Synthesis and characterization of hydrogels containing biodegradable polymers

BACKGROUND: Amphiphilic block and graft copolymers constitute a very interesting class of polymers with potential for biomedical applications, due to their special characteristics, which derive from the combination of properties of hydrophilic and hydrophobic moieties. In this work, the synthesis and biodegradation of poly(2‐hydroxyethyl methacrylate)‐graft‐poly(L ‐lactide) are studied. RESULTS: The graft copolymers were synthesized using the macromonomer technique. In a first step, methacryloyl‐terminated poly(L ‐lactide) macromonomers were synthesized in a wide molecular weight range using different catalysts. Subsequently, these macromonomers were copolymerized with 2‐hydroxyethyl methacrylate in order to obtain a graft copolymer. These new materials resemble hydrogel scaffolds with a biodegradable component. The biodegradation was studied in hydrolytic and enzymatic environments. The influence of different parameters (molecular weight, crystallinity, ratio between hydrophilic and hydrophobic components) on the degradation rate was investigated. CONCLUSION: Based on this study it will be possible to tailor the release properties of biodegradable materials. In addition, the materials will show good biocompatibility due to the hydrophilic poly(2‐hydroxyethyl methacrylate) hydrogel scaffold. This kind of material has potential for many applications, like controlled drug‐delivery systems or biodegradable implants. Copyright © 2008 Society of Chemical Industry     

Synthesis and in situ foaming of biodegradable malonic acid ESO polymers

In this study, biodegradable rigid cellular materials were synthesized from the reaction of malonic acid with epoxidized soybean oil. Malonic acid reacts with two epoxy groups to give a network polymer. In the course of this reaction, initially formed malonic acid monoester (MAME) can decarboxylate and produce CO₂, which acts as the blowing agent leading to in situ foaming of the polymer. Epoxide addition and decarboxylation reactions of MAME occur competitively and simultaneously and by controlling their relative rates, foams of controlled density were produced. ¹H NMR spectrum of the synthesized foams showed that increasing the temperature increases the rate of decarboxylation reaction of MAME and decreases crosslink density leading to softer and lower density foams. Addition of 1,4‐diazabicyclo[2.2.2]octane (DABCO) as a catalyst also increases the rate of decarboxylation. Load deflection curves of the cellular materials showed that decreasing the temperature and addition of DABCO increase compressive modulus of samples. Cell morphology was studied by microscopic images of foam samples that showed that foam samples have a closed cell structure and a wide distribution of cell volume. Soil burial test was done to determine rate of biodegradation of foam samples. A half‐life of 815 days showed that foam samples are highly biodegradable. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

可生物降解分离膜材料及其应用研究进展

在绿色化学理念的引导下,可生物降解膜材料受到了广泛的关注,有望成为传统分离膜材料的补充和替代品。本文首先分析了传统的不可降解分离膜材料的现状及问题,然后综述了当前较为热门的几种可生物降解膜材料,讨论了它们的发展状况,详细介绍了它们在膜相关领域中的应用,并针对它们的局限性做出了说明并提出了一些解决方案。随后,分析了可生物降解膜材料的生物降解机理,从分子结构角度对膜材料的可生物降解性进行了说明,这将有利于剖析膜材料生物降解的本质,进而平衡膜材料在使用中的稳定性和生物降解性。最后,文章对可生物降解膜材料在发展中遇到的问题进行了展望,并指出随着研究的不断深入,可生物降解膜材料具有广阔的前景和深远的现实意义。     

Quaternary ammonium‐functionalized polymers in biodegradable matrices: Physicochemical properties,morphology, and biodegradability

Quaternary ammonium‐functionalized polymers (QAFPs) based on branched structures of poly(lactic acid) (PLA) and polycaprolactone (PCL) were blended with neat matrices of PLA and PCL to improve their processability in the melt phase at 160 °C. Different formulations were prepared by varying the proportions of the components of the blends (0, 10, 20, 50, and 60 wt % of QAFP). The rheological behavior of each component and their blends was studied at 160 °C and dynamic mechanical analyses were carried out. The thermal properties of the matrices were also investigated by thermogravimetric analyses and differential scanning calorimetry; they were found to be affected by the presence of QAFPs within them. All the studied blends had a dispersed morphology, highlighted by scanning electron microscopy. The water contact angle of the blends was studied and showed that the hydrophilicity of the surfaces of the blends increased by increasing their QAFP content. The biodegradability of both the components and the blends was investigated: a decrease of the biodegradation kinetics was observed due to the presence of the quaternary ammonium groups, but the materials remain biodegradable. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45261.     

Synthesis and evaluation of hyaluronic acid hydrogels modified with various crosslinkers as biodegradable polymers

Hyaluronic acid (HA), a high‐molecular‐weight natural polysaccharide, is often used in medical devices for regenerative medicine as it can undergo biodegradation via enzymatic action in the human body. HA exhibits both viscoelasticity and high biocompatibility and has therefore been used for ocular surgery. In particular, HA‐based hydrogels have been utilized as cell scaffold materials and devices in ophthalmological treatments. In this study, four hydrogels have been synthesized from HA derivatives with methacrylate groups and modified with crosslinkers such as adipic acid dihydrazide, divinyl sulfone, and dithiothreitol. Each of the synthesized hydrogels exhibits high transparency and strength as well as biodegradability in vitro. Hence, these HA‐based hydrogels demonstrate potential for applications as drug delivery systems and implants. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45453.     

Lifetime prediction of biodegradable polymers

The determination of the safe working life of polymer materials is important for their successful use in engineering, medicine and consumer-goods applications. An understanding of the physical and chemical changes to the structure of widely-used polymers such as the polyolefins, when exposed to aggressive environments, has provided a framework for controlling their ultimate service lifetime by either stabilising the polymer or chemically accelerating the degradation reactions. The recent focus on biodegradable polymers as replacements for more bio-inert materials such as the polyolefins in areas as diverse as packaging and as scaffolds for tissue engineering has highlighted the need for a review of the approaches to being able to predict the lifetime of these materials. In many studies the focus has not been on the embrittlement and fracture of the material (as it would be for a polyolefin) but rather the products of degradation, their toxicity and ultimate fate when in the environment, which may be the human body. These differences are primarily due to time-scale. Different approaches to the problem have arisen in biomedicine, such as the kinetic control of drug delivery by the bio-erosion of polymers, but the similarities in mechanism provide real prospects for the prediction of the safe service lifetime of a biodegradable polymer as a structural material. Common mechanistic themes that emerge include the diffusion-controlled process of water sorption and conditions for surface versus bulk degradation, the role of hydrolysis versus oxidative degradation in controlling the rate of polymer chain scission and strength loss and the specificity of enzyme-mediated reactions.     

Effect of pro-oxidants on the aerobic biodegradation,disintegration, and physio-mechanical properties of compostable polymers

Biodegradable polymers are gaining momentum to resolve the globally acknowledged plastic waste problem. Understanding, characterizing, and developing new generations of biodegradable plastics is crucial to provide industries with alternative green materials that can fully satisfy biodegradation rates and lifetime specifications. This study evaluates the influence of metal pro-oxidant additives on the degradation properties of various biodegradable polymer systems. For this purpose, iron (III) stearate (FeSt₃) and bismuth oxide (Bi₂O₃), as oxidant agents, were incorporated into poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(butylene adipate-co-terephthalate) (PBAT), cellulose acetate (CA), poly(lactic acid) (PLA), and thermoplastic starch (TPS) bioplastics. The material performances and biodegradability properties due to the additives on the resulting bioplastic formulations were investigated. A mechanism was proposed in which both pro-oxidant additives can accelerate the thermo-oxidation processes under composting conditions and cleave the polymer chains into smaller fragments to stimulate the biodegradation rate through microorganisms' activity. The study revealed that both pro-oxidant additives, FeSt₃ and Bi₂O₃, effectively improved the biodegradation process for all tested polymers except TPS, which already had a very high biodegradation rate. The observed change in the barrier and mechanical properties due to the additives were within tolerable limits of corresponding neat polymers.     

Recent developments in nanocellulose-based biodegradable polymers,thermoplastic polymers,and porous nanocomposites

Nanocellulose has generated a great deal of interest as a source of nanometer-sized reinforcement, because of its good mechanical properties. In the last few years, nanocellulose has also attracted much attention due to environmental concerns. This review presents an overview of recent developments in this area, including the production, characterization, properties, and range of applications of nanocellulose-based biodegradable polymers, thermoplastic polymers, and porous nanocomposites. After explaining the unique properties of nanocellulose and its various preparation techniques, an orderly introduction of various nanocellulose-reinforced biodegradable polymers such as starch, proteins, alginate, chitosan, and gelatin is provided. Subsequently, the effects of nanocellulose on the properties of thermoplastic polymers such as polyamides, polysulfone, polypropyrol, and polyacronitril are reported. The paper concludes with a presentation of new finding and cutting-edge studies on nanocellulose foam and aerogel composites. Three different types of aerogels, i.e., pristine nanocellulose-based aerogels, modified nanocellulose-based aerogels, and nanocellulose-based templates for aerogels, are discussed, as well as their preparation techniques and properties. In the case of foam composites, the research focus has been on two major preparation techniques, i.e., solvent-mixing/foaming and melt-mixing foaming, their respective challenges, and the properties of the final composites. In some cases, a comparison study between cellulose nanocrystals and cellulose nanofiber-reinforced biodegradable polymers, thermoplastics, and porous nanocomposites was carried out. Considering the vast amount of research on nanocellulose-based composites, special emphasis on such composites isprovided at the end of the review.     

The biodegradation of polymers: Recent results

After a general introduction including definition of biodegradability, the recent literature is briefly summarized. The results obtained in our laboratory for various polymers in three different composting units are then presented. They demonstrate that there is an urgent need for a quantitative method to characterize polymer biodegradation. For that purpose, a manometric method which allows the measurement of the oxygen consumed by the growing microorganisms has been developed. It has been tested with various inocula of increasing complexity: one Streptomyces sp., a mixture of three Streptomyces (badius, setonii and viridosporus), a compost extract or sewer sludge, growing in the presence of low molecular weight molecules as sole carbon source. Its performances and limitations are discussed. It is then applied to various polymer systems: polyesters and their constituent units, autoxidized polyethylene (APE) and its model compounds, polyvinyl alcohol (PVAl), starch and cellulose. The biodegradability of these polymers is characterized and their potential use as biodegradable materials for packaging, sanitary and agricultural uses is discussed.     

An overview of degradable and biodegradable polyolefins

The use of engineering plastics, especially polyolefins has increased significantly in recent decades largely due to their low cost, good mechanical properties and light weight. However, this increase in usage has also created many challenges associated with disposal and their impact on the environment. This is because polyolefins do not easily degrade in the natural environment and hence the need for degradable polyolefins has become a major topic of research. Degradable polyolefins are designed to retain functionality as a commodity plastic for the required service life but degrade to non-toxic end products in a disposal environment. They are typically designed to oxo-degrade while undergoing changes in chemical structure as a result of oxidation in air, thus causing the breakdown of the molecules into small fragments that are then bioassimilated. This article presents (i) a comprehensive review of the chemistry of additives for the degradation of polyolefins, (ii) a patent and scientific literature summary of technologies including commercially available systems, (iii) the mechanisms of degradation and biodegradation, (iv) testing methods and (v) toxicity.     

Mechanical and biodegradation properties of bamboo fiber-reinforced starch/polypropylene biodegradable composites

Bamboo fiber (BF)-reinforced starch/polypropylene (PP) composites were prepared by extrusion and injection molding methods. The mechanical and thermal properties and water absorption were evaluated by different methods. Moreover, composite samples were subjected to biodegradation through soil burial test and microbes medium degradation. Different stages of biodegradation were investigated by weight loss, attenuated total reflection Fourier transformed infrared spectroscopy, differential scanning calorimeter, and scanning electron microscope. It was found that contents of BF and starch resin had a significant influence on the properties of the composites. With more content of BF, the composite exhibited a better flexural property and biodegradation. A distinct decrease of weight loss and mechanical properties indicated the degradation caused by the microbes. After biodegradation, thermal stability of the composites decreased while the crystallinity of PP increased. The results prove that the composites more easily tend to be degraded and assimilated by microbes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48694.     

Development of biodegradable composites with treated and compatibilized lignocellulosic fibers

The aliphatic polyester Bionolle 3020 was combined with lignocellulosic fibers, namely, flax, hemp, and wood, to produce biodegradable composite materials. The effect of two fiber surface treatments, acetylation and propionylation, and the addition of maleic anhydride (MA)‐grafted Bionolle 3001 as a compatibilizer on the fiber/matrix interfacial adhesion was studied. The compatibilizer was synthesized through a MA grafting reaction in the presence of dicumyl peroxide as an initiator. The composites' mechanical properties, water absorption, fracture morphology (scanning electron microscopy), and biodegradation were evaluated. Both the fiber treatments and the compatibilizer incorporation significantly improved the composites' tensile strength, whereas an important reduction in the water absorption was found with the addition of treated fibers. Moreover, fiber incorporation into the matrix increased its biodegradation rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4703–4710, 2006     

The use of biodegradable linear alcohol surfactants in textile wet processing

Highly biodegradable linear alcohol surfactants have proven to be efficient wetting and scouring agents for use in all phases of textile wet processing. The linear alcohol surface active agents can be directly substituted for the conventional alkylphenol-based materials, which have previously been shown to be resistant to biodegradation. No loss in performance or handling characteristics are encountered by changing the surfactant hydrophobe from alkylphenol to linear alcohol. Surfactants based on the linear primary alcohols, which are widely used in biodegradable household detergents, are somewhat less desirable for use with textiles due to generally higher solidification points and less efficient wetting ability. Replacement of branched chain alkylphenol nonionics by more biodegradable linear alcohol ethoxylates has proceeded rather slowly in the textile industry. This is due to various factors, one of which is the reverse relationship between low five-day biochemical oxygen demand (BOD) requirements for industrial waste streams and the higher five-day BOD of the linear alcohol ethoxylates. Continued use of slower degrading alkylphenol ethoxylates is not, however, a satisfactory solution to the problem of the best choice of surfactant. Longer range oxygen demands on receiving waters are shown to exist as a result of such slower biodegradation of these alkylphenol nonionics. One of eight papers being published from the Symposium, “Surface Active Agents in the Textile Industry”, presented at the AOCS Meeting, New Orleans, April 1970.     

可生物降解聚酯的制备及性能研究进展

相对于传统高分子材料,生物降解高分子材料由于其能够在自然环境下降解为环境无害的物质,作为解决塑料白色污染的重要手段之一,近年来获得快速发展。对本课题组生物降解聚酯结构设计、改性及产业化等方面的研究进展进行了总结。通过无规/嵌段共聚的方式在聚二元酸二元醇酯中引入共聚单体单元、长/短支化结构可有效对材料的结晶性能、熔体强度等性能进行调控,进而实现对材料加工性能、力学性能以及生物降解速率的调控。通过对聚合工艺的创新优化,实现高分子量不饱和聚酯的合成,并阐明了其聚合机理;进一步,通过在不饱和聚酯中引入Diels-Alder反应/金属配位活性位点实现可逆交联弹性体的制备。对聚二元酸二元醇酯的结晶结构调控与结晶机理进行了深入的研究,提出了一种基于结晶成核动力学测定高分子结晶次级临界核尺寸的方法;基于类质同晶构型构象匹配设计了新型高效大分子型成核剂。在实验室研究的基础上,与企业合作建成了年产万吨生物降解聚酯及其共聚酯的生产线,生产的产品已应用于一次性餐具、超市购物袋和地膜的制备,并在新疆进行了农田可降解地膜的应用示范。     

Application of 3D-Printed,PLGA-Based Scaffolds in Bone Tissue Engineering

Polylactic acid–glycolic acid (PLGA) has been widely used in bone tissue engineering due to its favorable biocompatibility and adjustable biodegradation. 3D printing technology can prepare scaffolds with rich structure and function, and is one of the best methods to obtain scaffolds for bone tissue repair. This review systematically summarizes the research progress of 3D-printed, PLGA-based scaffolds. The properties of the modified components of scaffolds are introduced in detail. The influence of structure and printing method change in printing process is analyzed. The advantages and disadvantages of their applications are illustrated by several examples. Finally, we briefly discuss the limitations and future development direction of current 3D-printed, PLGA-based materials for bone tissue repair.     

LiClO4 doped cellulose acetate as biodegradable polymer electrolyte for supercapacitors

The possibility of producing a biodegradable polymer electrolyte based on cellulose acetate (CA) with varied concentration of LiClO₄ for use in supercapacitors has been investigated. The successful doping of the CA films has been analyzed by FTIR and DSC measurements of the LiClO₄ doped CA films. The ionic conductivity of the films increased with increase in salt content and the maximum ionic conductivity obtained for the solid polymer electrolyte at room temperature was 4.9 × 10^?3 Ω^?1 for CA with 16% LiClO₄. The biodegradation of the solid polymer electrolyte films have been tested by soil burial, degradation in activated sludge, and degradation in buffer medium methods. The extent of biodegradation in the films has been measured by AC Impedance spectroscopy and weight loss calculations. The study indicated sufficient biodegradability of the materials. A p/p polypyrrole supercapacitor has been fabricated and its electrochemical characteristics and performance have been studied. The supercapacitor showed a fairly good specific capacitance of 90 F g^?1 and a time constant of 1 s. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

超临界流体技术制备生物可降解聚合物/药物纳米微粒研究进展

生物可降解聚合物/药物纳米微粒在药物靶向递送、有效成分封装和医疗诊断等领域具有突出的优势。超临界流体超细微粒制备技术具有绿色环保、制备方法种类多、粒径易调节和后续分离纯化容易等特点,得到了广泛的研究。为了得到满足使用要求的聚合物/药物纳米微粒,超临界流体制粒技术是有效的手段之一。论述了生物可降解聚合物纳米材料的特点和应用情况,简要介绍了超临界流体及特性,重点介绍了超临界溶液快速膨胀(RESS)、超临界抗溶剂沉淀(SAS)、超临界CO₂辅助雾化(SAA)和超临界流体乳液萃取(SFEE)的工艺特点、制备方法、基本原理和研究进展,并对超临界流体技术制备聚合物/药物纳米微粒的发展方向进行了展望。     

Preparation and characterization of biodegradable thermoplastic films based on collagen hydrolyzate

The increasing use of plastics and their nonbiodegradability have raised environmental awareness and hence there is a need for the development of environmentally friendly degradable materials. One of the ways to reach this goal is via the modification of the synthetic polymer, modified polyethylene (MPE), with protein, collagen hydrolyzate (CH). CH is a biopolymer isolated from hide/skin fleshing of untanned solid waste from the leather industry after enzymatic hydrolysis. An investigation on the blending of MPE with CH using polymer melt technique is reported. The resulting thermoplastic films were evaluated using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), and scanning electron microscope (SEM), in addition to simulated soil burial respirometric testing. It is interesting to note that CH easily blends with MPE, but like other biopolymers, it also has effects on the original mechanical properties of the MPE. The CH addition in the blend significantly increases the biodegradation rate. The effect of CH on MPE biodegradability has been investigated. About 53% biodegradation is observed, after 24 days, when the polymer is blended with 5% CH and about 63% biodegradation is found in the case of polymer blended with 20% CH. Although MPE/CH thermoplastic film with 40% CH have shown better performance in biodegradation, the mechanical strength properties were rather poor in this case. The optimum thermoplastic film composition for blending of CH with MPE is about 10–20 wt % CH, which retains an acceptable range of compatibility, mechanical strength, and biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

高吸水性树脂的结构设计与高性能化

综述了影响高吸水性树脂性能的主要因素,介绍了用分子结构设计和形状设计提高其性能的方法。指出SAP的高性能化、复合材料化和可降解性是今后研究的重要发展方向。     

Recent Advances in Food-Packing,Pharmaceutical and Biomedical Applications of Zein and Zein-Based Materials

Zein is a biodegradable and biocompatible material extracted from renewable resources; it comprises almost 80% of the whole protein content in corn. This review highlights and describes some zein and zein-based materials, focusing on biomedical applications. It was demonstrated in this review that the biodegradation and biocompatibility of zein are key parameters for its uses in the food-packing, biomedical and pharmaceutical fields. Furthermore, it was pointed out that the presence of hydrophilic-hydrophobic groups in zein chains is a very important aspect for obtaining material with different hydrophobicities by mixing with other moieties (polymeric or not), but also for obtaining derivatives with different properties. The physical and chemical characteristics and special structure (at the molecular, nano and micro scales) make zein molecules inherently superior to many other polymers from natural sources and synthetic ones. The film-forming property of zein and zein-based materials is important for several applications. The good electrospinnability of zein is important for producing zein and zein-based nanofibers for applications in tissue engineering and drug delivery. The use of zein’s hydrolysate peptides for reducing blood pressure is another important issue related to the application of derivatives of zein in the biomedical field. It is pointed out that the biodegradability and biocompatibility of zein and other inherent properties associated with zein’s structure allow a myriad of applications of such materials with great potential in the near future.