SYNTHESIS AND MORPHOLOGICAL BEHAVIOR OF SILICON-CONTAINING TRIBLOCK COPOLYMERS FOR NANOSTRUCTURE APPLICATIONS

We report the synthesis of high molecular weight triblock copolymers o f the type ABA and BAB, where A is polyisoprene (PI) and B is poly(pen tamethyldisilylstyrene) (P(PMDSS)), respectively. The volume fraction of the minority component (PI) for the ABA copolymer was 0.33, while t hat for the BAB copolymer was 0.23. The synthesis procedure of the P(P MDSS) blocks corresponded to that of polystyrene (PS), and low polydis persity with targeted compositions were achieved. The morphology of th e triblock copolymers was characterized by transmission electron micro scopy (TEM) and digital Fourier transform patterns. From TEM and diffr action analysis, the ABA polymer exhibited the double gyroid cubic mor phology, while the BAB polymer showed a P(PMDSS) spherical domain morp hology. The double gyroid morphology is the first to be reported in a silicon-containing block copolymer and consists of two three-dimension ally continuous, interpenetrating but nonintersecting networks of PI i n a matrix of P(PMDSS)). Preliminary oxidative studies using ozone or O-2-RIE on the tricontinuous phase show that nanoporous structures can be generated.