Synthesis of adaptative and amphiphilic polymer model conetworks by versatile combination of ATRP, ROP, and 'Click chemistry

Well-defined adaptative and amphiphilic polymer conetworks based on hydrophilic poly(N,N-dimethylamino-2-ethyl methacrylate) (PDMAEMA) and hydrophobic poly(e-caprolactone) (PCL) have been prepared by combination of ATRP, ROP, and Click chemistry. Telechelic alpha,omega-alkyne terminated PCL crosslinker was obtained by ring-opening polymerization (ROP) of CL in THF at 80 degrees C initiated by 1,4-butanediol and catalyzed by tin(II) bis 2-ethyl hexanoate (Sn(Oct)(2)), followed by the quantitative esterification of hydroxyl end-groups by activated 4-pentynoic acid. In parallel, an azido-containing PDMAEMA-based copolymer was obtained in a three-step strategy involving primarily the copolymerization of DMAEMA with newly synthesized 2(2-azidoethoxy)ethyl methacrylate (AEEMA) monomer. The latter was obtained by nucleophilic substitution of chloride atom from 2-(2-chloroethoxy)ethanol by an azide group followed by the esterification reaction of the hydroxyl group with methaerylic anhydride. The copolymerization was carried out in an equivolumic mixture of H2O and isopropanol at r.t. and initiated by a omega-bromoisobutyryl oligo PEO macroinitiator in the presence of various ligated copper(I)-based catalysts. In a last step, both polymer precursors were chemically linked by the Huisgen-1,3-dipolar cycloaddition in anhydrous THF at r.t. using CuBr complexed by 2,2 '-bipyridine ligand as catalyst. Final material was characterized by the means of DSC and SEM, both attesting of a homogeneous distribution of the PCL crosslinkers and a highly porous structure in this new amphiphilic model conetworks. (C) 2008 Wiley Periodicals, Inc.