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A direct, non-enzymatic procedure for the synthesis of thiol-functionalized polylactones was developed and optimized by using 2-mercaptoethanol, the simplest unprotected thiol-containing initiator for cationic ring-opening polymerization, catalyzed by HCl and methanesulfonic acid in dichloromethane solutions. Thiol-functionalized polylactones with a molecular weight of up to approximately 5000 Da were obtained in a controlled manner. It was observed that acid can play the dual role of activator and initiator, and for the first time, it was shown that abundant HCl and/or ambient temperature lead to the formation of undesired α-carboxy-ω-chloro-functionalized polylactones that form in parallel with the targeted thiol-functionalized ones. A plausible pathway towards the formation of chlorinated products is proposed based on an active-chain-end mechanism, and the procedure was optimized to eliminate its contribution to the polymerization process, thus allowing for the activated-monomer mechanism to prevail. Molecular weight characterization was performed using 1 H NMR and size-exclusion chromatography. The results indicate that the polymers obtained under optimized conditions possess high SH functionality and moderate polydispersity, and that ring-opening polymerization proceeded in a controlled fashion. The proposed method allows for the preparation of metal free materials readily suitable for biomedical and/or electronic applications.

Novel hydrophilic and thermosensitive poly(N,N-diethylacrylamide-co-2-hydroxyethyl methacrylate) resins were prepared by inverse suspension polymerization with N,N′-methylenebis(acrylamide) as a crosslinker. The effects of chemical composition and degree of crosslinking on the polymerization were investigated. The polymer resins were characterized by elemental analysis, infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The thermosensitivity of the crosslinked resins was demonstrated by their lower critical swelling temperatures. The swelling and deswelling volume of the beads in water varied depending on the molar fraction of the N,N-diethylacrylamide. These beads swelled extensively in a variety of common solvents. They had high loadings of functional hydroxyl groups and were used as supports in the solid-phase synthesis of an oligopeptide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1681–1690, 2003

By free radical polymerization, we have prepared a series of water-soluble, thermosensitive copolymers based on N-isopropylacrylamide and (meth)acrylamide derivatives of cholic acid, one of the bile acids. The copolymers contained 1–7 mol-% of the (meth)acrylamide derivatives of cholic acid. The chemical composition in the copolymers was studied by NMR spectroscopy and was found to be close to the original composition of the comonomers in the feed prior to polymerization. The lower critical solution temperatures (LCST) of the polymer solutions were measured by means of differential scanning calorimetry and turbidimetry. The resulting copolymers exhibit systematic changes in their LCSTs as a function of their chemical composition, as the incorporation of hydrophobic comonomers leads to a lower LCST.

ABA and/or ABC type triblock copolymers were synthesized by living anionic and controlled radical polymerization in which poly(methyl methacrylate) was used as central block. The structural composition of these block copolymers were determined by 1 H NMR. The block length/molecular weight and microstructure of these polymers were measured by SEC. The microstructure of resultant central alkyl methacrylate block can be tailored from highly syndiotactic to highly isotactic structure by varying the solvent and/or initiator. The thermal and rheological properties of center poly(methyl methacrylate) block and poly(styrene- b - methyl methacrylate- b - styrene) tri block copolymers were studied in detail. Introduction Block copolymers are unique materials whose characteristics may be a hybrid of the individual homopolymers. The properties of the block copolymer, such as thermal behavior, dielectric properties, and solubility, can be controlled through its composition. For example, block copolymer architecture, microstructure and sequential distribution based on poly alkyl acrylates are important parameters that impact the solubility in different solvents [1]. Synthesis of ABA type triblock copolymer can be achieved by three routes: (1) sequential monomer addition, (2) synthesis of AB diblock followed by linking reaction, and (3) successive polymerization of monomers starting from a difunctional macroinitiator. Block copolymerization of dienes and styrene can be initiated from either dienyl or styrenyl anionic species. ABA type triblock copolymers based on dienes and styrene can be synthesized in a controlled manner following above three routes. In the recent years, special attention has been focused on the synthesis of ABA triblock copolymers where the center block is based on poly alkyl methacrylate particularly in the area of polymer blends [2, 3]. Among various combinations, poly(styrene- methyl methacrylate) block copolymers are commonly used as model system, as these polymers are readily accessible, poly(styrene) and poly(methyl methacrylate) have nearly the same glass transition temperature and their physical properties are well-documented in literatures [4, 5]. Poly(styrene

Well-defined cleavable poly(styrene-block-ethylene oxide) polymers were prepared by living anioinc polymerization, using cumyl potassium as the initiator. These polymers contained an acid cleavable moiety, such as diphenyl methyl or anthracenyl methyl ether linkage, between polystyrene and poly ethylene oxide block. Atomic force microscopy (AFM) studies on the thin films illustrate the formation of nanoporous architecture due to acid cleavage of the polyethylene oxide fraction.