Tuning the phase behavior of polystyrene-block-poly(n-alkyl methacrylate) copolymers by introducing random copolymer for methacrylate block

A study was conducted to tune the phase behavior of polystyrene-block- poly(n-alkyl methacrylate) copolymers by introducing random copolymer for methacrylate block. Polystyrene-block-poly(n-octyl-ran-methyl) methacrylate copolymers (PS-b-Pn(O-r-M)MA) was selected for conducting the investigations and it was found that (PS-b-Pn(O-r-M)MA) exhibited closed-loop phase behavior when the total molecular weight and the composition of the random copolymer block was controlled. Symmetric (PS-b-Pn(O-r-M)MAs with various molecular weights were synthesized by sequential anionic polymerization of styrene and the monomer mixture composed of MMA and n-OMA in dried tetrahydrofuran (THF) at -78 °C under a purified argon atmosphere with sec-butyllithium (sec-BuLi) as an indicator and dried LiCl as an additive to prepare narrow molecular weight distribution for methacrylate moiety.