Synthesis and characterization of diblock and statistical copolymers based on hydrolyzable siloxy silylester methacrylate monomers

Abstract

Statistical and diblock copolymers of bis(trimethylsiloxy)methylsilyl methacrylate (MATM2), a hydrolyzable monomer containing a silylester and a siloxane group, and methyl methacrylate (MMA) were synthesized by the RAFT process. The controlled character of the MATM2 RAFT polymerization using 2-cyanoprop-2-yl-dithiobenzoate (CPDB) or S-(2-cyanoprop-2-yl)-S-dodecyltrithiocarbonate as chain transfer agents was assessed by linear pseudo-first-order kinetics, linear molar mass growth with monomer conversion and low molar-mass dispersity. The hydrolysis kinetics of pMATM2 homopolymers was investigated by in situ1H-NMR and compared to several methacrylic homopolymers bearing hydrolyzable tri-alkylsilylester side groups. pMATM2-block-pMMA diblock copolymers were synthesized by in situ chain extension with methyl methacrylate, using pMATM2-CPDB as a macro-CTA. p(MATM2-stat-MMA) statistical copolymers were synthesized by simultaneous polymerization of MATM2 and MMA by the RAFT process. The monomer reactivity ratios for MATM2 (r1 = 1.29) and MMA (r2 = 0.62) were obtained from the Mayo Lewis equation using the least-squares method. All the copolymers synthesized by the RAFT process had molar masses close to the targeted values and low dispersities (ĐM < 1.15). DSC analysis and contact angle measurements revealed the influence of the copolymer microstructure (statistical or diblock) on their glass transition temperature and surface energy.