Synthesis and Characterization of PDMS Based Triblock and Pentablock Copolymers

Abstract

Poly(dimethylsiloxane)-based triblock and pentablock copolymers have been synthesized via atom transfer radical polymerization (ATRP) of styrene (St) and vinyl acetate (VAc) telomer at 60°C in the presence of CuCl/PMDETA as a catalyst system initiated with bis(bromoalkyl)-terminated PDMS macroinitiator (Br-PDMS-Br). Vinyl acetate telomers prepared from radical and controlled radical telomerization with Co(acac) 2 /DMF catalyst and ligand were used in atom transfer radical polymerization to synthesize poly(vinylacetate-b-dimethylsiloxane-b-vinylcetate) (PVAc-b-PDMS-b-PVAc) triblock copolymer and poly(vinyl acetate-b-styrene-b-dimethyl siloxane-b-styrene-b-vinyl acetate) (PVAc-b-PSt-b-PDMS-b-PSt-b-PVAc) pentablock copolymers. The PDMS-based triblock and pentablock copolymers revealed a significant effect of Co(acac) 2 /DMF on PVAc telomere, which was used in the synthesis of highly ordered block copolymer on a well-defined microstructure. The results were confirmed by 1 H-NMR and DSC indicating that a low Tg of PDMS in the microstructure of block copolymer has made the block copolymer flexible for new applications.