Silicone Macroinitiator in Atom Transfer Radical Polymerization of Styrene and Vinyl Acetate: Synthesis and Characterization of Pentablock Copolymers

Abstract

Poly(dimethylsiloxane) (PDMS) based pentablock copolymers has 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. Vinyl acetate telomer was prepared from controlled radical telomerization with Co(acac)2/DMF with PDI ≈ 1.3. Poly(vinyl acetate-b-styrene-b- dimethylsiloxane- b- styrene-b-vinyl acetate) (PVAc-b-PSt-b-PDMS-b-PSt-b-PVAc) pentablock copolymers provided a method to design block copolymer with PDMS segment, allowing us for the adjustments in the flexibility by PDMS with a large effect from its softening point (Tg), or rigidity of styrene monomer and a higher melting temperature (Tm). Penta-block copolymers were characterized by FTIR, 1HNMR, DSC, and GPC techniques. Meanwhile, the number-average molecular weights calculated from 1HNMR spectra were in very good agreement with the theoretically calculated value. It could be concluded from the 1HNMR and DSC spectrum that the pentablock copolymers of PVAc-b-PSt-b-PDMS-b-PSt-b-PVAc consisting of a PDMS center block and PSt and PVAc terminal blocks were synthesized.