High yield synthesis of biodegradable poly(propylene carbonate) from carbon dioxide and propylene oxide

A novel SalenCo^III (2,4‐dinitrophenoxy) (Salen = N,N'‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediamino) and 1,10‐phenanthroline monohydrate catalyst system was designed and employed for the copolymerization of CO₂ and propylene oxide (PO). The perfectly alternating copolymerization of CO₂ and PO proceeds effectively under middle temperature and pressure to yield poly(propylene carbonate) with a high yield and a high number average molecular weight of polymer. The structure of polymer was characterized by the IR and NMR measurements. The perfectly alternating copolymer was confirmed. The MALDI‐TOF spectrum insinuates that the copolymerization of CO₂ and PO was initiated by H₂O. Copyright © 2016 John Wiley & Sons, Ltd.     

Copolymerization of carbon dioxide and propylene oxide by several metallosalen‐based bifunctional catalysts

A series of new metallosalen‐based bifunctional catalysts with Co(III), Cr(III), Fe(III), Mn(III), and Ni(III) were synthesized for the first time, and a detailed study on the mechanism of the copolymerization of CO₂ and propylene oxide (PO) was performed. Meanwhile, the impact factors of the reaction conditions (metal cations, temperature, CO₂ pressure, and reaction time) on catalytic activity and selectivity were investigated. The results indicated that, with the increase of temperature, both the catalyst efficiency and the molecular weight of the copolymer decrease for all the five complexes. The salen‐Co(III) complex demonstrated higher activity under mild conditions: reaction temperature at 30 °C, copolymerization time of 24 hr, and 2 MPa of CO₂ pressure. The DSC curve indicated that the PPC by the salen‐Co(III) complex has the highest T_g of 46.19 °C. DTGA curves demonstrated that there were two thermal degradation peaks: the first is for the ester bond, and the second is for the C C bond.     

Copolymerization of propylene oxide with carbon dioxide catalyzed by zinc adipate

Copolymerization of carbon dioxide with propylene oxide in the presence of zinc adipate was studied. The effects of the temperature, nature of the solvent, and catalyst concentration on the molecular weight, molecular-weight distribution, and yields of the copolymer and propylene carbonate were examined. The structure of the polymer obtained was studied by ¹³N and ¹I NMR spectroscopy.     

Novel,biodegradable, functional poly(ester‐carbonate)s by copolymerization of trans‐4‐hydroxy‐L‐proline with cyclic carbonate bearing a pendent carboxylic group

Water‐soluble poly(ester‐carbonate) having pendent amino and carboxylic groups on the main‐chain carbon is reported for the first time. This article describes the melt ring‐opening/condensation reaction of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L ‐proline (N‐CBz‐Hpr) with 5‐methyl‐5‐benzyloxycarbonyl‐1,3‐dioxan‐2‐one (MBC) at a wide range of molar fractions. The influence of reaction conditions such as catalyst concentration, polymerization time, and temperature on the number average molecular weight (M_n) and molecular weight distribution (M_w/M_n) of the copolymers was investigated. The polymerizations were carried out in bulk at 110 °C with 3 wt % stannous octoate as a catalyst for 16 h. The poly(ester‐carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR, differential scanning calorimetry, and gel permeation chromatography. The copolymers synthesized exhibited moderate molecular weights (M_n = 6000–14,700 g mol^?1) with reasonable molecular weight distributions (M_w/M_n = 1.11–2.23). The values of the glass‐transition temperature (T_g) of the copolymers depended on the molar fractions of cyclic carbonate. When the MBC content decreased from 76 to 12 mol %, the T_g increased from 16 to 48 °C. The relationship between the poly(N‐CBz‐Hpr‐co‐MBC) T_g and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N‐CBz‐Hpr‐co‐MBC)s was evaluated from weight‐loss measurements and the change of M_n and M_w/M_n. Debenzylation of 3 by catalytic hydrogenation led to the corresponding linear poly(ester‐carbonate), 4 , with pendent amino and carboxylic groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2303–2312, 2004     

Water‐soluble poly(ethylene oxide)‐block‐poly(p‐phenylene vinylene) copolymer: Synthesis and characterization

Water‐soluble and photoluminescent block copolymers [poly(ethylene oxide)‐block‐poly(p‐phenylene vinylene) (PEO‐b‐PPV)] were synthesized, in two steps, by the addition of α‐halo‐α′‐alkylsulfinyl‐p‐xylene from activated poly(ethylene oxide) (PEO) chains in tetrahydrofuran at 25 °C. This copolymerization, which was derived from the Vanderzande poly(p‐phenylene vinylene) (PPV) synthesis, led to partly converted PEO‐b‐PPV block copolymers mixed with unreacted PEO chains. The yield, length, and composition of these added sequences depended on the experimental conditions, namely, the order of reagent addition, the nature of the monomers, and the addition of an extra base. The addition of lithium tert‐butoxide increased the length of the PPV precursor sequence and reduced spontaneous conversion. The conversion into PPV could be achieved in a second step by a thermal treatment. A spectral analysis of the reactive medium and the composition of the resulting polymers revealed new evidence for an anionic mechanism of the copolymerization process under our experimental conditions. Moreover, the photoluminescence yields were strongly dependant on the conjugation length and on the solvent, with a maximum (70%) in tetrahydrofuran and a minimum (<1%) in water. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4337–4350, 2005     

Toughening of poly(propylene carbonate) by carbon dioxide copolymer poly(urethane-amine) via hydrogen bonding interaction

A carbon dioxide copolymer poly(urethane-amine)(PUA) was blended with poly(propylene carbonate)(PPC) in order to improve the toughness and flexibility of PPC without sacrificing other mechanical properties. Compared with pure PPC, the PPC/PUA blend with 5 wt% PUA loading showed a 400% increase in elongation at break, whilst the corresponding yielding strength remained as high as 33.5 MPa and Young's modulus showed slightly decrease. The intermolecular hydrogen bonding interaction in PPC/PUA blends was comfirmed by FTIR, 2D IR and XPS spectra analysis, and finely dispersed particulate structure of PUA in PPC was observed in the SEM images, which provided good evidence for the toughening mechanism of PPC.     

Amphiphilic block poly(propylene carbonate)‐block‐allyloxypolyethyleneglycol copolymer based shell cross‐linked micelles for controlled release of drug

Amphiphilic block poly(propylene carbonate)‐block‐allyloxypolyethyleneglycol (PPC‐b‐APEG) copolymer was synthesized by the click chemistry, and its structure were characterized. PPC‐b‐APEG can self‐assemble into micelles without emulsifier in water. Shell cross‐linked micelles were obtained by the reaction of the allyloxy groups, which were exposed on the outer of the PPC‐b‐APEG micelles, and N‐vinylpyrrolidone (NVP). The morphology and size of the micelles before and after cross‐link reactions were characterized. The research result shows that the shell cross‐linking could improve the stability of micelles. The particle size of uncross‐linked micelle was about 800 nm. The size of cross‐linked micelles increased with increasing amount of cross‐linking degree. To better evaluate the release behavior of PPC‐b‐PEG copolymer, doxorubicin (DOX)‐loaded micelles were synthesized using DOX as the model drug. Results showed that the DOX releasing rate decreased with increasing of NVP. The shell cross‐linking do decrease the burst release behaviours of DOX and reduce the DOX release rate.     

Crosslinkable poly(propylene carbonate): High‐yield synthesis and performance improvement

A crosslinking strategy was used to improve the thermal and mechanical performance of poly(propylene carbonate) (PPC): PPC bearing a small moiety of pendant C?C groups was synthesized by the terpolymerization of allyl glycidyl ether (AGE), propylene oxide (PO), and carbon dioxide (CO₂). Almost no yield loss was found in comparison with that of the PO and CO₂ copolymer when the concentration of AGE units in the terpolymer was less than 5 mol %. Once subjected to UV‐radiation crosslinking, the crosslinked PPC film showed an elastic modulus 1 order of magnitude higher than that of the uncrosslinked one. Moreover, crosslinked PPC showed hot‐set elongation at 65 °C of 17.2% and permanent deformation approaching 0, whereas they were 35.3 and 17.2% for uncrosslinked PPC, respectively. Therefore, the PPC application window was enlarged to a higher temperature zone by the crosslinking strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5329–5336, 2006     

Synthesis of propylene carbonate from carbon dioxide using trans‐dichlorotetrapyridineru‐ thenium(II) as catalyst

trans‐Dichlorotetrapyridineruthenium(II) [trans‐RuCl₂(py)₄] was synthesized and the structure was determined by single crystal X‐ray crystallography. Highly efficient formation of propylene carbonate (PC) from carbon dioxide and propylene oxide was achieved by using a catalyst system composed of trans‐RuCl₂(py)₄ and hexadecyl trimethyl ammonium bromide under mild conditions (4h, 80 °C, 3.0 MPa). PC was obtained in nearly 100% selectivity without the formation of a polymer. The catalyst could be recycled constantly many times without any significant loss of its catalytic activity. On the basis of the results, a mechanism for the reaction was proposed. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

From poly(N‐isopropylacrylamide)‐block‐poly(ethylene oxide)‐block‐poly(N‐isopropylacrylamide) triblock copolymer to poly(N‐isopropylacrylamide)‐block‐poly(ethylene oxide) hydrogels: Synthesis and rapid deswelling and reswelling behavior of hydrogels

Poly(N‐isopropylacrylamide)‐block‐poly(ethylene oxide)‐block‐poly(N‐isopropylacrylamide) (PNIPAAm‐b‐PEO‐b‐PNIPAAm) triblock copolymer was synthesized via the reversible addition‐fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) process with xanthate‐terminated poly(ethylene oxide) (PEO) as the macromolecular chain transfer agent. The successful synthesis of the ABA triblock copolymer inspired the preparation of poly(N‐isopropylacrylamide)‐block‐poly(ethylene oxide) (PNIPAAm‐b‐PEO) copolymer networks with N,N′‐methylenebisacrylamide as the crosslinking agent with the similar approach. With the RAFT/MADIX process, PEO chains were successfully blocked into poly(N‐isopropylacrylamide) (PNIPAAm) networks. The unique architecture of PNIPAAm‐b‐PEO networks allows investigating the effect of the blocked PEO chains on the deswelling and reswelling behavior of PNIPAAm hydrogels. It was found that with the inclusion of PEO chains into the PNIPAAm networks as midblocks, the swelling ratios of the hydrogels were significantly enhanced. Furthermore, the PNIPAAm‐b‐PEO hydrogels displayed faster response to the external temperature changes than the control PNIPAAm hydrogel. The accelerated deswelling and reswelling behaviors have been interpreted based on the formation of PEO microdomains in the PNIPAAm networks, which could act as the hydrophilic tunnels to facilitate the diffusion of water molecules in the PNIPAAm networks. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Alternating copolymerization of carbon dioxide and propylene oxide under bifunctional cobalt salen complexes: Role of Lewis base substituent covalent bonded on salen ligand

Alternating copolymerization of propylene oxide (PO) and carbon dioxide (CO₂) was realized under mild conditions with a moderate turnover frequency (TOF), employing sole bifunctional cobalt salen complexes containing Lewis acid metal center and covalent bonded Lewis base on the ligand. Variation of the covalent bonded Lewis base substituents on the salen ligands could tailor the catalytic activity with TOF changing from 19.3 to 34.9 h^?1, polymeric/cyclic carbonate selectivity from 95.3 to 72.8%, and the head‐to‐tail structure in the polymer from 72.2 to 86.0%. The IR analysis confirmed that the Lewis base moiety on one molecule could coordinate with cobalt center of adjacent molecule, playing similar role to the Salen metal complex/Lewis base binary catalytic system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 359–365, 2010     

Alternating copolymerization of propylene oxide and carbon dioxide with highly efficient and selective (salen)Co(III) catalysts: Effect of ligand and cocatalyst variation

Synthetic routes to a series of new (salen)CoX (salen = N,N′-bis(salicylidene)-1,2-diaminoalkane; X = Br or pentafluorobenzoate (OBzF₅)) species are described. Several of these complexes are active for the copolymerization of propylene oxide (PO) and CO₂, yielding regioregular poly(propylene carbonate) (PPC) without the generation of propylene carbonate byproduct. Variation of the salen ligand, as well as the inclusion of organic-based ionic or Lewis basic cocatalysts, has dramatic effects on the resultant (salen) CoX catalytic activity. Highly active (R,R)-(salen- 1 )CoOBzF₅ (salen- 1 = N,N′-bis(3,5- di-tert-butylsalicylidene)-1,2-diaminocyclohexane) catalysts with [Ph₄P]Cl or [PPN]Y ([PPN] = bis(triphenylphosphine)iminium; Y = Cl or OBzF₅) cocatalysts exhibited turnover frequencies up to 720 h⁻¹ for rac-PO/CO₂ copolymerization, yielding PPC with greater than 90% head-to-tail connectivity. Additionally, the (R,R)-(salen- 1 )CoOBzF₅/[PPN]Cl catalyst system demonstrated a k_rel of 9.7 for the enchainment of (S)- over (R)-PO when the copolymerization was carried out at low temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5182–5191, 2006     

Synthesis,characterization, and properties of poly(ester‐phosphoester)s by lanthanum triphenolate‐catalyzed ring‐opening copolymerization

The ring‐opening copolymerization of methyl ethylene phosphate (MEP, 2‐methoxy‐2‐oxo‐1,3,2‐dioxaphospholane) and ε‐caprolactone (CL) was performed in bulk with lanthanum tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s as single‐component catalyst, resulting in poly(ester‐phosphoester) random copolymers with high molecular weight and moderate molecular weight distribution. The properties of the copolymers were characterized by differential scanning calorimetry, X‐ray diffractometer, dynamic mechanical analysis, and static water contact angle measurement. The crystallinities of the copolymers were reduced with the increase of MEP molar fraction in the products. Moreover, copolymers with enhanced hydrophilicity and lower glass transition temperature could be obtained with higher MEP content, which may provide potential applications in biomedical field. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Photocrosslinked poly(ester‐anhydride) microspheres with macroporous structure

In this work, the new method of preparation biodegradable microspheres with macroporous structure is presented. Typical methods used for generation of porous structures in microspheres obtained from preformed polymers require the use of additional substances acting as porogens. In this study, the porosity was achieved as the effect of photocrosslinking, without porogens. Microspheres were prepared using emulsion solvent evaporation technique from functional poly(ester‐anhydride)s with different amount of allyl groups in the side chains. The crosslinking was carried out by UV irradiation during the solvent evaporation (photoinitiator was introduced to polymer solution). The size of microspheres obtained was in the range of 1.7 – 4 µm (small microspheres) or 31 – 50 µm (large ones) and depended on the conditions used in emulsion formulation process. Effectiveness of the crosslinking was characterized by the content of insoluble part of samples, and it was in the range of 42–89%. The content of insoluble part of sample of microspheres and their porosity were dependent on functionality of poly(ester‐anhydride)s, the amount of photoinitiator used, and also on size of microparticles. The small particles were always more crosslinked than the large ones, but the latter were more porous than the small ones. Crosslinked microparticles indicated higher loading efficiency of model compound and appeared to degrade faster than uncrosslinked ones, probably due to their high porosity. The high porosity of microspheres obtained would enable their eventual use in pulmonary drug delivery systems or in construction of porous scaffolds for tissue engineering. Copyright © 2013 John Wiley & Sons, Ltd.     

Emulsion copolymerization of D,L‐lactide and glycolide in supercritical carbon dioxide

Biodegradable polyesters were synthesized via an emulsion polymerization in supercritical carbon dioxide (SC‐CO₂). Copolymers of lactide and glycolide were synthesized in SC‐CO₂ with stannous octoate as the ring‐opening catalyst and a fluorocarbon polymer surfactant as an emulsifying agent. The conversion of lactide and glycolide was monitored with respect to the reaction time and temperature with ¹H NMR spectroscopy. The conversion of glycolide surpassed 99% within 72 h for an SC‐CO₂ phase maintained at 200 bar and 70 °C. Under the same conditions, lactide conversion reached 65% after 72 h of polymerization. Unpolymerized monomer was removed after the reaction by extraction with an SC‐CO₂ mobile phase. The molecular weights of all the copolymers were measured by gel permeation chromatography. Weight‐average molecular weights (M_w) ranged between 2500 and 30,200 g/mol and polydispersity indices ranged from 1.4 to 2.3 for polymerization times of 6 and 48 h, respectively. Although the molecular weight increased significantly during the first 48 h of reaction, there was no significant difference in the M_w for polymerization times of 48 and 72 h. Emulsion polymerization within the benign solvent SC‐CO₂ demonstrated improved conversion and molecular weight versus polymers synthesized without surfactant. The emulsion polymerization of lactide and glycolide copolymers in SC‐CO₂ is proposed as a novel production technique for high‐purity, biodegradable polymers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 562–570, 2001     

Characterization of polysuccinate and hydroxyapatite‐based nanocomposites containing poly(ester‐anhydride) microspheres

Repair and regeneration of bone defects with particular shape may be enhanced by in situ forming biomaterials which can be used in minimal invasive surgery. This study is aimed to prepare novel in situ forming biodegradable nanocomposites based on poly(3‐allyloxy‐1,2‐propylene) succinate (PSAGE) and nanosized hydroxyapatite (HA). These nanocomposite materials contain poly(ester‐anhydride) (PEA) microspheres embedded in a polyester matrix prepared by crosslinking PSAGE with oligo(1,2‐propylene maleate) and methacrylic monomers. Methyl methacrylate and one of hydrophilic oligo(ethylene glycol) methacrylates with different functionality and various length of oligooxyethylene chains were used as polymerizable diluents. Incorporation of microspheres which degrade faster than crosslinked polyester matrices enables formation of porous structure in situ. The obtained materials are liquid before curing and harden in several minutes with moderate exothermic effect. The effect of the composition of nanocomposite materials on selected properties, such as water sorption, mechanical strength, porosity and hydrolytic degradation process, was investigated. Rheological behavior and injectability of liquid formulations were studied. Analysis by energy dispersive spectroscopy confirmed the presence of characteristic features of HA in the nanocomposite materials. The morphology of the cured nanocomposites subjected to hydrolytic degradation was evaluated by scanning electron microscopy. The MTS cytotoxicity assay was carried out for extracts from crosslinked materials using hFOB1.19 cells. It was found that the extracts exhibit a dose‐dependent cytotoxic response. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel poly(ester‐carbonate)s by copolymerization of trans‐4‐hydroxy‐L‐proline with cyclic carbonate

The melt ring‐opening/condensation reaction of trans‐4‐hydroxy‐N‐benzyloxycarbonyl‐L‐proline (N‐CBz‐Hpr) with cyclic carbonate [trimethylene carbonate (tri‐MC) or tetramethylene carbonate (tetra‐MC)] at a wide range of molar fractions in the feed produced new degradable poly(ester‐carbonate)s. The influence of reaction conditions such as polymerization time and temperature on the yield and inherent viscosity of the copolymers was investigated. The polymerizations were carried out in bulk at 140 °C with 1.5 wt % stannous octoate as a catalyst for 30 h. The poly(ester‐carbonate)s obtained were characterized by Fourier transform infrared spectroscopy, ¹H NMR, differential scanning calorimetry, gel permeation chromatography, and Ubbelohde viscometry. The copolymers synthesized exhibited moderate molecular weights with rather narrow molecular weight distributions. The values of the glass‐transition temperature (T_g) of the copolymers depend on the molar fractions of cyclic carbonate. For the poly(N‐CBz‐Hpr‐co‐tri‐MC) system, with a decreased tri‐MC content from 93 to 16 mol %, the T_g increased from ?10 to 60 °C. Similarly, for the poly(N‐CBz‐Hpr‐co‐tetra‐MC) system, when the tetra‐MC content decreased from 80 to 8 mol %, the T_g increased from ?18 to 52 °C. The relationship between the poly(N‐CBz‐Hpr‐co‐tri‐MC) T_g and the compositions was in approximation with the Fox equation. In vitro degradation of these poly(N‐CBz‐Hpr‐co‐tri‐MC)s was evaluated from weight‐loss measurements. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1435–1443, 2003     

Regio‐regular structure high molecular weight poly(propylene carbonate) by rare earth ternary catalyst and Lewis base cocatalyst

Lewis base modification strategy on rare earth ternary catalyst was disclosed to enhance nucleophilic ability of active center during copolymerization of carbon dioxide and propylene oxide (PO), poly(propylene carbonate) (PPC) with H‐T linkages over 83%, and number–average molecular weight (M_n) up to 100 kg/mol was synthesized at room temperature using Y(CCl₃OO)₃‐ZnEt₂‐glycerine catalyst and 1,10‐phenanthroline (PHEN) cocatalyst. Coordination of PHEN with active Zinc center enhanced the nucleophilic ability of the metal carbonate, which became more regio‐specific in attacking carbon in PO, leading to PPC with improved H‐T linkages. Moreover, the binding of PHEN to active Zinc center also raised the carbonate content of PPC to over 99%, whereas the PPC from common rare earth ternary catalyst was about 96%. Unlike the highly regio‐regular structure PPC but with relatively low molecular weight recently reported in the literature, our high molecular weight regio‐regular PPC did show significant improvement in thermal and mechanical performances. PPC with H‐T linkages up to 83.2% showed glass transition temperature (T_g) of 43.3 °C, while T_g of PPC with H‐T linkages of 69.7% was only 36.1 °C. When H‐T connectivity was raised from 69.7 to 83.2%, the modulus of PPC showed a 78% increase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4451–4458, 2008     

Fixation of carbon dioxide into aliphatic polycarbonate,cobalt porphyrin catalyzed regio‐specific poly(propylene carbonate) with high molecular weight

Cobalt porphyrin complex (TPPCo^IIIX) (TPP = 5, 10, 15, 20‐Tetraphenyl‐ porphyrin; X = halide) in combination with ionic organic ammonium salt was used for the regio‐specific copolymerization of propylene oxide and carbon dioxide. A turnover frequency of 188 h^?1 was achieved after 5 h, and the byproduct propylene carbonate was successfully controlled to below 1%, where the obtained poly(propylene carbonate) (PPC) showed number average molecular weight (M_n) of 48 kg/mol, head‐to‐tail content of 93%, and carbonate linkage of over 99%. When the polymerization time was prolonged to 24 h, PPC with M_n over 115 kg/mol and head‐to‐tail linkage maintaining 90% was prepared, whose glass transition temperature reached 44.5 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5959–5967, 2008     

Biodegradable electrospun mat: Novel block copolymer of poly (p‐dioxanone‐co‐L‐lactide)‐block‐poly(ethylene glycol)

Ultrafine fibers of a laboratory‐synthesized new biodegradable poly(p‐dioxanone‐co‐L ‐lactide)‐block‐poly(ethylene glycol) copolymer were electrospun from solution and collected as a nonwoven mat. The structure and morphology of the electrospun membrane were investigated by scanning electron microscopy, differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and a mercury porosimeter. Solutions of the copolymer, ranging in the lactide fraction from 60 to 80 mol % in copolymer composition, were readily electrospun at room temperature from solutions up to 20 wt % in methylene chloride. We demonstrate the ability to control the fiber diameter of the copolymer as a function of solution concentration with dimethylformamide as a cosolvent. DSC and WAXD results showed the relatively poor crystallinity of the electrospun copolymer fiber. Electrospun copolymer membrane was applied for the hydrolytic degradation in phosphate buffer solution (pH = 7.5) at 37 °C. Preliminary results of the hydrolytic degradation demonstrated the degradation rate of the electrospun membrane was slower than that of the corresponding copolymers of cast film. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1955–1964, 2003