Random copolymerization of 2,2‐dimethyltri methylene carbonate and ε‐caprolactone using a rare‐earth tris(4‐tert‐butylphenolate)s as a single‐component initiator

Highly random copolymers of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (CL) were synthesized by single component rare‐earth tris(4‐tert‐butylphenolate)s [Ln(OTBP)₃] for the first time. The influences of reaction conditions on the copolymerization initiated by La(OTBP)₃ have been examined in detail. The monomer reactivity ratios of DTC and CL determined by the Fineman–Ross method are 4.0 for r_DTC and 0.27 for r_CL. The microstructure of the copolymer was determined by the analyses of the diads DTC–DTC, DTC–CL, CL–DTC and CL–CL of the ¹H NMR spectra. The high degree of randomness of the chain structure was further confirmed by the ¹³C NMR spectra and differential scanning calorimetry. The thermal properties of the copolymers as a function of composition are reported. The mechanism investigated by ¹H NMR data indicates that the rare‐earth tris(4‐tert‐butylphenolate)s initiate the ring‐opening copolymerization of DTC and CL with acyl‐oxygen bond cleavages of the monomers. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of α‐amino acid‐containing polyester: poly[(ε‐caprolactone)‐co‐(serine lactone)]

Novel polyesters, poly[(ε‐caprolactone)‐co‐(N‐trityl‐L ‐serine‐β‐lactone)]s, were prepared by copolymerizing ε‐caprolactone (CL) with N‐trityl‐L ‐serine‐β‐lactone (TSL) using ZnEt₂ as the catalyst. The number‐average molecular weights were determined which ranged from 2.7 × 10⁴ to 4.9 × 10⁴ Da with dispersity values ranging from 1.6 to 1.8. The structures of the copolymers were investigated by means of ¹H NMR, ¹³C NMR and infrared spectroscopies, thermogravimetric analysis and differential scanning calorimetry. The results indicated that CL and TSL monomer units were randomly distributed within the copolymer backbone structures and the ratios of TSL to CL in the copolymers were close to those in the feeds. After removal of the trityl group under mild condition, a new polyester with side amino groups provided by serine units was obtained. L929 cell culturing test indicated good biocompatibility of the polyester with or without protective groups. © 2012 Society of Chemical Industry     

One‐step synthesis of star‐block copolymers via simultaneous free radical polymerization of styrene and ring opening polymerization of ε‐caprolacton using tetrafunctional iniferter

Star‐block copolymers comprised of poly(styrene) (S) core and four poly(ε‐caprolacton) (ε‐CL) arms were synthesized by the combination of free radical polymerization (FRP) of S and ring opening polymerization (ROP) of ε‐CL in one‐step in the presence of tetrafunctional ineferter. The block copolymers were characterized by ¹H‐NMR and FTIR spectroscopy, gel permeation chromatography (GPC), and fractional precipitation method. ¹H ‐NMR and FTIR spectroscopy and GPC studies of the obtained polymers indicate that star‐block copolymers easily formed as result of combination FRP and ROP in one‐step. The γ values (solvent/precipitant volume ratio) were observed between 1.04–2.72 (mL/mL) from fractional measurements. The results show that when the initial S feed increased, the molecular weights of the star‐block copolymers also increased and the polydispersities of the polymers decreased. M_w/M_n values of the products were measured between 1.4 and 2.86 from GPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and biological activity of medium range molecular weight polymers containing exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid

A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid (ETCA), was prepared by reaction of maleimidocaproic acid and furan. The homopolymer of ETCA and its copolymers with acrylic acid (AA) or with vinyl acetate (VAc) were obtained by photopolymerizations using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETCA and its polymers were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The apparent average molecular weights and polydispersity indices determined by gel permeation chromatography (GPC) were as follows: M_n = 9600 g mol^?1, M_w = 9800 g mol^?1, M_w/M_n = 1.1 for poly(ETCA); M_n = 14 300 g mol^?1, M_w = 16 200 g mol^?1, M_w/M_n = 1.2 for poly(ETCA‐co‐AA); M_n = 17 900 g mol^?1, M_w = 18 300 g mol^?1, M_w/M_n = 1.1 for poly(ETCA‐co‐VAc). The in vitro cytotoxicity of the synthesized compounds against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines decreased in the following order: 5‐fluorouracil (5‐FU) ≥ ETCA > polymers. The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐FU at all doses tested. © 2001 Society of Chemical Industry     

Synthesis and characterization of a random terpolymer of L‐lactide, ϵ‐caprolactone and glycolide

A random terpolymer of L ‐lactide (LL), ?‐caprolactone (CL) and glycolide (G) has been synthesized in bulk at 130 °C using stannous octoate as the coordination–insertion initiator. The terpolymer, poly(LL‐ran‐CL‐ran‐G), has been characterized by a combination of analytical techniques: GPC, ¹H NMR, ¹³C NMR, DSC and TG. Molecular weight characterization by GPC shows a unimodal molecular weight distribution with values of M _n = 1.01 × 10⁵ g mol^?1 and M _w / M _n = 2.17. Compositional and microstructural analysis by ¹H NMR and ¹³C NMR, respectively, reveal a terpolymer composition of LL:CL:G = 74:15:11 (mol%) with a chain microstructure consistent with random monomer sequencing. This latter view is supported by the terpolymer temperature transitions (T_g and T_m) from DSC and the thermal decomposition profile from TG. The results and, in particular, the conclusion that it is a random rather than a statistical terpolymer are discussed in the light of current theories regarding the mechanism of this type of polymerization. © 2001 Society of Chemical Industry     

Non‐catalyst synthesis and in vitro drug release property of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) copolymers

A series of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) (PDTC‐b‐mPEG) copolymers were synthesized by the ring‐opening polymerization of 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DTC) in bulk, using methoxy poly(ethylene glycol) (mPEG) as initiator without adding any catalysts. The resulting copolymers were characterized by Fourier transform infrared spectra, ¹H NMR and gel permeation chromatography. The influences of some factors such as the DTC/mPEG molar feed ratio, reaction time and reaction temperature on the copolymerization were investigated. The experimental results showed that mPEG could effectively initiate the ring‐opening polymerization of DTC in the absence of catalyst, and that the copolymerization conditions had a significant effect on the molecular weight of PDTC‐b‐mPEG copolymer. In vitro drug release study demonstrated that the amount of indomethacin released from PDTC‐b‐mPEG copolymer decreased with increase in the DTC content in the copolymer. © 2013 Society of Chemical Industry     

Polyethylene‐block‐poly(ε‐caprolactone) diblock copolymers: synthesis and compatibility

A strategy is introduced for the synthesis of polyethylene‐block‐poly(ε‐caprolactone) block copolymers by a combination of coordination polymerization and ring‐opening polymerization. First, end‐hydroxylated polyethylene (PE‐OH) was prepared with a one‐step process through ethylene/3‐buten‐1‐ol copolymerization catalyzed by a vanadium(III) complex bearing a bidentate [N,O] ligand ([PhN?C(CH₃)CHC(Ph)O]VCl₂(THF)₂). The PE‐OH was then used as macroinitiator for ring‐opening polymerization of ε‐caprolactone, leading to the desired nonpolar/polar diblock copolymers. The block structure was confirmed by spectral analysis using ¹H NMR, gel permeation chromatography and differential scanning calorimetry. The unusual topologies of the model copolymers will establish a fundamental understanding for structure–property correlations, e.g. compatibilization, of polymer blends and surface and interface modification of other polymers. © 2014 Society of Chemical Industry     

Synthesis and biological activity of phthalimide‐based polymers containing 5‐fluorouracil

The attachment of anticancer agents to polymers is a promising approach towards reducing the toxic side‐effects and retaining the potent antitumour activity of these agents. A new tetrahydrophthalimido monomer containing 5‐fluorouracil (ETPFU) and its homopolymer and copolymers with acrylic acid (AA) and with vinyl acetate (VAc) have been synthesized and spectroscopically characterized. The ETPFU contents in poly(ETPFU‐co‐AA) and poly(ETPFU‐co‐VAc) obtained by elemental analysis were 21 mol% and 20 mol%, respectively. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: M_n = 8900 g mol^?1, M_w = 13 300 g mol^?1, M_w/M_n = 1.5 for poly(ETPFU); M_n = 13 500 g mol^?1, M_w = 16 600 g mol^?1, M_w/M_n = 1.2 for poly(ETPFU‐co‐AA); M_n = 8300 g mol^?1, M_w = 11 600 g mol^?1, M_w/M_n = 1.4 poly(ETPFU‐co‐VAc). The in vitro cytotoxicity of the compounds against FM3A and U937 cancer cell lines increased in the following order: ETPFU > 5‐FU > poly(ETPFU) > poly(ETPFU‐co‐AA) > poly(ETPFU‐co‐VAc). The in vivo antitumour activities of all the polymers in Balb/C mice bearing the sarcoma 180 tumour cell line were greater than those of 5‐FU and monomer at the highest dose (800 mg kg^?1). © 2002 Society of Chemical Industry     

Synthesis of PMMA‐PTHF‐PMMA and PMMA‐PTHF‐PST linear and star block copolymers

Combination of cationic, redox free radical, and thermal free radical polymerizations was performed to obtain linear and star polytetramethylene oxide (poly‐THF)‐polymethyl methacrylate (PMMA)/polystyrene (PSt) multiblock copolymers. Cationic polymerization of THF was initiated by the mixture of AgSbF₆ and bis(4,4′ bromo‐methyl benzoyl) peroxide (BBP) or bis (3,5,3′,5′ dibromomethyl benzoyl) peroxide (BDBP) at 20°C to obtain linear and star poly‐THF initiators with M_w varying from 7,500 to 59,000 Da. Poly‐THF samples with hydroxyl ends were used in the methyl methacrylate (MMA) polymerization in the presence of Ce(IV) salt at 40°C to obtain poly(THF‐b‐MMA) block copolymers containing the peroxide group in the middle. Poly(MMA‐b‐THF) linear and star block copolymers having the peroxide group in the chain were used in the polymerization of methyl methacrylate (MMA) and styrene (St) at 80°C to obtain PMMA‐b‐PTHF‐b‐PMMA and PMMA‐b‐PTHF‐b‐PSt linear and star multiblock copolymers. Polymers obtained were characterizated by GPC, FT‐IR, DSC, TGA, ¹H‐NMR, and ¹³C‐NMR techniques and the fractional precipitation method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 219–226, 2004     

Preparation of poly(styrene‐b‐2‐hydroxyethyl acrylate) block copolymer using reverse iodine transfer polymerization

Reverse iodine transfer polymerizations (RITP) of 2‐h‐ydroxyethyl acrylate (HEA) were performed in N,N‐dimethylformamide at 75°C using AIBN as initiator. Poly(2‐hydroxyethyl acrylate) (PHEA) with M_n = 3300 g mol^?1 and M_w/M_n <1.5 were obtained. Homopolymerization of styrene in RITP was also carried out under similar conditions using toluene as solvent. The resulting iodo‐polystyrene (PS‐I) with (M_{n, SEC} = 607 g mol^?1, polydispersity index (PDI) = 1.31) was used as a macroinitiator for the synthesis of amphiphilic block copolymers based on HEA with controlled well‐defined structure. Poly(styrene‐b‐2‐hydroxyethyl acrylate) (PS‐b‐PHEA) with M_n = 13,000 g mol^?1 and polydispersity index (M_w/M_n) = 1.4 was obtained, copolymer composition was characterized using ¹H‐NMR and FTIR, whereas SEC and gradient HPLC were used to confirm the formation of block copolymer and the living character of polymer chains. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Copolymerization of phenylisocyanate and ϵ‐caprolactone with rare earth chloride systems

A copolymer of phenylisocyanate (PhNCO) and ε‐caprolactone (CL) was synthesized by the rare earth chloride systems lanthanide chloride isopropanol complex (LnCl₃·3iPrOH) and propylene epoxide (PO). Polymerization conditions were investigated, such as lanthanides, reaction temperature, monomer feed ratio, La/PO molar ratio, and aging time of catalyst. The optimum conditions were: LaCl₃ preferable, [PhNCO]/[CL] in feed = 1 : 1 (molar ratio), 30°C, [monomer]/[La] = 200, [PO]/[La] = 20, aging 15 min, polymerization in bulk for 6 h. Under such conditions the copolymer obtained had 39 mol % PhNCO with a 78.2% yield, M_n = 20.3 × 10³, and M_w/M_n = 1.60. The copolymers were characterized by GPC, TGA, ¹H‐NMR, and ¹³C‐NMR, and the results showed that the copolymer obtained had a blocky structure with long sequences of each monomer unit. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2135–2140, 2007     

Synthesis and properties of random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate catalyzed by lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)

Random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(DBMP)₃; Ln = La, Nd, Sm, or Dy] as catalysts, among which La(DBMP)₃ showed the highest activity. Poly(2,2‐dimethyltrimethylene carbonate‐co‐ethylene carbonate)s [poly(DTC‐co‐EC)]s with high molecular weights were prepared at room temperature and characterized with ¹H‐NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC‐co‐EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X‐ray diffraction. The crystallinity and melting temperatures of the poly(DTC‐co‐EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass‐transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of semi‐crystalline poly(ε‐caprolactone) and non‐crystalline polylactide blocks on the thermal properties of polydimethylsiloxane‐based block copolymers

Poly(A)‐block‐poly(B), poly(A)‐block‐poly(B)‐block‐poly(A) and B(A)₂ block copolymers were prepared through coordinated anionic ring‐opening polymerization of ε‐caprolactone (CL) and lactic acid (LA) using hydroxy‐terminated polydimethylsiloxane (PDMS) as initiator. A wide range of well‐defined combinations of PDMS‐block‐PCL and PDMS‐block‐PLA diblock copolymers, PCL‐block‐PDMS‐block‐PCL and PLA‐block‐PDMS‐block‐PLA triblock copolymers and star‐PDMS(PCL)₂ copolymers were thus obtained. The number‐average molar masses and the structure of the synthesized block copolymers were identified using various analytical techniques. The thermal properties of these copolymers were established using differential scanning calorimetry. Considering PDMS‐block‐PCL copolymers, the results demonstrate the complex effect of polymer architecture and PCL block length on the ability of the PDMS block to crystallize or not. In the case of diblock copolymers, crystallization of PCL blocks originated from stacking of adjacent chains inducing the extension of the PDMS block that can easily crystallize. In the case of star copolymers, the same tendency as in triblock copolymers is observed, showing a limited crystallization of PDMS when the length of the PCL block increases. In the case of PDMS‐block‐PLA copolymers, melting and crystallization transitions of the PLA block are never observed. Considering the diblock copolymers, PDMS sequences have the ability to crystallize. © 2019 Society of Chemical Industry     

Synthesis and Characterization of Biodegradable Poly(ε‐caprolactone)‐Polyglycolide‐Poly(ethylene glycol) Monomethyl Ether Random Copolymer

Summary: Poly(ε‐caprolactone)‐polyglycolide‐poly(ethylene glycol) monomethyl ether random copolymers were synthesized from ε‐caprolactone (ε‐CL), glycolide (GA) and poly(ethylene glycol) monomethyl ether (MPEG) using stannous octoate as catalyst at 160 °C by bulk polymerization. The copolymers with different composition were synthesized by adjusting the weight ration of reaction mixture. The resultant copolymer with a weight ratio (10:15:75) of MPEG2000, GA, and CL was characterized by IR, ¹H NMR, GPC and DSC. The new biodegradable copolymer has potential for medical applications since it is combined with properties of PCL, PGA and MPEG.

     

Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene) graft copolymers by a combination of cationic and photopolymerization methods

Poly(epichlorohydrin‐g‐styrene) and poly (epichlorohydrin‐g‐methyl methacrylate) graft copolymers were synthesized by a combination of cationic and photoinitiated free‐radical polymerization. For this purpose, first, epichlorohydrin was polymerized with tetrafluoroboric acid (HBF₄) via a cationic ring‐opening mechanism, and, then, polyepichlorohydrin (PECH) was reacted ethyl‐hydroxymethyl dithio sodium carbamate to obtain a macrophotoinitiator. PECH, possessing photolabile thiuram disulfide groups, was used in the photoinduced polymerization of styrene or methyl methacrylate to yield the graft copolymers. The graft copolymers were characterized by ¹H‐NMR spectroscopy, differential scanning calorimetry, and gel permeation chromatography. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate) triblock copolymers

Novel, monodispersed, and well‐defined ABA triblock copolymers [poly(dimethylamino ethyl methacrylate)–poly(ethylene oxide)–poly(dimethylamino ethyl methacrylate)] were synthesized by oxyanionic polymerization with potassium tert‐butanoxide as the initiator. Gel permeation chromatography and ¹H‐NMR analysis showed that the obtained products were the desired copolymers with molecular weights close to calculated values. Because the poly(dimethylamino ethyl methacrylate) block was pH‐ and temperature‐sensitive, the aqueous solution behavior of the polymers was investigated with ¹H‐NMR and dynamic light scattering techniques at different pH values and at different temperatures. The micelle morphology was determined with transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate) triblock copolymer by atom transfer radical polymerization

The synthesis of triblock copolymer poly(octadecyl acrylate‐b‐styrene‐b‐octadecyl acrylate), using atom transfer radical polymerization (ATRP), is reported. The copolymers were prepared in two steps. First, polystyrene was synthesized by ATRP using α,α′‐dichloro‐p‐xylene/CuBr/bpy as the initiating system; Second, polystyrene was further used as macroinitiator for the ATRP of octadecyl acrylate to prepare ABA triblock copolymers in the presence of FeCl₂·4H₂O/PPh₃ in toluene. Polymers with controlled molecular weight (M_n = 17,000–23,400) and low polydispersity index value (1.33–1.44) were obtained. The relationship between molecular weight versus conversion showed a straight line. The effect of reaction temperature on polymerization was also investigated, showing a faster polymerization rate under higher temperature. The copolymers were characterized by FTIR, ¹H‐NMR, DSC, and GPC and the crystallization behavior of the copolymers was also studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1539–1545, 2004     

Synthesis and characterization of poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented block copolymers

Poly(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol) segmented random copolymers, with poly(butylene succinate) (PBS) molar fraction (M_PBS) varying from 10 to 60 %, were synthesized through a melt polycondensation process and characterized by means of GPC, NMR, DSC and mechanical testing. The number‐average relative molecular mass of the copolymers was higher than 4 × 10⁴ g mol^?1 with polydispersity below 1.9. Sequence distribution analysis on the two types of hard segments by means of ¹H NMR revealed that the number‐average sequence length of PBT decreased from 2.80 to 1.23, while that of PBS increased from 1.27 to 4.76 with increasing M_PBS. The random distribution of hard segments was also justified because of the degree of randomness around 1.0. Micro‐phase separation structure was verified for the appearance of two glass transition temperatures and two melting points, respectively, in DSC thermograms of most samples. The crystallinity of hard segments changed with the crystallizability controlled by the average sequence length and reached the minimum value at an M_PBS of about 50–60 mol%. The results can also be ascribed to the co‐crystallization between two structurally analogous hard segments. Mechanical testing results demonstrated that incorporating a certain amount of PBS moieties (less than 30 mol%), at the expense of a minute depression of the elastic modulus, that higher relative elongation and more flexibility of polymer chain could be expected. Maximum equilibrium water absorption and faster degradation rates were observed on samples with higher M_PBS values and lower crystallinity of hard segments were better hydrophilicity of the polymer chain, through in vitro degradation experiments. Copyright © 2003 Society of Chemical Industry     

High yield synthesis of diverse well‐defined end‐functionalized polymers by combination of anionic polymerization and “click” chemistry

Well‐defined poly(methyl methacrylate) (M_n = 3630 g mol^?1, PDI = 1.06) with a primary benzylic bromide prepared using anionic polymerization was successfully transformed into diverse end‐functionalities (ω‐carboxyl, ω‐hydroxy, ω‐methyl‐vinyl, ω‐trimethylsilane, and ω‐glycidyl‐ether) via “click” reaction. The bromine end‐terminated poly(methyl methacrylate) was first substituted by an azide function and sequentially was reacted with various functional alkynes (propiolic acid, propargyl alcohol, 2‐methyl‐1‐buten‐3‐yne, propargyl trimethylsilane, and propargyl glycidylether). In all the cases, ¹H‐NMR, ¹³C NMR, FT‐IR, and GPC measurements show qualitative and quantitative transformation of the chain‐end poly(methyl methacrylate) into the desired functionalities with high conversion (above 99%). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of high‐molecular‐weight poly(L‐lactic acid)‐based polymers through direct condensation polymerization in bulk state

Poly(L ‐lactic acid‐co‐succinic acid‐co‐1,4‐butanediol) (PLASB) was synthesized by a direct condensation copolymerization of L ‐lactic acid, succinic acid (SA), and 1,4‐butanediol (BD) in bulk state using titanium(IV) butoxide (TNBT) as a catalyst. Weight average molecular weight (M_w) of PLASB increased from 3.5 × 10⁴ to 2.1 × 10⁵ as the content of SA and BD went up from 0.01 to 0.5 mol/100 mol of L ‐lactic acid (LA). PLASB having M_w in the range from 1.8 × 10⁵ to 2.1 × 10⁵ showed tensile properties comparable to those of commercially available poly(L ‐lactic acid) (PLLA). In sharp contrast, homopolymerization of LA in bulk state produced PLLA with M_w as low as 4.1 × 10⁴, and it was too brittle to prepare specimens for the tensile tests. M_w of PLASB synthesized by using titanium(IV)‐2‐ethyl(hexoxide), indium acetate, indium hydroxide, antimony acetate, antimony trioxide, dibutyl tin oxide, and stannous‐2‐ethyl 1‐hexanoate was compared with that of PLASB obtained by TNBT. Ethylene glycol oligomers with different chain length were added to LA/SA in place of BD to investigate effect of chain length of ethylene glycol oligomers on the M_w of the resulting copolymers. Biodegradability of PLASB was analyzed by using the modified Sturm test. Toxicity of PLASB was evaluated by counting viable cell number of mouse fibroblast cells that had been in contact with PLASB discs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 466–472, 2006