Blends of novel L‐tyrosine‐based polyurethanes and polyphosphate for potential biomedical applications

Elastomeric biodegradable polyurethanes and polyphosphate have been developed using an L ‐ tyrosine‐based diphenolic monomer desaminotyrosine‐tyrosine hexyl ester (DTH). Soft segments, which are polycaproloctone diol (PCL) and polyethylene glycol (PEG) have been used for the synthesis of two biodegradable L ‐tyrosine polyurethanes (LTUs), which are PEG‐C‐DTH and PCL‐C‐DTH. An investigation of the physico‐chemical properties shows that these polymers have dramatically different properties. By blending LTUs with L ‐tyrosine polyphosphate (LTP), we hope to produce a family of materials with a wide range of thermal, morphological, surface, and degradative properties. Examination of the blends shows a smooth surface morphology with a partially phase‐separated structure. These findings are consistent with the results obtained from thermal analysis of the blends. Hydrophilic nature of PEG imparts the PEG‐based blends (PEG‐C‐DTH/LTP) with a significantly higher surface and bulk hydrophilicity compared with the PCL‐based blends (PCL‐C‐DTH/LTP). Finally, the blends demonstrate a rapid initial hydrolytic degradation in phosphate buffered saline (PBS) followed by a significantly slower, prolonged degradation. The observed trend may occur due to the rapid hydrolytic degradation rate of the polyphosphate polymer followed by the degradation of the polyurethane component. Thus, tuning the physical properties by blending LTUs with LTP may be useful for drug delivery device and soft tissue engineering scaffold applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structure‐property relationship of L‐tyrosine‐based polyurethanes for biomaterial applications

The structure‐property relationship of L ‐tyrosine‐based polyurethanes was demonstrated by using different polyols and diisocyanates. L ‐tyrosine‐based chain extender, desaminotyrosyl tyrosine hexyl ester (DTH), was used to synthesize a series of polyurethanes. Polyethylene glycol (PEG) or poly caprolactone diol (PCL) was used as the soft segment and hexamethylene diisocyanate (HDI) or dicyclohexylmethane 4,4′‐diisocyanate (HMDI) was used with DTH as the hard segment. The polyurethanes were characterized to investigate the effect of structure on different polyurethane properties. From FTIR and DSC, these polyurethanes exhibit a wide range of morphology from phase‐mixed to phase‐separated structure. The decreasing molecular weight of the PEG soft segment leads to relatively more phase mixed morphology whereas for PCL‐based polyurethanes the extent of phase mixing is less with decreasing PCL molecular weight. Results show that PCL‐based polyurethanes are mechanically stronger than PEG‐based polyurethanes but PCL‐based polyurethanes degrade slower and absorb less water compared with PEG‐based polyurethanes. The HMDI‐based polyurethanes are less crystalline and comparatively more hydrophobic than HDI‐based polyurethanes. The characterization results show that the polyurethane properties are directly related to the structure and can be varied easily for a different set of properties that are pertinent for biomaterial applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

一种新的可生物降解聚碳酸酯的合成与表征

以天然氨基酸(L-酪氨酸)为原料合成环二肽,以环二肽为单体用光气法合成了属于拟聚氨基酸的聚碳酸酯,该聚合物的结构特点为主链肽键与非肽键重复排列,其主链结构中既有水解键又有酶解键。差示扫描量热法、热重分析法和凝胶渗透色谱法的分析结果显示,聚合物的玻璃化转变温度低于100℃,热降解温度在300℃以上,聚合物多分散度为1.338。X射线衍射结果表明,合成的聚合物为无定形物。     

聚碳酸酯的热降解

综述了聚碳酸酯的热稳定性及其影响因素,并详细论述了一些添加剂如偶联剂甲基三甲氧基硅烷、钛酸四丁酯、阻燃剂二苯砜磺酸钾(KSS)、聚氨丙基苯基倍半硅氧烷(PAPSQ)等对聚碳酸酯热稳定性的影响,阐述了Kissinger法和Ozawa法等聚合物热降解动力学的分析方法。重点介绍了近期国内外有关聚碳酸酯热降解产物和热降解机理方面的研究成果。     

Synthesis and characterization of novel biodegradable poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s

Poly(p‐dioxanone‐co‐ethyl ethylene phosphate)s were successfully synthesized by the ring‐opening copolymerization of p‐dioxanone and ethyl ethylene phosphate with triisobutyl aluminum as an initiator; this was confirmed by ¹H‐NMR and infrared spectra. The effects of the reaction conditions, such as the feeding ratio of the monomers and the reaction temperature and time, on the molecular weight of the copolymers were also studied. The in vitro degradation results showed that the introduction of phosphate segments into the backbone chains of the copolymers led to an enhancement of the degradation rate of the copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5507–5511, 2006     

Synthesis,characterization, and soil biodegradation study of polyamides derived from the novel bioactive diacid monomer 5‐(2‐phthalimidoethanesulfonamido) isophthalic acid

A new bioactive diacid monomer, 5‐(2‐phthalimidoethanesulfonamido) isophthalic acid ( 6 ), was synthesized in three steps. This monomer can be regarded as biologically active aromatic diacid and may be used in the design of biodegradable and biological materials. This monomer was polymerized with several aromatic diamines by step‐growth polymerization to give a series of biodegradable and highly thermally stable polyamides (PAs) with good yield (70–82%) and moderate inherent viscosity between 0.38–0.68 dL/g in a system of triphenylphosphite/pyridine/N‐methyl‐2‐pyrolidone/CaCl_2. The new aromatic diacid 6 and all of the PAs derived from this diacid and aromatic diamines were characterized by Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and elemental analysis techniques. The thermal stability of the PAs was determined by thermogravimetric analysis and differential scanning calorimetry techniques under a nitrogen atmosphere, and we found that they were moderately stable. The soil biodegradability behavior of 6 and all of the PAs derived from this diacid and aromatic diamines were investigated in culture media, and we found that the synthesized diacid 6 and all of the PAs were biodegradable under a natural environmental. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of the biomaterial poly(lactic acid‐co‐Nε‐carbobenzoyloxy‐L‐lysine) via direct melt copolymerization

With D,L ‐lactic acid and N^ϵ‐carbobenzoyloxy‐L ‐lysine [Lys(Z)] as the starting monomer material and tin dichloride as the catalyst, the drug carrier material poly(lactic acid‐co‐N^ϵ‐carbobenzoyloxy‐L ‐lysine) was synthesized via direct melt polycondensation. The copolymer was systematically characterized with intrinsic viscosity testing, Fourier transform infrared spectroscopy, ¹H‐NMR, gel permeation chromatography, differential scanning calorimetry, and X‐ray diffraction. The influences of different feed molar ratios were examined. With increasing molar feed content of Lys(Z), the intrinsic viscosity, weight‐average molecular weight, and polydispersity index (weight‐average molecular weight/number‐average molecular weight) gradually decreased. Because of the introduction of Lys(Z) with a big aromatic ring into the copolymer, the glass‐transition temperature gradually increased with increasing feed charge of Lys(Z), and all of the copolymers were amorphous. The copolymers, with weight‐average molecular weights from 10,500 to 6900 Da, were obtained and could reach the molecular weight level of poly(lactic acid) modified by Lys(Z) via the ring‐opening polymerization of the cyclic intermediates, such as lactide and morpholine‐2,5‐dione. However, a few terminal carboxyl groups might have been deprotected during the polymerization reaction under high temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(L‐lactide). X. Enhanced surface hydrophilicity and chain‐scission mechanisms of poly(L‐lactide) film in enzymatic,alkaline, and phosphate‐buffered solutions

Attempts were carried out to enhance the surface hydrophilicity of poly(L ‐lactide), that is, poly(L ‐lactic acid) (PLLA) film, utilizing enzymatic, alkaline, and autocatalytic hydrolyses in a proteinase K/Tris–HCL buffered solution system (37°C), in a 0.01N NaOH solution (37°C), and in a phosphate‐buffered solution (100°C), respectively. Moreover, its chain‐scission mechanisms in these different media were studied. The advancing contact‐angle (θ_a) value of the amorphous‐made PLLA film decreased monotonically with the hydrolysis time from 100° to 75° and 80° without a significant molecular weight decrease, when enzymatic and alkaline hydrolyses were continued for 60 min and 8 h, respectively. In contrast, a negligible change in the θ_a value was observed for the PLLA films even after the autocatalytic hydrolysis was continured for 16 h, when their bulk M_n decreased from 1.2 × 10⁵ to 2.2 × 10⁴ g mol^?1 or the number of hydrophilic terminal groups per unit weight increased from 1.7 × 10^?5 to 9.1 × 10^?5 mol g^?1. These findings, together with the result of gravimetry, revealed that the enzymatic and alkaline hydrolyses are powerful enough to enhance the practical surface hydrophilicity of the PLLA films because of their surface‐erosion mechanisms and that its practical surface hydrophilicity is controllable by varying the hydrolysis time. Moreover, autocatalytic hydrolysis is inappropriate to enhance the surface hydrophilicity, because of its bulk‐erosion mechanism. Alkaline hydrolysis is the best to enhance the hydrophilicity of the PLLA films without hydrolysis of the film cores, while the enzymatic hydrolysis is appropriate and inappropriate to enhance the surface hydrophilicity of bulky and thin PLLA materials, respectively, because a significant weight loss occurs before saturation of θ_a value. The changes in the weight loss and θ_a values during hydrolysis showed that exo chain scission as well as endo chain scission occurs in the presence of proteinase K, while in the alkaline and phosphate‐buffered solutions, hydrolysis proceeds via endo chain scission. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1628–1633, 2003     

Fully renewable limonene‐derived polycarbonate as a high‐performance alkyd resin

Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO₂, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (T_g) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher T_g in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry     

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.     

Synthesis and characterization of PMMA composites activated with starch for immobilization of L‐asparaginase

Poly (methyl methacrylate) (PMMA)–starch composites were prepared by emulsion polymerization technique for L‐asparaginase (L‐ASNase) immobilization as highly activated support. The hydroxide groups on the prepared composites offer a very simple, mild and firm combination for enzyme immobilization. The pure PMMA and PMMA‐starch composites were characterized as structural, thermal and morphological. PMMA‐starch composites were found to have better thermal stability and more hydrophilic character than pure PMMA. L‐ASNase was immobilized onto PMMA‐starch composites contained the different ratio of starch (1, 3, 5, and 10 wt %). Immobilized L‐ASNase showed better performance as compared to the native enzyme in terms of thermal stability and pH. K_m value of immobilized enzyme decreased approximately eightfold compared with the native enzyme. In addition to, immobilized L‐ASNase was found to retain 60% of activity after 1‐month storage period at 4 °C. Therefore, PMMA‐starch composites can be provided more advantageous in terms of enzymatic affinity, thermal, pH and storage stability as L‐ASNase immobilization matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43421.     

Synthesis and characterization of novel copolymers with acid‐labile ketal moieties derived from camphor

Novel diastereomeric acrylic ketal monomers derived from (+)‐camphor and (±)‐camphor were synthesized. To investigate the applications of the camphor derivatives on positive‐tone photoresists, the acrylic ketal monomers were copolymerized with methyl methacrylate, methacrylic acid, and n‐butyl methacrylate. The optical activities of the chiral monomers and polymers were all evaluated. After UV irradiation and postexposure baking, the optical activity of the polymers decreased because of the decomposition of the acid‐labile pendant chiral groups. The existence of alicyclic camphyl groups increased the etching resistance of the photoresists. The thermogravimetric properties of the copolymers, the exposure curves, the lithographic evaluation of the positive‐tone photoresists, and the effects of alicyclic groups on the plasma etching resistance of the copolymers were all investigated. A resolution of a line‐and‐space pattern of 0.3 μm was achieved. Acid‐catalyzed dehydration crosslinking was also found in this system. Sufficient UV irradiation and heat treatment could cause the acid‐catalyzed dehydration crosslinking of pendant carboxyl groups and thereby increase the efficiency of the thermal resistance of the polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2969–2978, 2003     

Synthesis,characterization, and thermal degradation kinetic of polystyrene‐g‐polycaprolactone

In the present study, it has been demonstrated that polystyrene‐g‐polycaprolactone (PS‐g‐PCL) was successfully prepared by “click chemistry.” For this purpose, first, poly(styrene‐co‐4‐chloromethylstyrene) (P(S‐co‐CMS)) with 4‐chloromethylstyrene content (10%) was synthesized. Second, alkyne‐functionalized polycaprolactone (PCL) was obtained using propargyl alcohol and caprolactone. P(S‐co‐CMS) and PCL were reacted in N,N‐dimethylformamide for 24 h at 25°C to give PS‐g‐PCL. The synthesized polymer was characterized by nuclear magnetic resonance (¹H‐NMR), gel permeation chromatography, Fourier transform infrared spectroscopy and thermogravimetric analysis. The apparent activation energies for thermal degradation of PS‐g‐PCL were obtained by differential (Kissenger) and integral methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Tang, Coats–Redfern, Van Krevelen et al.). The decomposition mechanism and pre‐exponential factor were calculated in terms of Coats–Redfern method. The most likely decomposition processes of first and second degradation stages were A_n type and F₃ type, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of a redox‐initiated,injectable, biodegradable hydrogel

A chemically crosslinked biodegradable hydrogel was prepared via a macromer technique, and physicochemical characterizations associated with its potential application as an injectable biomaterial were carried out. The macromers were composed of poly(ethylene glycol) extended with oligomers of biodegradable polyesters such as oligolactide and end‐capped with acryloyl groups. Hydrogels were obtained through the polymerization of the macromer aqueous solutions in phosphate‐buffered saline initiated by a redox initiator system at body temperature. The initiator system was composed of ammonium persulfate as an initiator and N,N,N′,N′‐tetramethylethylene diamine as an accelerator. The modulus of this chemical gel was much higher than that of a Pluronic physical gel. In vitro biodegradation was also confirmed. The degradation rates were highly tunable by the adjustment of several factors, such as the kind of ester group, the block length of the oligoester, and even the concentration of the accelerator used in the crosslinking reaction. The gelation time could be adjusted to meet the requirements of an injectable biomaterial. The effect of the polymerization heat seemed not to be significant. This kind of biodegradable hydrogel might be in situ formed after being injected into the body and shows potential applications as a unique tissue engineering material free of porogening techniques in scaffold fabrication and less invasive in implantation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Degradation of poly(L‐lactide) by a mesophilic bacterium

A Gram negative, rod‐shaped mesophilic bacterium active for poly(L ‐lactide) (PLA) degradation was isolated through the enrichment culture and clear‐zone method. The isolated strain was identified to be Bordetella petrii PLA‐3 on the basis of 16S rDNA gene sequence analysis. B. petrii PLA‐3 was active not only for the degradation of low‐molecular‐weight PLA but also for the degradation of high‐molecular‐weight PLA. The strain seemed to attack the crystalline part of PLA as well as the amorphous region. The PLA film incubated in compost inoculated with the isolated strain lost its weight more notably and exhibited a lower molecular weight than that incubated in the sterilized compost without living microorganisms. Moreover, the profile of the cumulative amount of CO₂ after 20 days of burial in the sterilized compost and subsequent inoculation of the isolated strain into compost was nearly the same as that of CO₂ evolved from PLA buried in compost with the isolated strain at the very beginning when the time was shifted by 20 days. This indicated that not only the abiotic hydrolysis but also the microbial enzymes of the strain contributed to the initial chain cleavage of PLA molecules and resolved the doubt that PLA molecules should be initially cleaved into very low‐molecular‐weight substances by abiotic hydrolysis to be subsequently absorbed into and biodegraded by microorganisms. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of biodegradable block copolymer pluronic‐b‐poly(L‐lysine)

This study presented the investigations on the synthesis of a novel biodegradable block copolymer of pluronic‐b‐poly(L ‐lysine) (pluronic‐b‐PLL), which combined the characteristics of aliphatic polyester and poly(amino acids). The synthesis work started with end‐capping of pluronic with N‐t‐butoxycarbonyl‐L ‐phenylalanine using dicyclohexylcarbodiimide in the presence of 4‐dimethylaminopyridine, followed by a deprotection process to obtain the amino‐terminated pluronic; the new primary amino group in the modified pluronic initiated ring‐opening polymerization of amino acid N‐carboxyanhydride, which afforded the pluronic‐b‐poly(N^ε‐(Z)‐L ‐lysine) block copolymer. Finally, removal of the side‐chain N^ε‐(carbonybenzoxy) end protecting groups yields the block copolymer of pluronic‐b‐PLL. The products were characterized by ¹H‐NMR, FTIR, DSC, and GPC. The block copolymer micelle containing the anticancer drug paclitaxel was prepared by the double emulsion method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and degradation behavior of poly(propylene carbonate) derived from carbon dioxide and propylene oxide

High molecular weight and regular molecular structure poly(propylene carbonate) (PPC) was successfully synthesized from carbon dioxide and propylene oxide. The PPC copolymer structure was an exact alternating copolymer as evidenced by the ¹³C‐NMR technique. Degradative behavior of the PPC was conducted by soil burial and buffer solution immersion (pH = 6) tests, respectively. The results showed that the weight loss of soil buried in PPC films increased more slowly than that immersed in the buffer solution after 6‐month exposure. However, the weight loss of sample immersed in the buffer solution increased rapidly during the first 2 months and reached a value of 4.59%. Water sorption measurement also revealed that the PPC membranes immersed in buffer solution were more hydrophilic than those in soil burial tests. The degradation mechanism of PPC membranes was correlated with the sample morphologies, FTIR, and ¹H‐NMR spectra. The SEM morphologies were consistent with the weight loss and water sorption measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1840–1846, 2004     

Synthesis,characterization, and hydrolytic degradation of copolyesters of 3‐(4‐hydroxyphenyl) propionic acid and p‐hydroxybenzoic acid,vanilic acid,or syringic acid

A series of copolyesters were prepared by a direct polycondensation of 3‐(4‐hydroxyphenyl) propionic acid and p‐hydroxybenzoic acid (HBA), vanilic acid (VA), or syringic acid (SGA) of different composition in pyridine using diphenyl chlorophosphate and lithium bromide as condensing agents. The effects of methoxy substitution in the benzene ring and copolymer composition on the synthesis and thermal properties as well as hydrolytic degradation were examined. The methoxy substitution increased a glass transition temperature and a solubility, while it decreased a crystallinity and a thermal stability. The HBA series copolyesters showed a homogenous nematic phase, while the VA and SGA series copolyestes neither revealed an anisotropic melt nor formed a mobile melt below around 350°C. The hydrolytic degradation of melt‐pressed films was performed in a 5% sodium hydroxide aqueous solution at 40°C to test a biodegradability of the copolyesters. HBA‐50 and HBA‐30 exhibited the much higher degradation rate than HBA‐70, showing that the aliphatic ester linkage was more degradable than aromatic one. The degradation rates of VA‐50 and SGA‐50 were remarkably slower than that of HBA‐50 due to the steric hindrance of the methoxy group in the ortho position. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2474–2481, 2000     

Chitosan‐comb‐graft‐polyethylene glycol monomethacrylate—Synthesis,characterization, and evaluation as a biomaterial for hemodialysis applications

Chitosan was reacted with “Polyethylene glycol monomethacrylate” (PEGm) using a redox initiation method. Different compositions were prepared by varying the relative amount of PEGm in the feed. A maximum of 88% yield with 320% grafting could be achieved. The graft copolymerization was confirmed by FTIR, thermal, and XRD studies. Higher graft % could be achieved as the monomer used is a macro monomer of PEG and the resultant graft is a comb‐like polymer. Grafting with PEGm did not affect the thermal stability of chitosan film significantly, however, it resulted in a marginal increase in the tensile strength of the films in the dry state. The products showed much improved swelling at pH 7.4 and pH 1.98 compared to the virgin chitosan. The preliminary biocompatibility evaluation showed that the materials are blood compatible and non‐cytotoxic. Though the permeability to low molecular weight solutes like creatinine and glucose was equal to or better than commercial cellulose membranes, the copolymer films expressed comparatively less permeability to these solutes initially, due to the crystalline domains of PEO grafts that impede the transport. On exposure in the medium, this effect is nullified culminating in better permeability. The crystallization of PEG grafts was very helpful in preventing the permeation of the high molecular weight solute albumin, the leakage of which above a certain limit is dangerous to the patient. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Environmental factors and kinetics of microbial degradation of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) in an aqueous medium

Environmental factors such as oxygen, temperature, and microbial species may have significant effects on decomposition of biodegradable polymers. A representative biodegradable, thermoplastic polymer, poly(3‐hydroxybutyrate‐co‐hydroxyvalerate) (PHBV), was decomposed in an aqueous medium under controlled laboratory conditions by soil microbes for the intrinsic degradation kinetics and the effects of the environmental factors on polymer biodegradation. The amount of proteins, including the PHBV depolymerases, that attached to the polymer surfaces was quite constant during the period of significant mass loss of the polymer specimens. The microbial polymer degradation followed a zero‐order rate model, so the residual mass fraction of PHBV films declined linearly with time. The mixed aerobic microbial organisms from fertile soil showed a higher activity of polymer degradation than an aerobic PHBV‐producing bacterium and the mixed anaerobes in the same soil. The mixed anaerobic microorganisms from barren soil decomposed the polymer at a slower rate than the anaerobes from fertile soil, and this was attributed to fewer microbial cells in the barren soil instead of the difference in the microbial species. The temperature effect on PHBV degradation can be described with an Arrhenius equation, and the activation energy is around 16 kcal/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 205–213, 2003