Pendant Hydroxyl Research Articles

Facile synthesis of thiol-terminated poly(styrene- ran-vinyl phenol) (PSVPh) copolymers via reversible addition-fragmentation chain transfer (RAFT) polymerization and their use in the synthesis of gold nanoparticles with controllable hydrophilicity

A facile approach to prepare thiol-terminated poly(styrene- ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene- ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxy-pendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers.

Living cationic sequential block copolymerization: synthesis and characterization of poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) triblock copolymers

The synthesis of well-defined poly(4-(2-(tert-butyldimethylsiloxy)ethyl)-styrene-b-isobutylene-b-4-(2-(tert-butyldimethylsiloxy)ethyl)styrene)(PTBDMES-b-PIB-b-PTBDMES) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) and 4-(2-(tert-butyldimethylsiloxy)ethyl)styrene (TBDMES) using the capping-tuning technique in a one-pot procedure in methylcyclohexane/CH3Cl at −80 °C. Deprotection of the precursor triblock copolymer with tetrabutylammonium fluoride yielded poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) (PHOES-b-PIB-b-PHOES), with pendant hydroxyl groups along the hydrophilic backbone chains. FT-IR, NMR confirmed that hydrolysis was complete.

Coordination chemistry with phosphine and phosphine oxide-substituted hydroxyferrocenes

New unsymmetrical hydroxyferrocenes were synthesised from dibromoferrocene. The oxygen heteroatom was introduced via lithiation and quenching with bis-trimethylsilylperoxide followed by hydrolysis to unmask the hydroxyl functionality. The coordination chemistry of 1'-(diphenylphosphino)-1-hydroxyferrocene 2 was explored with palladium and rhodium precursors. A dinuclear palladium methyl complex with bridging ferrocenyloxo groups was obtained from the reaction between 2 and (cyclooctadiene)methylchloropalladium(II). With tetracarbonyldichlorodirhodium(I), two complexes were isolated. The major product was a bis ligand cis phosphine ligated complex with one ligand bound in a chelating mode and one with a pendant hydroxyl group. A minor product was crystallographically characterised as a dinuclear ferrocenyloxo-bridged rhodium carbonyl complex. The coordination chemistry of 2 and the corresponding phosphine oxide 3 was examined with group 4 metals and the resulting complexes examined as ethylene polymerisation catalysts. The ligands were found to bind in either a chelating fashion or with pendant phosphine donors. In all cases, low to moderately active ethylene polymerisation catalysts were found. The catalysts were very unstable and catalyst residues were observed in the isolated polymer indicating a short catalyst lifetime.

Citric-Acid-Derived Photo-Cross-Linked Biodegradable Elastomers

Citric-acid-derived thermally cross-linked biodegradable elastomers (CABEs) have recently received significant attention in various biomedical applications, including tissue-engineering orthopedic devices, bioimaging and implant coatings. However, citric-acid-derived photo-cross-linked biodegradable elastomers are rarely reported. Herein, we report a novel photo-cross-linked biodegradable elastomer, referred to as poly(octamethylene maleate citrate) (POMC), which preserves pendant hydroxyl and carboxylic functionalities after cross-linking for the potential conjugation of biologically active molecules. Pre-POMC is a low-molecular-mass pre-polymer with an average molecular mass between 701 and 1291 Da. POMC networks are soft and elastic with an initial modulus of 0.07 to 1.3 MPa and an elongation-at-break between 38 and 382%. FT-IR–ATR results confirmed the successful surface immobilization of type-I collagen onto POMC films, which enhanced in vitro cellular attachment and proliferation. Photo-polymerized POMC films implanted subcutaneously into Sprague–Dawley rats demonstrated minimal in vivo inflammatory responses. The development of POMC enriches the family of citric-acid-derived biodegradable elastomers and expands the available biodegradable polymers for versatile needs in biomedical applications.

Synthesis and Ring-Opening Polymerization of 5-Azepane-2-one Ethylene Ketal: A New Route to Functional Aliphatic Polyamides

A functional derivative of ε-caprolactam, 5-azepane-2-one ethylene ketal or γ-ethylene ketal ε-caprolactam, has been synthesized by a very straightforward and highly efficient Beckmann rearrangement reaction. Homopolymers of this new monomer and its copolymers with ε-caprolactam have been synthesized by anionic ring-opening polymerization using N-acetyl-ε-caprolactam and NaH. The ketone groups can be easily released by deacetalyzation, and subsequent reaction leads to complete reduction to hydroxyl pendant groups. The ketone-containing (co)polymers respond sensitively to both thermal and photo-cross-linking in this novel class of materials. These new aliphatic polyamides bearing either ketone or hydroxyl pendant groups provide entries into a large number of application areas.

Chiral copolymers of (R)‐N‐(1‐phenylethyl) methacrylamide and 2‐hydroxyethyl methacrylate: copolymerization characteristics and chiroptical properties

AbstractThe aim of this investigation was the copolymerization of a chiral monomer, (R)‐N‐(1‐phenylethyl) methacrylamide, with an achiral monomer, 2‐hydroxyethyl methacrylate (HEMA). The copolymerization characteristics as well as the chiroptical properties (optical rotation and circular dichroism) and their variation with copolymer composition and temperature are discussed. The copolymers are statistical and enriched in HEMA. The monomer reactivity ratio of the chiral monomer (r1) is 0.133 whereas that of HEMA (r2) is 1.042 based on the Kelen–Tudos method. The sequence of consecutive chiral monomer units predominates for a feed composition between 0.5 and 0.9 (mole fraction). On the other hand, the sequence of HEMA is uniform and it predominates for a feed composition of around 0.5 (mole fraction). The chiroptical properties of the copolymers do not vary linearly with the content of chiral units in the copolymers. The optical rotation and circular dichroism attain optimum values above 30–40 mol% of chiral monomer units in the copolymers. However, the circular dichroism of the copolymers varies linearly with the temperature. The chiral monomer being a more bulky structure is less reactive than HEMA. The nonlinear variation of chiroptical properties of the copolymers with the content of chiral units may be due to the secondary interaction in the copolymers associated with the hydrogen bonding involving the amide linkage (CONH) present in the pendant chromophore of the chiral monomer as well as the hydroxyl pendant group of HEMA and also the aromatic π–π interaction. Copyright © 2009 Society of Chemical Industry

Thermal Degradation of Condensed Tannins from Radiata Pine Bark

In order to understand the influence of the inherent chemistry on the relative thermal stability of condensed tannins, the thermal degradation behaviors of various radiata pine bark extracts have been investigated using thermogravimetric analysis (TGA). Generally, results suggest pine bark extract fractions may be readily processed at temperatures below 200°C if co-extracted polysaccharides contents are minimized. Those extracts possessing greater carbohydrate content and lower tannin purity tend to have decreased thermal stability. The initial onset temperature for degradation of relatively crude extracts with high proportions of carbohydrate contents were relatively low (ca. 150°C), whereas extract purification to < 5% carbohydrate content gave increases in thermal stability of at least 50°C. The complicity of the carbohydrate content in the degradation of the tannin samples was also supported by calculated Ozawa activation energies and modulated TGA experiments. While no increase in the thermal stability was gained by acetylating the pendant hydroxyl groups of the pine bark tannin extract, chemical variations such as sulfonation have a large effect on thermal degradation, promoting lower degradation temperatures.

The Influence of Pendant Hydroxyl Groups on Enzymatic Degradation and Drug Delivery of Amphiphilic Poly[glycidol‐block‐(ε‐caprolactone)] Copolymers

An amphiphilic diblock copolymer PG-b-PCL with well-controlled structure and pendant hydroxyl groups along hydrophilic block was synthesized by sequential anionic ring-opening polymerization. The micellization and drug release of PG-b-PCL copolymers using pyrene as a fluorescence probe were investigated for determining the influences of copolymer composition and lipase concentration on drug loading capacity and controlled release behavior. The biodegradation of PG-b-PCL copolymers was studied with microspheres as research samples. It has been concluded that the polar hydroxyl groups along each repeat unit of hydrophilic PG block in PG-b-PCL copolymer have great influences on drug encapsulation, drug release, and enzymatic degradation of micelles and microspheres.

Synthesis and Characterization of Hydroxyl-Functionalized Caprolactone Copolymers and Their Effect on Adhesion, Proliferation, and Differentiation of Human Mesenchymal Stem Cells

The aim of this study was to develop new hydrophilic polyesters for tissue engineering applications. In our approach, poly(benzyloxymethyl glycolide-co-epsilon-caprolactone)s (pBHMG-CLs) were synthesized through melt copolymerization of epsilon-caprolactone (CL) and benzyl-protected hydroxymethyl glycolide (BHMG). Deprotection of the polymers yielded copolymers with pendant hydroxyl groups, poly(hydroxymethylglycolide-co-epsilon-caprolactone) (pHMG-CL). The synthesized polymers were characterized by GPC, NMR, and DSC techniques. The resulting copolymers consisting of up to 10% of HMG monomer were semicrystalline with a melting temperature above body temperature. Water contact angle measurements of polymeric films showed that increasing HMG content resulted in higher surface hydrophilicity, as evidenced from a decrease in receding contact angle from 68 degrees for PCL to 40 degrees for 10% HMG-CL. Human mesenchymal stem cells showed good adherence onto pHMG-CL films as compared to the more hydrophobic PCL surfaces. The cells survived and were able to differentiate toward osteogenic lineage on pHMG-CL surfaces. This study shows that the aforementioned hydrophilic polymers are attractive candidates for the design of scaffolds for tissue engineering applications.

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

AbstractIn this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)3] successfully yielded linear polyesters having hydroxyl functionality (Mn = ca. 1.0 × 104). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009

2114 Design of tumor targeting magnetic resonance imaging (MRI) agent based on gold/iron-oxide composite nanoparticle

A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene-ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxy-pendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers.

Synthesis of well-defined amphiphilic graft copolymer bearing poly(2-acryloyloxyethyl ferrocenecarboxylate) side chains via successive SET-LRP and ATRP

A series of well-defined ferrocene-based amphiphilic graft copolymers, consisting of poly(N-isopropylacrylamide)-b-poly(ethyl acrylate) (PNIPAM-b-PEA) backbone and poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) side chains, were synthesized by the combination of single-electron-transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). A new ferrocene-based monomer, 2-(acryloyloxy)ethyl ferrocenecarboxylate (AEFC), was prepared first and it can be polymerized via ATRP in a controlled way using methyl 2-bromopropionate as initiator and CuBr/PMDETA as catalytic system in DMF at 40 °C. PNIPAM-b-PEA backbone was synthesized by sequential SET-LRP of NIPAM and HEA at 25 °C using CuCl/Me6TREN as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with α-bromoisobutyryl bromide. The targeted well-defined graft copolymers with narrow molecular weight distributions (Mw/Mn < 1.20) were synthesized via ATRP of AEFC initiated by the macroinitiator. The electro-chemical behaviors of PAEFC homopolymer and PNIPAM-b-(PEA-g-PAEFC) graft copolymer were studied by cyclic voltammetry. Micellar properties of PNIPAM-b-(PEA-g-PAEFC) were investigated by transmission electron microscopy and dynamic light scattering. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4346–4357, 2009

Nanostructured hybrid hydrogels prepared by a combination of atom transfer radical polymerization and free radical polymerization

A new method to prepare nanostructured hybrid hydrogels by incorporating well-defined poly(oligo (ethylene oxide) monomethyl ether methacrylate) (POEO 300MA) nanogels of sizes 110–120 nm into a larger three-dimensional (3D) matrix was developed for drug delivery scaffolds for tissue engineering applications. Rhodamine B isothiocyanate-labeled dextran (RITC-Dx) or fluorescein isothiocyanate-labeled dextran (FITC-Dx)-loaded POEO 300MA nanogels with pendant hydroxyl groups were prepared by activators generated electron transfer atom transfer radical polymerization (AGET ATRP) in cyclohexane inverse miniemulsion. Hydroxyl-containing nanogels were functionalized with methacrylated groups to generate photoreactive nanospheres. 1H NMR spectroscopy confirmed that polymerizable nanogels were successfully incorporated covalently into 3D hyaluronic acid-glycidyl methacrylate (HAGM) hydrogels after free radical photopolymerization (FRP). The introduction of disulfide moieties into the polymerizable groups resulted in a controlled release of nanogels from cross-linked HAGM hydrogels under a reducing environment. The effect of gel hybridization on the macroscopic properties (swelling and mechanics) was studied. It is shown that swelling and nanogel content are independent of scaffold mechanics. In-vitro assays showed the nanostructured hybrid hydrogels were cytocompatible and the GRGDS (Gly–Arg–Gly–Asp–Ser) contained in the nanogel structure promoted cell–substrate interactions within 4 days of incubation. These nanostructured hydrogels have potential as an artificial extracellular matrix (ECM) impermeable to low molecular weight biomolecules and with controlled pharmaceutical release capability. Moreover, the nanogels can control drug or biomolecule delivery, while hyaluronic acid based-hydrogels can act as a macroscopic scaffold for tissue regeneration and regulator for nanogel release.

PMHDO-g-PEG Double-Bond-Based Amphiphilic Graft Copolymer: Synthesis and Diverse Self-Assembled Nanostructures

Self-assembly behavior of a double-bond-based amphiphilic graft copolymer consisting of hydrophobic polyallene backbone and hydrophilic poly(ethylene glycol) side chains in tetrahydrofuran (THF)/water was investigated. Polyallene backbone was first prepared via living coordination polymerization of 6-methyl-1,2-heptadien- 4-ol (MHDO) initiated by [(η3-allyl)NiOCOCF3]2. The targeted amphiphilic graft copolymer with relative narrow molecular weight distribution (Mw/Mn = 1.22) was synthesized by the coupling reaction between the pendant hydroxyls of the backbone and acyl chloride end group of poly(ethylene glycol) via the grafting-onto approach. The critical micelle concentration (cmc) was determined by the fluorescence probe technique. Micelle morphologies could be well tuned by water content, initial copolymer content, and ion strength. In particular, this kind of achiral copolymer could aggregate to form chiral helical nanostructures under given conditions.

The influence of side group modification in polyphosphazenes on hydrolysis and cell adhesion of blends with PLGA

Polyphosphazenes have been synthesized with tris(hydroxymethyl)amino methane (THAM) side groups and with co-substituents glycine ethyl ester and alanine ethyl ester. The THAM side group was linked to the polyphosphazene backbone via the amino function. The three pendent hydroxyl functions on each THAM side group were utilized for hydrogen bonding association with poly(glycolic–lactic acid) (PLGA). Co-substitution of the polyphosphazene with both THAM and glycine or alanine ethyl esters was employed to avoid the insolubility of the single-substituent THAM-substituted polyphosphazenes. Both poly[(tris(hydroxymethyl)aminomethane)(ethyl glycinato)phosphazene] and poly[(tris(hydroxymethyl)aminomethane)(ethyl alanato)phosphazene] (1:1 ratio of side groups) were blended with PLGA (50:50) or PLGA (85:15). DSC analysis indicated miscible blend formation, irrespective of the detailed molecular structure of the polyphosphazene or the composition of PLGA in the blend. Hydrolysis studies of the polyphosphazene:PLGA (50:50) blends indicated that the PLGA component hydrolyzed more rapidly than the polyphosphazene. Primary osteoblast cell studies showed good cell adhesion to the polymer blends during 14 days, but subsequent limited cell spreading due to increased surface roughness as the two polymers eroded at different rates.

Synthesis and characterization of chemically cross-linked polyimide–siloxane hybrid films

Abstract Chemically cross-linked polyimide and silica hybrid films were prepared through the sol–gel processing. PI matrix was prepared by the reaction of pyromellitic dianhydride with a mixture of diamines e.g., oxydianiline and 2,5-diaminohydroquinon (2,5-DAHQ) to include pendant hydroxyl groups on the chain. These groups were reacted further with isocyanatopropyltriethoxysilane. An appropriate amount of tetraethoxysilane was then added and the sol–gel process was carried out to condense ethoxy groups from both types of silanes thus producing chemically bonded composite films. The films with different silica contents were evaluated by a variety of techniques including FTIR, 29Si NMR, SEM, tensile, thermal, mechanical and thermogravimetric analyses. The chemical interaction between the phases brought about an intimate dispersion of the two phases, which resulted in the formation of nano-sized co-continuous domains. The tensile modulus of such films was higher and thermal expansion coefficient was much lower than those with similar silica contents without inter-phase bonding.

Synthesis of Linear Polyether Polyol Derivatives As New Materials for Bioconjugation

Linear polyether polyol (PEP) consisting of glycidol as repeating units is a flexible hydrophilic aliphatic polymer. The polyether main chain is similar to the widely used, biocompatible polymer poly(ethylene glycol) (PEG). While linear PEG has one or two terminal hydroxyl group(s), linear PEP distinguishes itself by the large number of pendant hydroxyl groups along the polyether main chain. We propose that this property of PEP represents a major advantage over PEG, namely, by providing multiple anchorage points and increasing the possibility for introducing different functional groups. As a first step to establishing PEP as a bioconjugation material, we modified the pendant hydroxyl groups on PEP and prepared a series of mono- and heterobifunctional derivatives with the potential to join various drug entities and biomolecules. The synthesis methods and the results of characterization are reported here.

PNIPAM‐b‐(PEA‐g‐PDMAEA) double‐hydrophilic graft copolymer: Synthesis and its application for preparation of gold nanoparticles in aqueous media

AbstractA series of well‐defined double‐hydrophilic graft copolymers, consisting of poly(N‐isopropylacrylamide)‐b‐poly(ethyl acrylate) (PNIPAM‐b‐PEA) backbone and poly(2‐(dimethylamino)ethyl acrylate) (PDMAEA) side chains, were synthesized by the combination of single‐electron‐transfer living radical polymerization (SET‐LRP) and atom‐transfer radical polymerization (ATRP). PNIPAM‐b‐PEA backbone was first prepared by sequential SET‐LRP of N‐isopropylacrylamide and 2‐hydroxyethyl acrylate at 25 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system followed by the transformation into the macroinitiator by treating the pendant hydroxyls with 2‐chloropropionyl chloride. The final graft copolymers with narrow molecular weight distributions were synthesized by ATRP of 2‐(dimethylamino)ethyl acrylate initiated by the macroinitiator at 40 °C using CuCl/tris(2‐(dimethylamino)ethyl)amine as catalytic system via the grafting‐from strategy. These copolymers were employed to prepare stable colloidal gold nanoparticles with controlled size in aqueous solution without any external reducing agent. The morphology and size of the nanoparticles were affected by the length of PDMAEA side chains, pH value, and the feed ratio of the graft copolymer to HAuCl4. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1811–1824, 2009

Polyimide-silica Hybrids: Structural and Morphological Investigations

Polyimide (PI) containing pendant hydroxyl functional groups have been employed for preparation of PI-silica hybrids through the sol-gel process. A stoichiometric amount of pyromellitic dianhydride (PMDA) was reacted with a mixture of oxydianiline (ODA) and 3,3′-diamino-4,4′-dihydroxybiphenyl (DAHP) in dimethylacetamide (DMAc) solvent to prepare the precursor poly(amic acid) (PAA) solution for the PI. Various proportions of tetraethoxysilane (TEOS) were mixed with PAA to prepare PI-silica hybrids through sol-gel process. The structure and morphology of these hybrids were investigated with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), optical surface profilometery, and Fourier transform infrared (FTIR) spectroscopy and compared with the one in which the matrix was prepared from PMDA and ODA with no pendant hydroxyl functionalities. Formation of silica lean and silica rich phases (SLP and SRP) as a result of formation of nano-sized silica clusters with diffused boundaries, dispersed in the matrix and their agglomerates, respectively, along with totally different morphology suggest a strong influence of hydroxyl groups in controlling the morphology of PI-silica hybrids. A model namely “Retain and React” has been introduced to explain observed structure.

Functionalizable biodegradable photocrosslinked elastomers based on 2-oxepane-1,5-dione

The use of aliphatic polyesters for biomedical applications is limited by the lack of functionality of their backbones. The aim of the following study was to develop a novel elastic scaffold material containing functional groups to be used for future derivatization to tether peptide ligands to support cell adhesion, migration, and differentiation. The elastomer was based on three-arm star copolymers composed of ε-caprolactone and a functionalized ε-caprolactone, 2-oxepane-1,5-dione, and end-terminated with acrylate groups. The elastomer thus contains a ketone and two approaches were examined for obtaining a photocrosslinkable elastomer containing functional groups: crosslinking followed by ketone reduction using sodium borohydride to generate pendant hydroxyl groups, and reaction of the ketone with hydrazines. Reduction of the ketone lead to degradation of the elastomer through transesterification and ethanolate mediated cleavage of the polymer backbone. Reaction with hydrazines did not degrade the polymer and resulted in efficient functionalization of the elastomer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8191–8199, 2008