Crystallization and melting behavior of poly(ε‐caprolactone‐co‐δ‐valerolactone) and poly(ε‐caprolactone‐co‐L‐lactide) copolymers with novel chain microstructures

Nuclear magnetic resonance spectroscopy (NMR) characterization of the statistical copolymers of this study showed that the poly(ε‐caprolactone‐co‐L‐lactide)s, with ε‐caprolactone (ε‐CL) molar contents ranging from 70 to 94% and ε‐CL average sequence length (l_CL) between 2.20–9.52, and the poly(ε‐caprolactone‐co‐δ‐valerolactone)s, with 60 to 85% of ε‐CL and l_CL between 2.65–6.08, present semi‐alternating (R→2) and random (R～1) distribution of sequences, respectively. These syntheses were carried out with the aim of reducing the crystallinity of poly(ε‐caprolactone) (PCL), needed to provide mechanical strength to the material but also responsible for its slow degradation rate. However, this was not achieved in the case of the ε‐caprolactone‐co‐δ‐valerolactone (ε‐CL‐co‐δ‐VAL). Non‐isothermal cooling treatments at different rates and isothermal crystallizations (at 5, 10, 21 and 37°C) were conducted by differential scanning calorimetry (DSC), and demonstrated that ε‐CL copolymers containing δ‐valerolactone (δ‐VAL) exhibited a larger crystallization capability than those of L‐lactide (L‐LA) and also arranged into crystalline structures over shorter times. The crystallization enthalpies of the ε‐CL‐co‐δ‐VAL copolymers during the cooling treatments and their heat of fusion (ΔH_m) at the different isothermal temperatures were very large (i.e. ΔH_c > 53 Jg^?1) and in some cases, unrelated to the copolymer composition. In some compositions, such as the 60 : 40, Wide Angle X‐ray Scattering (WAXS) proved that that these two lactones undergo isomorphism and co‐crystallize in a single cell. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42534.     

Syntheses of cyclic poly(lactones) by zwitterionic ring opening polymerization catalyzed by N‐heterocyclic carbene

Synthesis of cyclic biopolymers from renewable monomers remains a big challenge because of lack of efficient catalysts. The organocatalyst of N‐heterocyclic carbene (NHC), (+)‐1‐methyl‐3‐menthoxymethyl imidazol‐2‐ylidene, is used to prepare cyclic polylactones including poly(ε‐caprolactone) (poly(ε‐CL)), poly(δ‐valearolactone) (poly(δ‐VL)), and poly(ε‐caprolactone‐co‐δ‐valearolactone) (poly(ε‐CL‐co‐δ‐VL)) via zwitterionic ring opening polymerization. The NHC catalyst is founded a highly efficient organic catalyst for the polymerization. The resulting cyclic polymers show a melting temperature (T_m) in a range of 20–60°C, which is dramatically lower than the T_m of cyclic poly(lactide) (T_m = 120–150°C). The resulting copolymer, cyclic poly(ε‐CL‐co‐δ‐VL) owns high molecular weight comparing with corresponding linear poly(ε‐CL‐co‐δ‐VL) produced by other catalysts. The synthesized cyclic homo and copolymers were characterized by ¹H‐, ¹³C‐NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry–thermogravimetric analysis and matrix‐assisted laser desorption ionization‐time of flight mass spectrometry. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of P(lLA‐co‐εCL) on the compatibility and crystallization behavior of PCL/PLLA blends

This article describes the compatibility of two semicrystalline polymers, poly(ε‐caprolactone) (PCL) and poly(l‐lactic acid) (PLLA). The compatibility of the PCL/PLLA blends was enhanced by the compatibilizing effect of the poly(l,l‐lactide‐co‐ε‐caprolactone) [P(lLA‐co‐εCL)]. A discussion details the effect of the concentration of the compatibilizing agent, the copolymer of l,l‐lactide and ε‐caprolactone of a 50/50 mol ratio [P(lLA‐co‐εCL)], on the compatibility and the crystallization behavior of the blends of PCL and PLLA. It was found that the addition of P(lLA‐co‐εCL) could suppress the crystallization of PLLA at its T_c and induced the concurrent crystallization of PLLA and PCL. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 226–231, 2000     

Synthesis and characterization of poly(L‐lactide‐co‐ϵ‐caprolactone)‐b‐poly(L‐lactide) biodegradable diblock copolyesters: Effect of the block lengths on their thermal properties

Poly(L ‐lactide‐co‐ε‐caprolactone)‐b‐poly(L ‐lactide) [P(LL‐co‐CL)‐b‐PLL] diblock copolyesters were synthesized in a two‐step process with 1‐dodecanol (DDC) and stannous octoate as the initiating system. In the first‐step reaction, a 50:50 mol % amorphous poly(L ‐lactide‐co‐ε‐caprolactone) [P(LL‐co‐CL)] copolyester was synthesized via the bulk copolymerization of L ‐lactide and ε‐caprolactone, which was followed by the polymerization of the PLL crystalline block at the end chain in the second‐step reaction. The yielded copolyesters were characterized with dilute‐solution viscometry, gel permeation chromatography, ¹H‐ and ¹³C‐NMR, and differential scanning calorimetry methods. The molecular weights of the P(LL‐co‐CL) copolyesters from the first‐step reaction were controlled by the DDC concentrations, whereas in the second‐step reaction, the molecular weights of the P(LL‐co‐CL)‐b‐PLL diblock copolyesters depended on the starting P(LL‐co‐CL) copolyester molecular weights and L ‐lactide/prepolymer molar ratios. The starting P(LL‐co‐CL) copolyester molecular weights and PLL block lengths seemed to be the main factors affecting specific thermal properties, including the melting temperature (T_m), heat of melting (ΔH_m), crystallizing temperature (T_c), and heat of crystallizing (ΔH_c), of the final P(LL‐co‐CL)‐b‐PLL diblock copolyester products. T_m, ΔH_m, T_c, and ΔH_c increased when the PLL block lengths increased. However, these thermal properties of the diblock copolyesters also decreased when the P(LL‐co‐CL) block lengths increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Biocompatibility evaluation of glycolide‐containing polyesters in contact with osteoblasts and fibroblasts

Biodegradable aliphatic polyesters have numerous biomedical applications and their capacity to degrade in biological fluids provides the significant advantage of their removal. Three glycolide‐containing aliphatic polyesters: a copolymer of glycolide and L ‐lactide (PGLA), a terpolymer of glycolide, L ‐lactide and ε‐caprolactone (PGLCap) and a copolymer of glycolide, and ε‐caprolactone (PGCap) were tested to evaluate their biocompatibility towards osteoblasts and fibroblasts. Each of the polymer units was previously reported to have acceptable biological properties and good biodegradability, and PGLA is already used for biomedical applications. Here we report that both PGLCap and PGCap affected cell adherence, and compromised cell viability as estimated by flow cytometric analyses of apoptotic and necrotic cells. The two polymers enhanced also production of numerous inflammation‐related factors: nitric oxide, matrix metalloproteinases (MMP‐2 and MMP‐9), and cytokines, including pro‐inflammatory TNF‐α, IL‐1β, IL‐6, and chemokines (IL‐8 or MCP‐1) attracting leukocytes. The effects of PGLCap and PGCap were similar despite the fact that they possess different characteristics: amorphous/smooth surface and semicristalline/rough surface, respectively. However, their common feature, distinctive from PGLA, is a presence of ε‐caprolactone units in their structure. This compound is considered to be acceptably biocompatible but our data suggest that its copolymerization with glycolide and L ‐lactide does not provide satisfactory biocompatibility towards osteoblasts and fibroblasts. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Shape‐memory bioresorbable terpolymer composite with antirestenotic drug

Shape‐memory polymers (SMPs) that combine shape‐memory, biodegradability, and controlled drug release properties are very promising for medical and pharmaceutical application. Moreover, incorporation of antirestenotic drug into SMP biodegradable stent seems to be an interesting solution because of possibility to combine the mechanical support that provides stent and also drug elution. The aim of our study was to analyze the effect of incorporation of sirolimus into poly(l ‐lactide‐co‐glycolide‐co‐trimethylene carbonate) on physicochemical and mechanical properties, degradation, and shape‐memory effect of the terpolymer. For this purpose, sirolimus was incorporated into the terpolymer by injection molding method. It has been demonstrated that drug‐free terpolymer after injection molding characterized insignificant changes in terpolymer composition. Degradation of materials during processing was not observed. Incorporation of drug molecules did not change shape‐memory properties of terpolymer. ¹H‐ and ¹³C‐NMR spectra of poly(lactide‐co‐glycolide‐co‐trimethylene carbonate) confirmed that changes during degradation were similar for terpolymer and terpolymer with sirolimus. Sustained and regular release of sirolimus was observed. The developed material presents potential for biomedical and pharmaceutical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41902.     

Design and synthesis of biodegradable copolyester poly(ε‐caprolactone‐co‐d,l‐lactide) with four pendent functional groups

A novel biodegradable copolyester poly(ε‐caprolactone‐co‐d ,l ‐lactide) with four pendent functional groups was designed and synthesized. The synthetic route includes the following three steps: (1) synthesis of OH‐terminated PCLA (PCLA‐OH) by the ring‐opening copolymerization of ε‐caprolactone and d ,l ‐lactide; (2) end‐group functionalization of PCLA‐OH through the esterification with lysine; and (3) synthesis of tetra‐amino‐terminated PCLA (PCLA‐NH₂) by removing the protecting groups. The composition, structure, and thermal property of these copolyesters were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and modulated differential scanning calorimetry. Results revealed that the molecular weight and glass transition temperature of PCLA‐NH₂ can be tailored by the careful selection of synthesis parameters. Moreover, polyester elastomers based on PCLA‐NH₂ were synthesized and characterized. These polyester elastomers are stabilized in their rubbery state in room temperature and exhibit tunable physiochemical and mechanical properties. POLYM. ENG. SCI., 54:2170–2176, 2014. © 2013 Society of Plastics Engineers     

Synthesis,characterization and (electro)chemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone)

Triphenylamine‐based oligomers and polymers with linear, hyperbranched, star‐shaped or dendrimer architectures have been synthesized and studied due to their interesting electro‐optical properties. In many cases insoluble materials are obtained. In this study, we report the synthesis of grafted polytriphenylamine by chemical and electrochemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone). Functionalized ε‐caprolactone oligomers were obtained by ring‐opening polymerization of ε‐caprolactone initiated by 4‐hydroxymethyltriphenylamine/stannous octanoate (tin 2‐ethylhexanoate). The ring‐opening polymerization of ε‐caprolactone using 4‐hydroxymethyltriphenylamine/stannous octanoate as initiating system provided ε‐caprolactone oligomers, with well‐defined molecular weights, containing a triphenylamine terminal group. Chemical and electrochemical coupling oxidation of the triphenylamine ends allowed the formulation of polyarylamines with ε‐caprolactone oligomers as grafts. Graft copolymers with an aryleneamine backbone and short poly(ε‐caprolactone) grafts were obtained by (electro)chemical oxidation of oligomers containing triphenylamine terminal groups. Copyright © 2009 Society of Chemical Industry     

Effects of plasma treatment on biocompatibility of poly[(L‐lactide)‐co‐(ϵ‐caprolactone)] and poly[(L‐lactide)‐co‐glycolide] electrospun nanofibrous membranes

Poly[(l ‐lactide)‐co ‐(? ‐caprolactone)] (PLCL) and poly[(l ‐lactide)‐co ‐glycolide] (PLGA) copolymers are widely used in neural guide tissue regeneration. In this research, the surface modification of their hydrophilicity was achieved using plasma treatment. Attachment and proliferation of olfactory ensheathing cells on treated electrospun membranes increased by 26 and 32%, respectively, compared to the untreated PLCL and PLGA counterparts. Cells cultivated on both the PLCL and PLGA membranes showed high viability (>95%) and healthy morphologies with no evidence of cytotoxic effects. Cells grown on treated electrospun fibres displayed significant increases in mitochondrial activity and reductions in membrane leakage when compared to untreated samples. The results suggested that plasma treatment of the surface of the polymers enhanced both cell viability and growth without incurring any cytotoxic effects. © 2017 Society of Chemical Industry     

Temperature‐responsiveness and sustained delivery properties of macroporous PEG‐co‐PNIPAAm‐co‐PCL hydrogels

A series of novel thermosensitive macroporous poly (ethylene glycol) (PEG)‐co‐poly(N‐isopropylacrylamide) (PNIPAAm)‐co‐poly (ε‐caprolactone) (PCL) hydrogels were synthesized via in situ free radical polymerization. Poly(ethylene glycol diacrylate) (PEGDAc) and poly(ε‐caprolactone diacrylate) (PCLDAc) were prepared as macrocrosslinkers. All compounds were investigated by Nuclear Magnetic Resonance (NMR) and Fourier transform‐infrared spectroscopy (FT‐IR). Differential Scanning Calorimetry (DSC) results showed the lower critical solution temperatures (LCSTs) of the gels were at around 31°C. The macroporous gels not only had considerable swelling ratios, but also exhibited rapid swelling kinetics and response sensitivity. Above mentioned hydrogels showed a remarkable oscillatory swelling–deswelling transition, making them have potential application in long‐term drug delivery. POLYM. ENG. SCI., 55:223–230, 2015. © 2014 Society of Plastics Engineers     

Preparation and drug release behaviors of 5‐fluorouracil loaded poly(glycolide‐co‐lactide‐co‐caprolactone) nanoparticles

5‐Fluorouracil (5‐Fu) loaded poly(glycolide‐co‐lactide‐co‐caprolactone) (PGLC) nanoparticles were prepared by modified spontaneous emulsification solvent diffusion method (modified‐SESD method) and characterized by dynamic light scattering, scanning electron microscopy and ¹H NMR determination. It was found that the obtained nanoparticles showed near spherical shape and was controllable with the radius range of 30–100 nm. Compared with the nanoparticles prepared by polylactide and poly (lactide‐co‐glycolide) (PLGA) under the similar preparation condition, yield of PGLC nanoparticles was the highest, which reached to about 100%. On the other hand, drug entrapment efficiency of PGLC nanoparticles was also higher than that of PLGA and PLLA nanoparticles. 5‐Fu release behavior of PGLC nanoparticles in vitro showed that 5‐Fu release of PGLC nanoparticles showed a near zero‐order release profile, and 5‐Fu release rate of PGLC nanoparticles was faster than that of PLLA and PLGA nanoparticles. According to degradation behavior of PGLC nanoparticles, it could be proposed that the kinetic of degradation controlled release played an important role in the release process of PGLC nanoparticles. It revealed that the PGLC nanoparticles could be a promising drug carrier. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis,characterization and biocompatibility of novel biodegradable poly[((R)‐3‐hydroxybutyrate)‐block‐(D,L‐lactide)‐block‐(ε‐caprolactone)] triblock copolymers

BACKGROUND: Biodegradable block copolymers have attracted particular attention in both fundamental and applied research because of their unique chain architecture, biodegradability and biocompatibility. Hence, biodegradable poly[((R )‐3 ‐hydroxybutyrate)‐block‐(D ,L ‐lactide)‐block‐(ε‐caprolactone)] (PHB‐PLA‐PCL) triblock copolymers were synthesized, characterized and evaluated for their biocompatibility. RESULTS: The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis showed that the novel triblock copolymers were successfully synthesized. Differential scanning calorimetry and wide‐angle X‐ray diffraction showed that the crystallinity of PHB in the copolymers decreased compared with methyl‐PHB (LMPHB) oligomer precursor. Blood compatibility experiments showed that the blood coagulation time became longer accompanied by a reduced number of platelets adhering to films of the copolymers with decreasing PHB content in the triblocks. Murine osteoblast MC3T3‐E1 cells cultured on the triblock copolymer films spread and proliferated significantly better compared with their growth on homopolymers of PHB, PLA and PCL, respectively. CONCLUSION: For the first time, PHB‐PLA‐PCL triblock copolymers were synthesized using low molecular weight LMPHB oligomer as the macroinitiator through ring‐opening polymerization with D ,L ‐lactide and ε‐caprolactone. The triblock copolymers exhibited flexible properties with good biocompatibility; they could be developed into promising biomedical materials for in vivo applications. Copyright © 2008 Society of Chemical Industry     

Synthesis of poly(vinyl alcohol)‐graft‐poly(ε‐caprolactone) and poly(vinyl alcohol)‐graft‐poly(lactide) in melt with magnesium hydride as catalyst

Grafting of poly(ε‐caprolactone) (PCL) and poly(lactide) (PLA) chains on poly(vinyl alcohol) backbone (PVA degree of hydrolysis 99%) was investigated using MgH₂ environmental catalyst and melt‐grown ring‐opening polymerization (ROP) of ε‐caprolactone (CL) and L ‐lactide (LA), that avoiding undesirable toxic catalyst and solvent. The ability of MgH₂ as catalyst as well as yield of reaction were discussed according to various PVA/CL/MgH₂ and PVA/LA/MgH₂ ratio. PVA‐g‐PCL and PVA‐g‐PLA were characterized by ¹H‐ and ¹³C‐NMR, DSC, SEC, IR. For graft copolymers easily soluble in tetrahydrofuran (THF) or chloroform, wettability and surface energy of cast film varied in relation with the length and number of hydrophobic chains. Aqueous solution of micelle‐like particles was realized by dissolution in THF then addition of water. Critical micelle concentration (CMC) decreased with hydrophobic chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers by combined ring‐opening polymerization and cross‐coupling processes

2,5‐Dibromo‐1,4‐(dihydroxymethyl)benzene was used as initiator in ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate (Sn(Oct)₂) catalyst. The resulting poly(ε‐caprolactone) (PCL) macromonomer, with a central 2,5‐dibromo‐1,4‐diphenylene group, was used in combination with 1,4‐dibromo‐2,5‐dimethylbenzene for a Suzuki coupling in the presence of Pd(PPh₃)₄ as catalyst or using the system NiCl₂/bpy/PPh₃/Zn for a Yamamoto‐type polymerization. The poly(p‐phenylenes) (PPP) obtained, with PCL side chains, have solubility properties similar to those of the starting macromonomer, ie soluble in common organic solvents at room temperature. The new polymers were characterized by ¹H and ¹³C NMR and UV spectroscopy and also by GPC measurements. The thermal behaviour of the precursor PCL macromonomer and the final poly(p‐phenylene)‐graft‐poly(ε‐caprolactone) copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry analyses and compared. Copyright © 2004 Society of Chemical Industry     

Degradation of PLA,PLGA homo‐ and copolymers in the presence of serum albumin: a spectroscopic investigation

Poly(D,L ‐lactide‐co‐glycolide) samples with different glycolide contents, ie 85:15, 75:25 and 50:50 mole ratios of lactide to glycolide, and poly(L ‐lactide) were obtained from a commercial source. Polymer films of 15 µm thickness were prepared by a solvent‐casting method. Degradation studies were conducted at 37 °C in pH 7.4 phosphate buffered saline and in bovine serum albumin solution. The degradation behaviour of the films was followed by UV and FTIR spectrophotometry and viscometric and gravimetric measurements. Spectroscopic investigations showed that during the first month of degradation, both the chain length and the chain chemical structure changed, especially in the presence of bovine serum albumin. The short chains are attributed to the formation of new ester groups; however, the end‐groups may be aldehyde‐ or ketone‐like structures. While the intrinsic viscosities of all polymers decreased continuously after being exposed to the degradation media, insignificant mass loss occurred during the experimental investigation. © 2000 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     

Synthesis,characterization, and cytotoxicity of star‐shaped polyester‐based elastomers as controlled release systems for proteins

With the growing number of therapeutic proteins on the market, effective delivery systems are receiving particular attention. In this study, biodegradable elastomers, intended for protein drug delivery and based on methacrylic tripoly(ε‐caprolactone‐co‐d ,l ‐lactide) cyclic ester with different ratios of ?‐caprolactone to d ,l ‐lactide and methacrylic bipoly[?‐caprolactone‐b‐poly(ethylene glycol)‐b‐?‐caprolactone], were synthesized and characterized. The degradation behavior, bovine serum albumin (BSA)‐releasing kinetics, and cytotoxicity of the elastomers in vitro were investigated. The elastomers were degraded by the hydrolysis of the ester bond; this resulted in pH changes, which further affected the degradation rate. The BSA‐releasing behavior was strongly dependent on the diffusion mechanism. In the diffusion‐controlled period, nearly sustained and stable BSA release was achieved. Furthermore, the elastomers displayed good biocompatibility, as demonstrated by a 3‐(4,5‐dimethyl thiazol‐2‐yl)?2,5‐diphenyl tetrazolium bromide assay and inflammation–induction experiments, and are considered promising candidates for the controllable delivery of protein drugs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43393.     

Preparation of poly(ε‐caprolactone)/poly(ε‐caprolactone‐co‐lactide) (PCL/PLCL) blend filament by melt spinning

Poly(ε‐caprolactone)/poly(ε‐caprolactone‐co‐lactide) (PCL/PLCL) blend filaments with various ratios of PCL and PLCL were prepared by melt spinning. The effect of PLCL content on the physical properties of the blended filament was investigated. The melt spinning of the blend was carried out and the as spun filament was subsequently subjected to drawing and heat setting process. The addition of PLCL caused significant changes in the mechanical properties of the filaments. Crystallinity of blend decreased with the addition of PLCL as observed by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) revealed that the fracture surface becomes rougher at higher PLCL content. It may be proposed that PCL and PLCL show limited interaction within the blend matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Environmental degradation and biofouling of ‘green’ plastics including short and medium chain length polyhydroxyalkanoates

Biopolymers derived from natural resources are potential alternatives to recalcitrant synthetic plastics; however, studies investigating the degradability of these biopolymers in natural environments are relatively few. This study compares the environmental degradation of polymers described as ‘green plastics’ in garden soil in terms of weight loss, topographical changes and biofilm attachment. Poly(3‐hydroxybutyrate) (PHB) and poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyvalerate)] (P(HB‐co‐8HV)), (copolymer containing 8 mol% HV) films degraded rapidly, losing 50% of their initial weight in 50 days. In contrast, after burial for 380 days, the medium chain length polyhydroxyoctanoate (PHO) lost 60% of its weight, poly(D ,L ‐lactide) (PDLL) 18% and poly[(D ,L ‐lactide)‐co‐glycolide] (PDLLG) 35%. Polystyrene (PS) and ethyl cellulose (EC) showed no significant degradation. Both weight loss and biofouling occurred in the following sequence: P(HB‐co‐8HV) = PHB > PHO > PDLLG > PDLL > PS = EC. The surface rugosity and surface areas of PHB and P(HB‐co‐8HV) increased three‐ and twofold, respectively, during degradation, indicating surface erosion. The surface rugosity of PHO increased twofold and the surface area increased by 25%. This in situ study demonstrates a quantifiable relationship between biofilm attachment, surface rugosity and polymer degradation. PHB and P(HB‐co‐8HV) showed greater biofouling and increased surface rugosity, and degraded significantly faster than the other polymers studied. Copyright © 2009 Society of Chemical Industry     

AB‐ and ABC‐type di‐ and triblock copolymers of poly[styrene‐block‐(ε‐caprolactone)] and poly[styrene‐block‐(ε‐caprolactone)‐block‐lactide]: synthesis,characterization and thermal studies

Polystyrene terminated with benzyl alcohol units was employed as a macroinitiator for ring‐opening polymerization of ε‐caprolactone and L ‐lactide to yield AB‐ and ABC‐type block copolymers. Even though there are many reports on the diblock copolymers of poly(styrene‐block‐lactide) and poly(styrene‐block‐lactone), this is the first report on the poly(styrene‐block‐lactone‐block‐lactide) triblock copolymer consisting of two semicrystalline and degradable segments. The triblock copolymers exhibited twin melting behavior in differential scanning calorimetry (DSC) analysis with thermal transitions corresponding to each of the lactone and lactide blocks. The block derived from ε‐caprolactone also showed crystallization transitions upon cooling from the melt. In the DSC analysis, one of the triblock copolymers showed an exothermic transition well above the melting temperature upon cooling. Thermogravimetric analysis of these block copolymers showed a two‐step degradation curve for the diblock copolymer and a three‐step degradation for the triblock copolymer with each of the degradation steps associated with each segment of the block copolymers. The present study shows that it is possible to make pure triblock copolymers with two semicrystalline segments which also consist of degradable blocks. Copyright © 2009 Society of Chemical Industry