Synthesis and surface attachment of ABC triblock copolymers containing glassy and rubbery segments

The synthesis of an ABC triblock copolymer containing glassy and rubbery segments was conducted using a combination of living anionic and atom transfer radical polymerizations (ATRP). A poly(dimethylsiloxane) (pDMS) macroinitiator (M̄_{n SEC} = 6 200; M̄_w/M̄ _n = 1.19) was prepared by living anionic ring-opening polymerization, followed by hydrosilation reactions to incorporate 2-bromoisobutyrate end groups for initiation of ATRP. The ATRP of styrene (S) using the pDMS macroinitiator yielded a diblock copolymer (M̄_{n SEC} = 66730; M̄_w/M̄_n = 1.38). Chain extension of the pDMS-b-pS macroinitiator with 3-(dimethoxymethylsilyl)propyl acrylate (DMSA) by ATRP yielded an ABC triblock copolymer. The latter reactive segment was covalently attached to silanol groups on a silicon wafer. The presentation of either glassy pS or flexible pDMS segments of the brushes attached to the surface was reversibly controlled by treatment with selective solvents for each segment.