Polymer Degradation Research Articles

Simple Genomic Traits Predict Rates of Polysaccharide Biodegradation.

Natural and chemically modified polysaccharides are extensively employed across a wide array of industries, leading to their prevalence in the waste streams of industrialized societies. With projected increasing demand, a pressing challenge is to swiftly assess and predict their biodegradability to inform the development of new sustainable materials. In this study, we developed a scalable method to evaluate polysaccharide breakdown by measuring microbial growth and analyzing microbial genomes. Our approach, applied to polysaccharides with various structures, correlates strongly with well-established regulatory methods based on oxygen demand. We show that modifications to the polysaccharide structure decreased degradability and favored the growth of microbes adapted to break down chemically modified sugars. More broadly, we discovered two main types of microbial communities associated with different polysaccharide structures─one dominated by fast-growing microbes and another by specialized degraders. Surprisingly, we were able to predict biodegradation rates based only on two genomic features that define these communities: the abundance of genes related to rRNA (indicating fast growth) and the abundance of glycoside hydrolases (enzymes that break down polysaccharides), which together predict nearly 70% of the variation in polysaccharide breakdown. This suggests a trade-off, whereby microbes are either adapted for fast growth or for degrading complex polysaccharide chains, but not both. Finally, we observe that viral elements (prophages) encoded in the genomes of degrading microbes are induced in easily degradable polysaccharides, leading to complex dynamics in biomass accumulation during degradation. In summary, our work provides a practical approach for efficiently assessing polymer degradability and offers genomic insights into how microbes break down polysaccharides.

The Recyclability of Fire-Retarded Biobased Polyamide 11 (PA11) Composites Reinforced with Basalt Fibers (BFs): The Influence of Reprocessing on Structure, Properties, and Fire Behavior.

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer's burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described.

Application Analysis of Biodegradable Polymer Materials in Food Packaging

With the rapid development of biotechnology, the society pays more attention than in the past to the production and development of environmental protection. Choosing materials has always been a more important part of environmental protection work, among them, the degradable polymer materials are also professional research topics, it can be self-degradation under certain conditions, with far-reaching environmental protection value and social significance. Food packaging is a kind of carrier that plays a protective role in packaging, preservation and sales of food, the application of degradable polymer materials in food packaging can play a positive role in environmental protection, reducing environmental pollution and building an ecological society. In this paper, the active application of biodegradable polymer materials for food packaging is elaborated, hoping to provide theoretical reference.

An in-depth study of the oxidative liquefaction process for polymeric waste reduction and chemical production from wind turbine blades and personal protective equipment used in the medical field

An in-depth study of the oxidative liquefaction process has been provided to degrade the polymeric waste from personal protective equipment (PPEs) and wind turbine blades (WTBs). Thermogravimetric investigations demonstrate that WTBs have three prominent peaks throughout the degradation, whereas PPEs display solitary peak features. Experiments are carried out employing specific experimental design approaches, namely the Central Composite Face-Centered Plan (CCF) for WTBs and the Central Composition Design with Fractional Factorial Design for PPEs in a batch-type reactor at temperature ranges of 250–350 °C, pressures of 20–40 bar, residence times of 30–90 min, H2O2 concentrations of 15–45 %, and waste/liquid ratios of 5–25 % for WTBs. These values were 200–300 °C, 30 bar, 45 min, 30–60 % and 5–7 % for PPE. A detailed comparison has been provided in the context of total polymer degradation (TPD) for PPE and WTBs. Liquid products from both types of wastes after the oxidative liquefaction process are subjected to gas chromatography with flame ionization detection (GC-FID) to identify the existence of oxygenated chemical compounds (OCCs). For WTBs, TPD was 20–49 % and this value was 55–96 % for PPE while the OCC yield for WTBs (36.31 g/kg - 210.59 g/kg) and PPEs (39.93 g/kg - 212.66 g/kg) was also calculated. Detailed optimization of experimental plans was carried out by performing the analysis of variance (ANOVA) and optimization goals were maximum TPD and OCCs yields against the minimum energy consumption, though a considerable amount of complex polymer waste can be reduced and high concentrations of OCC can be achieved, which could be applied for commercial and environmental benefits.

Effect of monovalent/divalent ions and SiO2-based nanocomposite dosage on thermochemical stability of HPAM polymeric solutions

This study evaluated the effect of monovalent and divalent ions and the dosage of a SiO2-based nanocomposite on the thermochemical stability of HPAM polymeric solution. Chelating Amine–Functionalized NPs (AFNPs) were used to enhance the thermochemical stability of HPAM based on capturing monovalent/divalent ions after seven days at 70°C. Different polymer solutions prepared with calcium chloride dihydrate (CaCl2·2H2O) at 2000 mg/L and sodium chloride (NaCl) at 10000 mg/L, and two different dosages of HPAM (1000 and 2000 mg/L) were assessed in the presence and absence of AFNPs at dosages of 200, 500 and 1000 mg/L. The nanocomposite was characterized by N2 adsorption, Fourier-transformed infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA), dynamic Light Scattering (DLS), and Zeta potential (ZP). Stability tests over time confirmed the positive effect of nanocomposite on increasing the thermochemical stability of polymer solutions. Results revealed that adding 0, 200, and 500 mg/L of nanocomposite to the polymeric solution at 1000 mg/L of HPAM, 10000 mg/L of NaCl, and 2000 mg/L of CaCl2·2H2O led to the viscosity reductions of 73.5%, 18%, and less than 1% after 7 days (70°C), respectively. Nanocomposite at 200 mg/L reduces the polymer degradation in the presence of the two salts evaluated separately, i.e., 20% for 10000 mg/L of NaCl and 15% for 2000 mg/L of CaCl2·2H2O. The adsorption tests on AFNPs and SiO2 NPs concluded that AFNPs had higher adsorption of cations in comparison to SiO2 NPs and that greater adsorption of cations is related to a reduction in polymer degradation.

Bridging gap between agro-industrial waste, biodiversity and mycelium-based biocomposites: Understanding their properties by multiscale methodology

A multiscale methodology approach was employed integrating microscopic analysis of the biomasses present in the biocomposite (lignocellulosic and fungal) to understand their macroscopic response in terms of physical and mechanical properties. Colombian native strain Ganoderma gibbosum, used for the first time in the production of biocomposites was cultivated on peach palm fruit peel flour and sugar cane bagasse wet dust, individually and as a mixture. During the solid-state fermentation were monitoring the change that occurred in substrate composition such as glucan, arabinoxylan, and lignin through biomass compositional analysis using structural carbohydrates and lignin. Moreover, fungal biomass formation was monitored via scanning electron microscopy. The resulting biocomposites underwent characterization through flexural and water absorption tests. Our findings indicated that G. gibbosum primarily degraded the polysaccharides in each of the evaluated media. However, lignin degradation to 15.06 g/g was only observed in the mixture biocomposite of peach palm fruit peel fluor and sugarcane bagasse wet dust in a ratio of 1꞉1, accompanied by a reduction in glucan and arabinoxylan weights to 26.1 and 7.72 g/g, respectively. This polymer degradation, combined with a protein-rich source in the mixture biocomposite of peach palm fruit peel fluor and sugarcane bagasse wet dust in a ratio of 1꞉1, facilitated the production of a fungal skin (biological matrix) with a high hyphal density of 65%, contributing to Young's modulus of 3.83 MPa, elongation without failure, and low water absorption rate in this biocomposite (55%). The lignocellulosic biomass in the culture media acted as a filler for mechanical interlocking with the matrix and provided attachment points for water absorption. Thus, our study establishes a connection between the microscopic scale and the macroscopic behavior of this biocomposite, assessing structural carbohydrates and lignin analysis during solid-state fermentation (SSF), laying the groundwork for a more customized design of mycelium-based biocomposites. Finally, this study demonstrates the possibility of tailoring nutrient composition by designing their culture media to obtain physical-mechanical properties according to the application requirement.

Synthesis of degradable porous polymers by ring-opening addition of a tri-aziridine and thiol-carboxylic acids

Synthesis of degradable porous polymers by ring-opening addition of a tri-aziridine and thiol-carboxylic acids

Creation of fully degradable and mechanically robust poly(4-hydroxybutyrate) films by filling modified starch

Chemically synthesized poly(4-hydroxybutyrate) (P4HB) is a new generation of biomass-derived and degradable semi-crystalline polymer with good comprehensive properties, but high costs limit its application. Starch, as an inexpensive natural polymer, can reduce the cost of P4HB products. However, starch lacks thermoplastic behavior and has poor compatibility with P4HB, thus its extensive use will inevitably impair the mechanical properties of P4HB. In this study, the ball-milling starch grafting process is adopted, which can simultaneously solve the two major deficiencies of starch, and the prepared ball-milling starch-g-polycaprolactone (BSt-g-PCL) has thermoplasticity and better compatibility with P4HB. BSt-g-PCL can melt near 55 °C, and the interweaving of its molecular chains with P4HB reduces the binding energy (Einteraction) of both, making the phase interface blurred or even disappear. Therefore, the elongation at break retention (REB) of P4HB/BSt-g-PCL can increase from 37.1 % to 74.3 % compared to P4HB/starch at the same filling (70 Phr). Additionally, BSt-g-PCL can exert the effect of accelerating P4HB degradation and still make it maintain excellent anti-aging ability. The ball-milling starch graft process provides a simple and effective method for the preparation of inexpensive fully biodegradable P4HB composite films with excellent mechanical properties.

Electroactive additives into polyurethanes for high corrosion resistance coatings for mild steel

AbstractThere is a demand for innovative coatings such as polyurethane (PU) in industrial and commercial sectors to effectively combat corrosion on mild steel substrates. In this work, novel redox‐active polyurea (PUr) additives such as PUr‐diamine capped trimer (DCTA) and PUr‐diamine‐capped tetraaniline (DCTAni), derived from DCTA and DCTAni, were synthesized to enhance the anticorrosion properties of PU coatings. These are characterized using 1H nuclear magnetic resonance spectroscopy, Fourier transformed infrared, and high‐resolution mass spectrometry technical methods. These additives (2, 5, and 10 wt%) were dispersed in a polyurethane‐urea (PUU) matrix, which was synthesized from PTMG‐2000, and IPDI with dihydrazide adipate as a chain extender. The electroactivity of the coatings were evaluated using cyclic voltammetry (CV) and ultraviolet–visible spectroscopy. Furthermore, anticorrosion performance was assessed through electrochemical impedance spectroscopy and Tafel potentiodynamic polarization measurements. The optimal corrosion protection was achieved with increasing weight percent (wt%) of additive in PUU, showing a trend of 10% > 5% > 2%. Coatings reported maximum polarization resistance (Rp) of 122.15 MΩ, with corrosion rates (CR) as low as 2.38 × 10−6 mm/year. Accelerated salt spray testing over 600 h in a 5 wt% NaCl salt fog confirmed the coatings' durability. The microstructures of PUr particles were determined through FESEM characterization. Additive‐blended PUUs exhibited moderate tensile strength and elongation at break compared to the reference PUU matrix. The hydrophobicity of both the reference sample (PUU) and the additive‐blended coatings was measured, with the highest recorded value being at 93.1 ± 0.048 for 10 wt%. Thermal gravimetric analysis demonstrated polymer degradation with a maximum of T5% observed at 304.1°C.

Effectiveness of degradable polymer film in the management of severe or moderate intrauterine adhesions (PREG-2): a randomized, double-blind, multicenter, stratified, superiority trial

To study the effectiveness of a new intrauterine degradable polymer film (Womed Leaf®) in the management of moderate to severe IUA. PREG2 study was a multi-centre, double-blind, randomised, controlled, stratified, two-arm superiority clinical trial conducted in 16 centres in 7 countries. Patients ≥18 years scheduled for hysteroscopic adhesiolysis because of symptomatic severe or moderate adhesions (according to American fertility society (AFS) IUA score) were considered eligible for the study. Following adhesiolysis, patients were randomised at a 1:1 ratio to either have a Womed Leaf film inserted (intervention group) or not (control group). The primary effectiveness endpoint of the study was the change in AFS IUA score on second-look hysteroscopy (SLH), assessed by an independent evaluator, compared to baseline. Information on rate of no IUA and responder rate were collected as secondary effectiveness outcomes, and reported adverse events and patient reported outcomes as safety and tolerability measures. Between October 26, 2021, and September 28, 2023, a total of 160 women were randomised (Womed Leaf: n=75 and controls: n=85). The reduction in IUA AFS score on SLH was significantly higher in the intervention compared to the control group (mean 5.2 ± 2.8 vs. 4.2 ± 3.2; p=0.0153). Similarly, the absence of adhesions on SLH was significantly higher in the intervention group (41% vs 24% OR 2.44 [CI 1.161 - 5.116]; p=0.0189). None of the reported adverse events were serious or considered related to the device. Womed Leaf is effective and safe in the management of symptomatic severe or moderate intrauterine adhesions.

The Advances in Phospholipids-Based Phase Separation Gels for the Sustained Release of Peptides, Proteins, and Chemotherapeutics.

Implantable drug delivery systems formed upon injection offer a host of advantages, including localized drug administration, sustained release, minimized side effects, and enhanced patient compliance. Among the various techniques utilized for the development of in situ forming drug implants, solvent-induced phase inversion emerges as a particularly promising approach. However, synthetic polymer-based implants have been associated with undesirable effects arising from polymer degradation. In response to this challenge, a novel category of drug delivery systems, known as phospholipids-based phase separation gels (PPSGs), has emerged. These gels, characterized by their low initial viscosity, exhibit injectability and undergo rapid transformation into in situ implants when exposed to an aqueous environment. A typical PPSG formulation comprises biodegradable components, such as phospholipids, pharmaceutical oil, and a minimal amount of ethanol. The minimized organic solvents in the composition show good biocompatibility. And the relatively simple composition holds promise for industrial-scale manufacturing. This comprehensive review provides an overview of the principles and advancements in PPSG systems, with specific emphasis on their suitability as drug delivery systems for a wide range of active pharmaceutical ingredients (APIs), spanning from small molecules to peptides and proteins. Additionally, we explore the critical parameters and underlying principles governing the formulation of PPSG-based drug delivery strategies, offering valuable insights on optimization strategies.

Tetrazine-based dynamic covalent polymers as degradable extraction materials in sample preparation

BackgroundCurrent trends in Analytical Chemistry are highly focused on the introduction of new extraction materials with a high selectivity towards the target analytes, high extraction capacity as well as sustainable characteristics. In this context, the introduction of smart materials able to respond to an external stimulus constitutes a promising approach in the field. However, investigations regarding the development of such stimuli-responsive polymers have been basically centered on their synthesis and the control of their properties, and hardly on exploiting such properties to generate polymers that, once their extraction function is fulfilled, they can be degraded into fragments with little or negligible toxicity, or even into their constituent monomers for an efficient recycling. ResultsThe applicability of a degradable and recyclable dynamic covalent polymer based on the use of tetrazine as a linker was assessed as sorbent for the extraction of a group of 37 persistent organic pollutants, including 10 polycyclic aromatic hydrocarbons, 11 organochlorine pesticides, 14 polychlorinated biphenyls, and 2 antibacterial agents, from water samples. A microdispersive solid-phase extraction procedure was developed for the selective extraction of the target analytes, while their separation, determination, and quantification were achieved by gas chromatography coupled to mass spectrometry. The optimized procedure was validated for seawater and wastewater obtaining mean relative recovery values between 72 and 112 % for almost all the analytes, with satisfactory relative standard deviation values (<18 %). After extraction, the polymer could be degraded by adding the amino acid L-tyrosine, being possible a quantitative recovery of the initial functional monomer. SignificanceA responsive polymer based on the chemical versatility of the tetrazine ring was used as sorbent in sample preparation providing excellent results, showing good physicochemical properties and the ability to be degraded after use. This polymer constitutes an interesting alternative to reduce chemical waste through the recycling of monomers, contributing to the development of more sustainable analytical methodologies.

Enzyme induced polymer degradation as a pathway to create microbial habitats for biomanufacturing intensification

Polymer hydrogels are instrumental in cell immobilization for biomanufacturing, yet traditional hydrogel bioreactors often compromise cell viability, function, and mass transfer. This results in uncontrolled microbial proliferation and significant cell leakage, thereby impeding the continuous production of high-value products. To address these challenges, we introduce an innovative liquid microcavity technique employing a blend of Gelatin-methacryloyl (Gel-MA) and Pluronic F127diacrylate (F127-DA) for precision bioprinting, followed by selective enzymatic digestion of gelatin to create microbial habitats. Through tailoring of the hydrogel’s pore structure and integration of diverse networks, our approach facilitates controlled nutrient transfer, efficient waste removal, and stable mechanical support, all while maintaining a leak-free suspension culture of microorganisms. We validated the effectiveness of our method by fabricating yeast-infused Three-dimensional (3D) lattice constructs, successfully achieving continuous fermentation of glucose into ethanol in a flow reactor with minimal efficiency reduction (≥90 % yield) over five cycles. This research not only confronts the spatial limitations inherent in hydrogel-based systems but also demonstrates a foundational potential for revolutionary change in biomanufacturing practices.

Physiology and comparative genomics of the haloalkalitolerant and hydrocarbonoclastic marine strain Rhodococcus ruber MSA14.

Marine hydrocarbonoclastic bacteria can use polycyclic aromatic hydrocarbons as carbon and energy sources, that makes these bacteria highly attractive for bioremediation in oil-polluted waters. However, genomic and metabolic differences between species are still the subject of study to understand the evolution and strategies to degrade PAHs. This study presents Rhodococcus ruber MSA14, an isolated bacterium from marine sediments in Baja California, Mexico, which exhibits adaptability to saline environments, a high level of intrinsic pyrene tolerance (> 5g L- 1), and efficient degradation of pyrene (0.2g L- 1) by 30% in 27 days. Additionally, this strain demonstrates versatility by using naphthalene and phenanthrene as individual carbon sources. The genome sequencing of R. ruber MSA14 revealed a genome spanning 5.45 Mbp, a plasmid of 72 kbp, and three putative megaplasmids, lengths between 110 and 470 Kbp. The bioinformatics analysis of the R. ruber MSA14 genome revealed 56 genes that encode enzymes involved in the peripheral and central pathways of aromatic hydrocarbon catabolism, alkane, alkene, and polymer degradation. Within its genome, R. ruber MSA14 possesses genes responsible for salt tolerance and siderophore production. In addition, the genomic analysis of R. ruber MSA14 against 13 reference genomes revealed that all compared strains have at least one gene involved in the alkanes and catechol degradation pathway. Overall, physiological assays and genomic analysis suggest that R. ruber MSA14 is a new haloalkalitolerant and hydrocarbonoclastic strain toward a wide range of hydrocarbons, making it a promising candidate for in-depth characterization studies and bioremediation processes as part of a synthetic microbial consortium, as well as having a better understanding of the catabolic potential and functional diversity among the Rhodococci group.

Acetal‐thiol Click‐like Reaction: Facile and Efficient Synthesis of Dynamic Dithioacetals and Recyclable Polydithioacetals

AbstractDithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst‐ and solvent‐free acetal‐thiol click‐like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal‐thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio‐sourced furan‐acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto‐protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals with w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi‐interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3‐mercaptopropionate). This green and high‐efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry.

Acetal-thiol Click-like Reaction: Facile and Efficient Synthesis of Dynamic Dithioacetals and Recyclable Polydithioacetals.

Dithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst- and solvent-free acetal-thiol click-like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal-thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio-sourced furan-acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto-protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals with w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi-interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3-mercaptopropionate). This green and high-efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry.

Durable lightweight cementitious composites incorporating rice husk: Accelerated aging studies with acidic and basic solutions

This study investigates the compatibility between cellular concrete (foamed concrete) and natural rice husk to develop high-performance and sustainable sealing materials. Through a bibliographical review we identified challenges in incorporating vegetable fibers into cementitious matrices due to problems related to durability. Prismatic samples of a Reference mixture (foamed concrete) and a Composite with foamed concrete and natural rice husk underwent chemical treatments with acidic and basic solutions to simulate long-term durability. Results show that even after complete organic matter degradation, the composite maintains adequate mechanical performance for sealing walls. Microstructural analyses, including scanning electron microscopy, x-ray diffraction, x-ray fluorescence, and energy dispersive spectroscopy, revealed that silica in the rice husk significantly contributes to axial compression strength by forming C–S–H. The degradation of natural polymers results in the formation of calcium carbonate and calcium sulfate dihydrate, mitigating strength loss. This study proves that the composites with natural rice husk and foamed concrete are a viable and durable solution, provided it does not include metallic materials susceptible to corrosion in composition.

Influence of the processing parameters on the degradation of poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and modification of their molecular weight using chain extenders

Poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) exhibit valuable mechanical properties like high stiffness and tensile strength but are sensitive to processing parameters. The influence of these parameters was evaluated by measuring the variation of melt viscosity during processing. For all experiments, in the absence of chain extenders, the decrease in melt viscosity clearly showed the degradation of polymers during processing. This is more pronounced for PHBV than PLA. In order to compensate for the degradation and, if possible, improve the melt strength of these bio-based polymers, two chain extenders have been evaluated: dicumyl peroxide (DCP) and a polymeric epoxy acrylate chain extender (Joncryl® ADR 4400). DCP reacts quickly with PLA and PHBV, while the epoxy-acrylate chain extender shows slower kinetics. For the PLA, with both investigated chain extenders, an increase in the molecular weight as compared with the virgin polymer and eventually the apparition of an insoluble fraction due to branching and crosslinking are observed. In the case of PHBV, the degradation is compensated by using DCP, requiring short processing times. No significant increase in molecular weight was observed when using the polymeric epoxy acrylate chain extender, requiring longer residence times, although the apparition of a gel fraction suggests the presence of branching and crosslinking.

Environmentally Degradable Polymers Incorporating Stimuli‐Triggered Cleavable Linkages toward Industrial Materials

AbstractPlastics designed to degrade upon exposure to ambient stimuli after use are emerging as promising alternatives to conventional plastics, considering environmental pollution. The so‐called “biodegradable polymers,” which can be degraded by enzymes or microbes, are the most reliable biodegradable polymers, and considerable effort is devoted to their practical application. Several other examples are also developed for the cleavage of chemical bonds in macromolecules, as one part of a vast variety of “stimuli‐responsive polymers,” especially for biomedical applications. These chemical insights provide a design concept that can even be extended to plastic materials. Here, stimuli‐cleavable linkages, drawing from the chemical insights cultivated in biomedical fields, intended for application in degradable plastics, are outlined. As stimuli for polymer degradation, pH changes, photoirradiation, and redox conditions are selected because polymers released in natural environments may inadvertently be exposed to these stimuli. The degradation pathways are grouped into five categories: 1) stimuli‐cleavable linkages, 2) self‐amplifying, 3) self‐immolative, 4) chain shattering, and 5) double responsive. The classification and organization of the stimuli‐cleavable linkages provide insights for designing new, degradable polymers.

Lipid-Polymer Nanoparticles Mediate Compartmentalized Delivery of Cas9 and sgRNA for Glioblastoma Vasculature and Immune Reprogramming.

Hypervascularized glioblastoma is naturally sensitive to anti-angiogenesis but suffers from low efficacy of transient vasculature normalization. In this study, a lipid-polymer nanoparticle is synthesized to execute compartmentalized Cas9 and sgRNA delivery for a permanent vasculature editing strategy by knocking out the signal transducer and activator of transcription 3 (STAT3). The phenylboronic acid branched cationic polymer is designed to condense sgRNA electrostatically (inner compartment) and patch Cas9 coordinatively (outer compartment), followed by liposomal hybridization with angiopep-2 decoration for blood-brain barrier (BBB) penetration. The lipid-polymer nanoparticles can reach glioblastoma within 2h post intravenous administration, and hypoxia in tumor cells triggers charge-elimination and degradation of the cationic polymer for burst release of Cas9 and sgRNA, accompanied by instant Cas9 RNP assembly, yielding ≈50% STAT3 knockout. The downregulation of downstream vascular endothelial growth factor (VEGF) reprograms vasculature normalization to improve immune infiltration, collaborating with interleukin-6 (IL-6) and interleukin-10 (IL-10) reduction to develop anti-glioblastoma responses. Collectively, the combinational assembly for compartmentalized Cas9/sgRNA delivery provides a potential solution in glioblastoma therapy.