and a thiol can be exploited for selective labelling of cysteine residues in protein profiling applications. Here, we explore thiol-ene activation in systems from chemical models to complex cellular milieus, using UV, visible wavelength and redox initiators. Initial studies in chemical models required an oxygen-free environment for efficient coupling and showed very poor activation when using a redox initiator. When thiol-ene activation was performed in protein and cell lysate models, all three initiation methods were successful. Faster thiol-ene reaction was observed as the cysteine and alkene were brought into proximity by a binding event prior to activation, leading to quicker adduct formation in the protein model system than the chemical models. Furthermore, in the protein-protein coupling, none of the activators required an oxygen-free environment. Taken together, these observations demonstrate the broad potential for thiol-ene coupling to be used in protein profiling.

Optical Adhesives and Screen Sealants for Foldable Displays: Analysis, Progress and Trends

The realm of flexible display devices, particularly centered around folding screen smartphones, is undergoing rapid advancements. As integral components, optical adhesives and screen sealants for these devices play pivotal roles in determining their overall performance. This paper provides a comprehensive overview of the evolution of display technology and display screens, delving into the critical function of optical adhesives within this framework. Notably, light-curing adhesives stand out for their paramount importance in display screen manufacturing, attributed to their swift curing capabilities. We synthesize the key research achievements and concomitant limitations pertaining to the characteristics of diverse flexible optical adhesives compositions over recent years. Furthermore, we delve into the influence of chemical modification techniques applied to various adhesive systems and the integration of physical doping fillers on enhancing the performance of screen sealants.

Optical Fiber-Assisted Printing: A Platform Technology for Straightforward Photopolymer Resins Patterning and Freeform 3D Printing

Light-based 3D printing techniques represent powerful tools, enabling the precise fabrication of intricate objects with high resolution and control. An innovative addition to this set of printing techniques is Optical Fiber-Assisted Printing (OFAP) introduced in this article. OFAP is a platform utilizing an LED-coupled optical fiber (LOF) that selectively crosslinks photopolymer resins. It allows change of parameters like light intensity and LOF velocity during fabrication, facilitating the creation of structures with progressive features and multi-material constructs layer-by-layer. An optimized formulation based on allyl-modified gelatin (gelAGE) with food dyes as photoabsorbers is introduced. Additionally, a novel gelatin-based biomaterial, alkyne-modified gelatin (gelGPE), featuring alkyne moieties, demonstrates near-visible light absorption thus fitting OFAP needs, paving the way for multifunctional hydrogels through thiol-yne click chemistry. Besides 2D patterning, OFAP is transferred to embedded 3D printing within a resin bath demonstrating the proof-of-concept as a novel printing technology with potential applications in tissue engineering and biomimetic scaffold fabrication, offering rapid and precise freeform printing capabilities.

Light-Mediated Polymerization Catalyzed by Carbon Nanomaterials

Carbon nanomaterials, specifically carbon dots and carbon nitrides, play a crucial role as heterogeneous photoinitiators in both radical and cationic polymerization processes. These recently introduced materials offer promising solutions to the limitations of current homogeneous systems, presenting a novel approach to photopolymerization. This review highlights the preparation and photocatalytic performance of these nanomaterials, emphasizing their application in various polymerization techniques, including photoinduced i) free radical, ii) RAFT, iii) ATRP, and iv) cationic photopolymerization. Additionally, it discusses their potential in addressing contemporary challenges and explores prospects in this field. Moreover, carbon nitrides, in particular, exhibit exceptional oxygen tolerance, underscoring their significance in radical polymerization processes and allowing their applications such as 3D printing, surface modification of coatings, and hydrogel engineering.

Flexible Allyl-Modified Gelatin Photoclick Resin Tailored for Volumetric Bioprinting of Matrices for Soft Tissue Engineering

Volumetric bioprinting (VBP) is a light-based 3D printing platform, which recently prompted a paradigm shift for additive manufacturing (AM) techniques considering its capability to enable the fabrication of complex cell-laden geometries in tens of seconds with high spatiotemporal control and pattern accuracy. A flexible allyl-modified gelatin (gelAGE)-based photoclick resin is developed in this study to fabricate matrices with exceptionally soft polymer networks (0.2-1.0 kPa). The gelAGE-based resin formulations are designed to exploit the fast thiol-ene crosslinking in combination with a four-arm thiolated polyethylene glycol (PEG4SH) in the presence of a photoinitiator. The flexibility of the gelAGE biomaterial platform allows one to tailor its concentration spanning from 2.75% to 6% and to vary the allyl to thiol ratio without hampering the photocrosslinking efficiency. The thiol-ene crosslinking enables the production of viable cell-material constructs with a high throughput in tens of seconds. The suitability of the gelAGE-based resins is demonstrated by adipogenic differentiation of adipose-derived stromal cells (ASC) after VBP and by the printing of more fragile adipocytes as a proof-of-concept. Taken together, this study introduces a soft photoclick resin which paves the way for volumetric printing applications toward soft tissue engineering.

Direct in situ photolithography of perovskite quantum dots based on photocatalysis of lead bromide complexes

Photolithography has shown great potential in patterning solution-processed nanomaterials for integration into advanced optoelectronic devices. However, photolithography of perovskite quantum dots (PQDs) has so far been hindered by the incompatibility of perovskite with traditional optical lithography processes where lots of solvents and high-energy ultraviolet (UV) light exposure are required. Herein, we report a direct in situ photolithography technique to pattern PQDs based on the photopolymerization catalyzed by lead bromide complexes. By combining direct photolithography with in situ fabrication of PQDs, this method allows to directly photolithograph perovskite precursors, avoiding the complicated lift-off processes and the destruction of PQDs by solvents or high-energy UV light, as PQDs are produced after lithography exposure. We further demonstrate that the thiol-ene free-radical photopolymerization is catalyzed by lead bromide complexes in the perovskite precursor solution, while no external initiators or catalysts are needed. Using direct in situ photolithography, PQD patterns with high resolution up to 2450 pixels per inch (PPI), excellent fluorescence uniformity, and good stability, are successfully demonstrated. This work opens an avenue for non-destructive direct photolithography of high-efficiency light-emitting PQDs, and potentially expands their application in various integrated optoelectronic devices.

Perovskite nanomaterials may suffer degradation during conventional photolithography. Here, the authors report a non-destructive method for patterning perovskite quantum dots based on direct photopolymerization catalyzed by lead bromide complexes.