Synthesis of biocompatible and biodegradable block copolymers of polyvinyl alcohol‐block‐poly(ε‐caprolactone) using metal‐free living cationic polymerization

Abstract

Applications of metal‐free living cationic polymerization of vinyl ethers using HCl·Et2O are reported. Product of poly(vinyl ether)s possessing functional end groups such as hydroxyethyl groups with predicted molecular weights was used as a macroinitiator in activated monomer cationic polymerization of ε‐caprolactone (CL) with HCl·Et2O as a ring‐opening polymerization. This combination method is a metal‐free polymerization using HCl·Et2O. The formation of poly(isobutyl vinyl ether)‐b‐poly(ε‐caprolactone) (PIBVE‐b‐PCL) and poly(tert‐butyl vinyl ether)‐b‐poly(ε‐caprolactone) (PTBVE‐b‐PCL) from two vinyl ethers and CL was successful. Therefore, we synthesized novel amphiphilic, biocompatible, and biodegradable block copolymers comprised polyvinyl alcohol and PCL, namely PVA‐b‐PCL by transformation of acid hydrolysis of tert‐butoxy moiety of PTBVE in PTBVE‐b‐PCL. The synthesized copolymers showed well‐defined structure and narrow molecular weight distribution. The structure of resulting block copolymers was confirmed by 1H NMR, size exclusion chromatography, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5169–5179, 2009

Cationic polymerization of isobutyl vinyl ether in an imidazole-based ionic liquid: characteristics and mechanism

“…The stereoregularity of the product polymers was revealed from the peaks of methylene carbons of the main chains in the 13 C-NMR spectra recorded in CDCl 3 . [34][35][36][37][38] The meso diad values of the polymers produced in [omim][BF 4 ] were in the range of 55-58% (in Fig. 5), which were lower than those obtained in the dichloromethane system (61-67%).…”

Cationic polymerization of vinyl ethers and p‐methoxystyrene by a benign initiating system: Silver salt/arylmethyl halide/dialkyl sulfide

“…Living polymerization is an indispensable tool for preparing various polymeric materials with well‐defined architecture such as narrow molecular weight distribution (MWD), predetermined molecular weight, and controllable end groups . Recently, living cationic polymerization of vinyl monomers has been used for the precision synthesis of various functional polymers, such as well‐defined block polymers, star‐shaped polymers, and stimuli‐responsive polymers . Along with this development, a wide variety of Brønsted acids and Lewis acids has been used as catalysts, since the living cationic polymerization of vinyl ethers (VEs) using the HI/I 2 system was achieved …”

“…1,2 Recently, living cationic polymerization of vinyl monomers has been used for the precision synthesis of various functional polymers, such as welldefined block polymers, star-shaped polymers, and stimuliresponsive polymers. [3][4][5][6][7] Along with this development, a wide variety of Brønsted acids and Lewis acids has been used as catalysts, since the living cationic polymerization of vinyl ethers (VEs) using the HI/I 2 system was achieved. 8 In most of the living cationic polymerization procedures for VEs, protonic acids (e.g., CF 3 COOH, HCl, and HI) are commonly used as cationogens and react with VEs to generate acid adducts.…”

Synthesis of thermoresponsive block and graft copolymers via the combination of living cationic polymerization and RAFT polymerization using a vinyl ether-type RAFT agent

“…In the recent years, we also have reported some methods to prepare well-defined block copolymers between vinyl ethers and other monomers such as acrylates, styrenes and acrylamides, and controlled molecular weight involving two mechanism polymerizations, such as living cationic polymerization and RAFT polymerization [16][17][18][19]. For the combination of living cationic polymerization and RAFT polymerization, the cationic polymerization of vinyl ether is initiated from a proton derived from the carboxylic RAFT agents and then the polymerization progressed smoothly under SnBr 4 initiation system in the presence of an additive such as ethyl acetate and 1,4-dioxane.…”