Preparation and characterization of a biodegradable polyester elastomer with thermal processing abilities

We studied the condensing reaction of sebacic acid and glycerol and prepared biodegradable elastomers. Swelling experiments proved that the elastomers were crosslinked polyesters consisting of both insoluble parts (gel) and soluble parts (sol), but the content of sol was higher than gel. X‐ray diffraction analysis showed that some ordered and crystallized structures existed in most of the elastomers. Differential scanning calorimetry measurement showed that there were both crystal regions and amorphous regions with low glass‐transition temperatures in the products, which indicated the elastomers had a microphase separation structure. The elastomers exhibited thermal processing abilities, such as mold‐shaping performance, and a certain elasticity, and hydroxyl, carboxyl, and ester groups in the molecular chains endowed the elastomers with good biodegradation abilities. Furthermore, by altering the molar ratio of the reactants, we were able to adjust the mechanical properties, biodegradable performance, and so on of the elastomers. Glycerol and polymers containing sebacic acid have been approved for biological medical uses by the U.S. Food and Drug Administration, so the elastomers we prepared would have broad application in medical fields such as implants and drug‐delivery systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2033–2041, 2005     

Optimizing mechanical and morphological properties of biodegradable thermoplastic elastomer based on epoxidized natural rubber and poly(butylene succinate) blends

Biodegradable thermoplastic elastomer (BTPE) blends of epoxidized natural rubber (ENR) and poly(butylene succinate) (PBS) were prepared by the melt mixing process. Influences of the processing parameters mixing temperature, rotor speed, and mixing time on mechanical and morphological properties of BTPE were investigated. Taguchi method was applied to improve the mechanical and morphological properties by optimizing the processing parameters. That is, the experimental design adopted the L9 Taguchi orthogonal array with three manipulated factors (i.e., mixing temperature, rotor speed, and mixing time). Analysis of mean and analysis of variance were also exploited and the mixing temperature was found to be the most significant processing parameter regarding mechanical properties. The mixing temperature showed large contributions to Young's modulus, 100% modulus, tensile strength, and elongation at break, namely 45.33, 40.38, 49.31, and 36.04%, respectively. Furthermore, the optimum conditions found for mixing temperature, rotor speed, and mixing time were 140 °C, 100 rpm and 10 min, respectively. The result was confirmed by atomic force microscopy and scanning electron microscopy micrographs showing fine‐grained co‐continuous phase morphology of the ENR/PBS blends. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46541.     

Synthesis and characterization of poly(caprolactone triol succinate) elastomer for tissue engineering application

A novel polymer poly(caprolactone triol succinate) (PPCLSu) was synthesized from monomers polycaprolactone triol and succinic acid by direct polycondensation. The tensile strength of PPCLSu was found to be 0.33 ± 0.03 MPa with an elongation of 47.8 ± 1.9%. These elastomers lost about 7% of their original mass in an in vitro degradation study conducted in phosphate‐buffered saline (PBS) at 37°C up to 10 weeks. Three‐dimensional (3D) porous scaffolds were created by a porogen‐leaching method and these constructs were evaluated for primary rat osteoblast (PRO) proliferation and phenotype development in vitro. This elastomer promoted primary rat osteoblast adhesion, proliferation and increased expression of alkaline phosphatase, an early marker of osteoblastic phenotype. These preliminary results suggest that PPCLSu may be a good candidate material for scaffolding applications in tissue regeneration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3770–3777, 2013     

Lipase‐catalyzed synthesis and characterization of biodegradable polyester containing l‐malic acid unit in solvent system

Lipase‐catalyzed direct polycondensation of L ‐malic acid (L ‐MA), adipic acid, and 1,8‐octanediol in organic media was achieved using Novozym 435 as the biocatalyst. ¹H‐nuclear magnetic resonance spectroscopy indicated that the selectivity of Novozym 435 was unaffected by changes in the organic media. The molecular weight (M_w) of the copolymers was affected by the L ‐MA feed ratio in the diacids, hydrophobicity of the solvent, and solubility of the substrates in the solvents. The M_w reached a maximum of 17.4 kDa at 80°C in isooctane at a L ‐MA feed ratio in the diacids of 40 mol %. The M_w increased from 3.2 to 16.6 kDa when the reaction time was extended from 6 to 48 hr at 70°C, and remained relatively constant with further increases in reaction time from 48 to 72 hr. The hydrophilicity, thermal stability, and crystallizability of the copolymer were also investigated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

可生物降解聚苹果酸丁二醇酯弹性体的制备及表征

以苹果酸和1,4-丁二醇为单体通过熔融缩聚制备出来了一种新型的可生物降解弹性体材料——聚苹果酸丁二醇酯（PBM）,初步研究了材料的亲水性能和降解性能,并对材料的结构进行了初步表征。研究结果表明：PBM的聚集态结构为无定形态,透明柔软,玻璃化转变温度在0℃以下;通过调节合成单体的物质的量比,改变预聚物的后期固化时间,控制后期固化交联（反应）时间等手段,实现了降解性能可控,吸水率可调节的目标。     

Distribution of morphology and transport properties of water vapor in injection‐molded biodegradable aliphatic polyester

A biodegradable polyester, poly(tetramethylene dodecanedioate), was injection molded in a rectangular cavity. Thin sections were sliced from molded samples starting from the skin. The morphology distribution inside the molded samples was studied by X‐ray analysis. The diffusion and solubility coefficient of water vapor were then measured using the microgravimetric method at the temperature of 30°C. Results show that morphology developed during the process influences the diffusion of water molecules through the polymer matrix. In particular, a direct influence of crystalline degree on the sorption and diffusion parameters was identified. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Morphology and properties of poly(ethylene terephthalate) and thermoplastic polyester elastomer blends modified in the melt by a diisocyanate chain extender and filled with a short glass fiber

The structural features and rheological, mechanical, and relaxation properties of poly(ethylene terephthalate) (PET) blends with 7–50 wt % polyester thermoplastic polyester elastomer (TPEE), a block copolymer of poly(butylene terephthalate) and poly(tetramethylene oxide), chemically modified by a diisocyanate chain extender (CE) and reinforced with 30% glass fibers (GF) were studied. The composites were obtained by reactive extrusion with a twin‐screw reactor–mixer with a unidirectional rotation of screws. The molecular–structural changes in the materials were judged against data provided by differential scanning calorimetry, scanning electron microscopy, relaxation spectrometry, and rheological analysis of the melts. Regardless of the TPEE concentration in the blends with GF‐reinforced PET, the addition of CE resulted in the growth of the indices of the mechanical properties at straining, bending, and impact loading and an increase in the melt viscosity. In addition, an increase in the average length of short GFs in the composites and an intensification of interphase adhesion in the polyester binder–GF surface system were observed. The introduction of CE promoted a slowdown in PET crystallization in the composites and intensified the interphase adhesion in the binder–GF system at temperatures higher and lower than the PET glass‐transition temperature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45711.     

Gas permeability of thin dense films from polymer blend of thermoplastic elastomer and polyolefin

Stretched thin films composed of a thermoplastic elastomer, a polystyrene‐block‐poly(ethylene butylene)‐block‐polystyrene triblock copolymer (SEBS), and polyolefins, poly(ethylene‐co‐ethylacrylate) and poly(ethylene‐co‐propylene), were obtained by blow‐molding, uniaxial stretching, and cooling to room temperature and the gas permeability of the stretched films was investigated. When the as‐blown annealed film was subjected to uniaxial stretching in the machine direction, P_O2 and P_N2 increased with an increase in the stretching ratio K and approached a constant value at high stretching ratios. In addition, P_O2/P_N2 decreased gradually with K and approached a value of 2.95–3.0. The reason for this unique gas permeation behavior is that the molecular mobility of poly(ethylene butylene) chains in a direction normal to the film increases and reaches an equilibrium state at around K = 4.5. The change in gas permeability of the stretched films can be explained using a deformation model for the SEBS matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39386.     

Early development of a biodegradable energetic elastomer

The expected depletion of oil resources and a greater awareness for the environmental impact of plastic products have created a strong interest toward energetic polymers that are not only biodegradable but also obtainable from renewable resources. In this work, a copoly(ester/ether) was synthesized from polyepichlorohydrin and sebacoyl chloride using pyridine as a Lewis‐base catalyst. The chlorinated polymer was azidified with NaN₃ in dimethyl sulfoxide solutions. The success of the reaction was confirmed by ¹H‐NMR, ¹³C‐NMR, and Fourier‐transform infrared spectroscopy. Two types of polyurethane networks were synthesized from the nonenergetic and the energetic copolymers, adding polycaprolactone triol and using L ‐lysine diisocyanate as a nontoxic curing agent. The two resulting polyurethanes were soft thermoset elastomers. The polyurethanes were chemically and mechanically characterized, and their biodegradability was evaluated in compost at 55°C. The nonenergetic and the energetic polyurethanes showed a glass‐transition temperature of −14°C, and −23°C, respectively. The weight loss of the polyurethanes during the composting experiments was monitored. It increased almost linearly with time for both materials. After 20 days, the nonenergetic samples lost about 50% of their mass because of the biodegradation mechanism. Instead, the energetic elastomers lost only about 25% of their initial mass after 25 days. The experimental results revealed that the azide pendant group in the soft segment (the polyether segments) is the main factor that controls the physical, mechanical, and degradation properties of these polyurethane networks. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Miscibility of biodegradable aliphatic polyester and poly(vinyl acetate) blends

We report miscibility behavior for synthetic biodegradable aliphatic polyester (BDP) and poly(vinyl acetate) (PVAc) blends by investigating their thermal, rheological, and mechanical properties. Two separate glass transition temperature peaks for the BDP/PVAc blends proved that these blend systems are immiscible. From the rheological measurement, the shear viscosity as a function of shear rate is observed to increase with increasing PVAc content in BDP/PVAc blends, since PVAc has a relatively high molecular weight compared to BDP. Moreover, BDP blends with 10 wt % PVAc have excellent mechanical properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1348–1352, 2000     

Environmental degradation of biodegradable polyesters. IV. The effects of pores and surface hydrophilicity on the biodegradation of poly(ϵ‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] films in controlled seawater

Poly(?‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003     

聚酯型可生物降解弹性体的表征及其降解

用丙三醇和癸二酸通过熔融共缩聚反应合成了具有一定热塑性、可生物降解的弹性体（tp-PGS）,并对其结构进行了表征,同时讨论了该弹性体的力学性能、亲水性能和降解性能。结果表明,tp-PGS属于一种交联网络型聚酯,具有以非晶相为软区、晶相为硬区的微观相分离结构。tp-PGS具有一定程度的热塑性,可模压成型。tp-PGS分子结构中所具有的羟基和酯基赋予其良好的生物降解性能。     

Sulfonamide functionalized amino acid-based pH- and temperature-sensitive biodegradable injectable hydrogels: Synthesis,physicochemical characterization and in vivo degradation kinetics

In this research, a novel pH and temperature-sensitive biodegradable oligomer serin-b-poly(lactide)-b-poly (ethylene glycol)-b-poly(lactide)-b- oligomer serin (OS-PLA–PEG–PLA-OS) pentablock copolymer was synthesized with modification of serine to sulfonamide group. The properties of the different pentablock copolymer structures were detail characterized. The copolymer solution easily flowed at high pH and changed to gel state at physiological conditions (37°C, pH 7.4). The sol to gel behavior of these block copolymer solutions were controllable by tuning the length of PEG segment, PLA/PEG block ratio, the molecular weight and the concentration of the pentablock copolymer. The in vivo gelation of the copolymer solution was investigated. The stable gel was formed after injection into the back of the adult male Mus musculus Swiss Albino mice. The degradation process was observed after 6 weeks and showed that the hydrogel depot was bioresorbable without any detection of inflammation sign. The results in this study suggest that the OS-PLA–PEG–PLA-OS pentablock copolymer has the potential application as an injectable delivery vehicle for therapeutic drugs that easily denatured at low-pH condition.     

Facile fabrication of polyester filament fabric with highly and durable hydrophilic surface by microwave‐assisted glycolysis

Poly(ethylene terephthalate) (PET) fabric with highly and durable hydrophilic surface was fabricated using microwave‐assisted glycolysis. Sodium hydroxide (NaOH) as a catalyst was proven to be suitable for PET glycolysis under assistance of microwave. The modified PET fabric (0.5% NaOH, irradiation 120 s) showed high surface hydrophilicity with a contact angle of 17.4 ° and a wicking length of 19.36 mm. The exposure of the carboxyl‐ and hydroxyl‐end groups on the surface of PET and the introduction of etches were confirmed by Methylene Blue staining and field emission scanning electron microscopy (FESEM), receptively. Although the strength of PET fabric decreased after modification, it was still high enough for textile applications. The thermal properties of the modified PET fabrics were well maintained. The high hydrophilicity and its original properties of PET could be controlled by changing the irradiation time from 60 s to 120 s and adjusting the content of sodium hydroxide from 0.2% to 0.5%. These results suggest microwave‐assisted glycolysis with sodium hydroxide is an effective method for PET hydrophilic finishing. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44069.     

一种新型可生物降解聚酯弹性体的制备及性能

制备了一种新型的、可生物降解聚(癸二酸-甘油-柠檬酸)酯弹性体(PGSC),并对其结构、组成、力学性能、热性能、生物降解性能进行了表征.PGSC弹性体的组成和性能,可以通过控制后期的热交联时间进行调节;而结构中存在的氢键作用,则大大影响了材料的热性能和生物降解性能.该弹性体期望被用作术后防粘连膜、诱导组织再生膜、药物缓释载体等方面.     

Preparation and properties of a novel bio‐based and non‐crystalline engineering elastomer with high low‐temperature and oil resistance

A series of poly(succinic acid/sebacic acid/itaconic acid/butanediol/propanediol) bio‐based and non‐crystalline engineering elastomers (BEE) were obtained by changing the molar ratio of succinic acid (SA) to sebacic acid (SeA) from 5:5 (BEE‐5) to 8:2 (BEE‐8). We prepared bio‐based engineering elastomer composites (BEE/CB) by mixing BEE with carbon black N330. The low‐temperature and oil resistance properties of the BEE/CB composites were investigated in terms of low‐temperature brittleness, coefficient of cold resistance under compression, oil resistance test at different temperatures, and tensile properties. The results showed that the low‐temperature brittleness temperature of the BEE/CB composites ranged from ?50 to ?60°C and the coefficient of cold resistance under compression was 0.18 high at ?60°C for BEE‐7/CB and 0.23 high at ?40°C for BEE‐8/CB. The oil resistance properties of BEE‐7/CB were higher than those of nitrile‐butadiene rubber N240S (NBR N240S), and the oil resistance properties of BEE‐8/CB were even as high as those of nitrile‐butadiene rubber N220S (NBR N220S). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42855.     

Enhanced degradation stability of poly(p‐dioxanone) under different temperature and humidity with bis‐(2,6‐diisopropylphenyl) carbodiimide

The influences on the degradation of poly(p‐dioxanone) (PPDO) under different temperature and relatively humidity is initially investigated by adding bis‐(2,6‐diisopropylphenyl) carbodiimide (commercial name: stabaxol^®‐1). The changes of intrinsic viscosity, mechanical properties, crystallinity, surface morphologies, and microstructure of PPDO and PPDO containing stabaxol^®‐1 for 6 weeks are monitored. With increasing the degradation time, the intrinsic viscosity and mechanical properties of PPDO decrease much faster than those of PPDO containing 0.6 wt % stabaxol^®‐1. During the degradation, PPDO containing 0.6 wt % stabaxol^®‐1 shows a better physical integrity than PPDO. It has been shown that stabaxol^®‐1 can retard the hydrolysis degradation of PPDO and enhance its hydrolytic stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40026.     

Synthesis and characterization of biodegradable low molecular weight aliphatic polyesters and their use in protein‐delivery systems

Poly(lactic acid) (PLA) and poly(lactic‐co‐GA) (PLGA) with low molecular weights were synthesized by a one‐step polycondensation of lactic acid (LA) with glycolic acid (GA) molecules using stannous octoate as a catalyst at 160°C. A high yield (>80%) of all the polymers was obtained in the study. The PLA and PLGA copolymers were characterized by ¹H‐NMR, GPC, and DSC measurements, etc. We elaborated HSA‐loaded microspheres based on PLA and PLGA copolymers with different monomer ratios (LA/GA = 85:15, 75:25, 65:35, and 50:50) by the solvent‐extraction method based on the formation of double w/o/w emulsion. Microspheres were characterized in terms of the morphology, size, and encapsulation efficiency (E.E.). The highest E.E. (69.3%) of HSA was obtained for HSA‐loaded PLGA (65/35) microspheres among all the formulations. In vitro matrix degradation and protein release of these microspheres were performed in phosphate‐buffer saline (PBS; 154 mM, pH 7.4). The degradation profiles were characterized by measuring the loss of the microsphere mass and the decrease of the polymer intrinsic viscosity. The release profiles were investigated from the measurement of the protein presented in the release medium at various intervals. It was shown that the matrix degradation and protein‐release profiles were highly LA/GA ratio‐dependent. It is suggested that these matrix polymers may be optimized as carriers in protein‐ and peptide‐delivery systems for different purposes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1848–1856, 2004     

新型可生物降解弹性体的制备与性能

以聚乙二醇(PEG)和柠檬酸(CA)为单体,通过熔融缩聚制备了新型的可生物降解弹性体聚柠檬酸聚乙二醇〔poly(PEG-co-CA),PEC〕,并通过改变后期交联时间得到了一系列透明柔软的弹性体。用傅里叶变换红外光谱、X射线衍射仪及差示扫描量热仪对PEC进行了初步表征,表明产物在室温下为无定形态,且玻璃化转变温度都在0℃以下;力学性能测试表明所得材料的弹性模量为0.251.91 MPa,扯断伸长率为239.4%1 505.5%;在37℃和pH值为7.4的磷酸缓冲溶液中进行了体外降解实验,结果表明该弹性体为一种降解较快的材料(浸泡80 h后所有试样的降解都超过60%)。同时发现其力学性能、吸水性能和降解性能可通过改变后期交联时间加以调节。