Preparation of PLA blends by polycondensation of D,L-lactic acid using supported 12-tungstophosphoric acid as a heterogeneous catalyst

Controlling Oligomer Chain Length via Ultrasonic Pretreatment in Lactic Acid Polycondensation for Enhanced Poly(lactic acid) ROP

Controlling oligomer chain length in lactic acid (LA) polycondensation is crucial for producing good properties of poly(lactic acid) (PLA). This study explores the use of ultrasonic pretreatment to reduce the water content of LA, aiming to optimize the polycondensation process and enhance the quality of PLA through ring-opening polymerization (ROP). The methodology involved varying ultrasonic treatment time and power during LA pretreatment, followed by polycondensation at the optimized temperature. The study results indicate that ultrasonic pretreatment effectively reduces the water content in LA, with optimal conditions found at 90 min and 75 W, yielding the lowest water content. The polycondensation process, conducted at a gradual temperature of 150 °C followed by 180 °C, resulted in the highest yield of 92.75% and a molecular weight of 25,126 g/mol for the oligomers. Ultrasonic pretreatment enhances water removal efficiency, reduces byproduct formation, and increases oligomer reactivity, resulting in higher-purity oligomers and improved chain length control. During the ROP stage, oligomers prepared through ultrasonic pretreatment produced PLA with a higher molecular weight and crystallinity.

Production and characterization of human hair keratin bioplastic films with novel plasticizers

Since their invention, conventional plastics have contributed in the betterment of the society in numerous ways, nevertheless their deleterious impacts on the natural ecosystems and living creatures is irrefutable. The management of plastic waste generated is a concern worldwide and therefore quest for the plastic alternates or bioplastics is imminent. Here, we explore the suitability of keratin from human hair waste as the candidate for the production of bioplastic films. Keratin extracted from hair was used to form the films or 'kertics' by solution casting and curing. Ethanediol, di-ethylene glycol and tri-ethylene glycol were used as novel plasticizers along with glycerol in the keratin film formation. The film prepared were of the thickness 190-220 µm with the area of about 4.54 ± 0.2 cm2. Water uptake by G100, ED100, DEG100 and TEG100 films was recorded to be 4.8, 6.2, 4.9 and 6.3% respectively. FESEM analysis revealed that the films with 100 µl of 1% glycerol (G100) had continuous surface morphology except few pits of 0.1 µm, also DEG100 and TEG100 films have the most uniform surface morphology with no evident pits, holes or bulges. X-ray diffractogram showed characteristic peak of keratin at 19.5° and the d-spacing value observed was 0.45 nm. The FTIR studies suggested that the films retained keratin in non degraded form, and possessed the characteristic Amide peaks. The films were also found to be biodegradable in studies involving keratinophilic fungal strain of A. oryzae. These films could found potential applications in packaging industry, disposable items manufacturing and biomaterial generation.

Sonochemical Synthesis of Magnetite/Poly(lactic acid) Nanocomposites

Nanocomposites based on poly(lactic acid) (PLA) and magnetite nanoparticles (MNP-Fe3O4) show promise for applications in biomedical treatments. One key challenge is to improve the stabilization and dispersion of MNP-Fe3O4. To address this, we synthesized MNP-Fe3O4/PLA nanocomposites using ultrasound mediation and a single iron(II) precursor, eliminating the need for surfactants or organic solvents, and conducted the process under ambient conditions. The resulting materials, containing 18 and 33 wt.% Fe3O4, exhibited unique thermal behavior characterized by two mass losses: one at a lower degradation temperature (Td) and another at a higher Td compared to pure PLA. This suggests that the interaction between PLA and MNP-Fe3O4 occurs through hydrogen bonds, enhancing the thermal stability of a portion of the polymer. Fourier Transform Infrared (FT-IR) analysis supported this finding, revealing shifts in bands related to the terminal -OH groups of the polymer and the Fe-O bonds, thereby confirming the interaction between the groups. Raman spectroscopy demonstrated that the PLA serves as a protective layer against the oxidation of MNP-Fe3O4 in the 18% MNP-Fe3O4/PLA nanocomposite when exposed to a high-power laser (90 mW). Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses confirmed that the synthetic procedure yields materials with dispersed nanoparticles within the PLA matrix without the need for additional reactants.

Synthesis and Modeling of Poly(L-lactic acid) via Polycondensation of L-Lactic Acid

We present synthetic experiments of lactic acid (LA) polycondensation to produce poly(lactic acid) (PLA) as well as kinetic modeling calculations that capture the polymer molecular weight increase with time, given the initial concentrations. Tin-octoate-catalyzed polycondensation of (D,L)- or L-lactic acid was carried out in pre-dried toluene after azeotropic dehydration for 48-120 h at 130-137 °C. The polymerization was optimized by varying lactic acid and catalyst concentrations as well as the temperature. Gel permeation chromatography was used to experimentally follow the evolution of molecular weights and the products were characterized by NMR, TGA, DSC and IR. Under optimal conditions, PLLA with weight-average molecular weight (Mw) of 161 kDa could be obtained. The rate equations that describe polycondensation kinetics were recast in a condensed form that allowed very fast numerical solution and calculation of the number-average molecular weight with time. Deviations with respect to the experiment were minimized in a least-squares fashion to determine rate constants. The optimized kinetics parameters are shown to reproduce the experimental data accurately.

Green Hydrogel Synthesis: Emphasis on Proteomics and Polymer Particle-Protein Interaction

The field of drug discovery has seen significant progress in recent years. These advances drive the development of new technologies for testing compound's effectiveness, as well as their adverse effects on organs and tissues. As an auxiliary tool for drug discovery, smart biomaterials and biopolymers produced from biodegradable monomers allow the manufacture of multifunctional polymeric devices capable of acting as biosensors, of incorporating bioactives and biomolecules, or even mimicking organs and tissues through self-association and organization between cells and biopolymers. This review discusses in detail the use of natural monomers for the synthesis of hydrogels via green routes. The physical, chemical and morphological characteristics of these polymers are described, in addition to emphasizing polymer-particle-protein interactions and their application in proteomics studies. To highlight the diversity of green synthesis methodologies and the properties of the final hydrogels, applications in the areas of drug delivery, antibody interactions, cancer therapy, imaging and biomarker analysis are also discussed, as well as the use of hydrogels for the discovery of antimicrobial and antiviral peptides with therapeutic potential.

Polymers Based on PLA from Synthesis Using D,L-Lactic Acid (or Racemic Lactide) and Some Biomedical Applications: A Short Review

Poly(lactic acid) (PLA) is an important polymer that is based on renewable biomass resources. Because of environmental issues, more renewable sources for polymers synthesis have been sought for industrial purposes. In this sense, cheaper monomers should be used to facilitate better utilization of less valuable chemicals and therefore granting more sustainable processes. Some points are raised about the need to study the total degradability of any PLA, which may require specific composting conditions (e.g., temperature, type of microorganism, adequate humidity and aerobic environment). Polymerization processes to produce PLA are presented with an emphasis on D,L-lactic acid (or rac-lactide) as the reactant monomer. The syntheses involving homogeneous and heterogeneous catalytic processes to produce poly(D,L-Lactic acid) (PDLLA) are also addressed. Additionally, the production of blends, copolymers, and composites with PDLLA are also presented exemplifying different preparation methods. Some general applications of these materials mostly dedicated to the biomedical area over the last 10–15 years will be pointed out.

Bioplastics for a circular economy

Bioplastics - typically plastics manufactured from bio-based polymers - stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy, in which virgin polymers are made from renewable or recycled raw materials. Carbon-neutral energy is used for production and products are reused or recycled at their end of life (EOL). In this Review, we assess the advantages and challenges of bioplastics in transitioning towards a circular economy. Compared with fossil-based plastics, bio-based plastics can have a lower carbon footprint and exhibit advantageous materials properties; moreover, they can be compatible with existing recycling streams and some offer biodegradation as an EOL scenario if performed in controlled or predictable environments. However, these benefits can have trade-offs, including negative agricultural impacts, competition with food production, unclear EOL management and higher costs. Emerging chemical and biological methods can enable the 'upcycling' of increasing volumes of heterogeneous plastic and bioplastic waste into higher-quality materials. To guide converters and consumers in their purchasing choices, existing (bio)plastic identification standards and life cycle assessment guidelines need revision and homogenization. Furthermore, clear regulation and financial incentives remain essential to scale from niche polymers to large-scale bioplastic market applications with truly sustainable impact.

Encapsulation of Amikacin into Microparticles Based on Low-Molecular-Weight Poly(lactic acid) and Poly(lactic acid-co-polyethylene glycol)

The aim of this study was to fabricate novel microparticles (MPs) for efficient and long-term delivery of amikacin (AMI). The emulsification method proposed for encapsulating AMI employed low-molecular-weight poly(lactic acid) (PLA) and poly(lactic acid-co-polyethylene glycol) (PLA-PEG), both supplemented with poly(vinyl alcohol) (PVA). The diameters of the particles obtained were determined as less than 30 μm. Based on an in-vitro release study, it was proven that the MPs (both PLA/PVA- and PLA-PEG/PVA-based) demonstrated long-term AMI release (2 months), the kinetics of which adhered to the Korsmeyer-Peppas model. The loading efficiencies of AMI in the study were determined at the followings levels: 36.5 ± 1.5 μg/mg for the PLA-based MPs and 106 ± 32 μg/mg for the PLA-PEG-based MPs. These values were relatively high and draw parallels with studies published on the encapsulation of aminoglycosides. The MPs provided antimicrobial action against the Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae bacterial strains. The materials were also comprehensively characterized by the following methods: differential scanning calorimetry; gel permeation chromatography; scanning electron microscopy; Fourier transform infrared spectroscopy-attenuated total reflectance; energy-dispersive X-ray fluorescence; and Brunauer-Emmett-Teller surface area analysis. The findings of this study contribute toward discerning new means for conducting targeted therapy with polar, broad spectrum antibiotics.

Synthesis, and molecular modeling of bis(3-(piperazine-1-yl)propyl)tungstate (BPPT) nanoparticles, and its first catalytic application for one-pot synthesis of 4H-chromene derivatives

A novel, nano-sized, bis(3-(piperazine-1-yl)propyl)tungstate (BPPT) is introduced as an efficient and reusable organometallic catalyst which is considered as a heterogeneous Bronsted-Lowry base and applied successfully for one-pot synthesis of methyl 2-amino-4-aryl substituted-4H-chromene derivatives with good to excellent yields. BPPT has been prepared via a two-step route from natrium tungstate salt. At first, the oxygens of Na₂WO₄ react with 1-bromo-3-chloropropane via nucleophilic substitution to produce bis(3-choloro propyl)tungstate. Then nucleophilic substitution of piperazine with chlorines produced bis(3-(piperazine-1-yl)propyl) tungstate. Bis(3-(piperazine-1-yl)propyl) tungstate, which was called BPPT, characterized by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and scanning electron microscope (SEM). The catalyst is heterogeneous, green and recyclable. It is a thermally stable and its handling is easy. Its catalytic activity is very high and leads to the production of 4H-pyran derivatives with good to excellent yields in short reaction times. Furthermore, molecular modeling studies and ADMETox prediction revealed that not only it can inhibit acetylcholinesterase enzyme and act as an anti-Alzheimer agent but also has no variation from Lipinski's rule of five and can be a good candidate as anti-Alzheimer agents. These above-mentioned facts can be countered as advantages of the current protocol.