An atomic force microscopy study of the morphology of a triblock copolymer (BCP), sulfonated BCP, and a BCP/silicate hybrid produced by a templated sol-gel process

摘要

Hard/soft block copolymers (BCPs), where the hard block is polystyrene (PS), have useful properties that result from their ordered, microphase separated equilibrium morphologies. The hard block domains provide, in essence, stable, thermally-reversible, physical crosslinks at low temperature. This feature provides rubber elastic behavior if the PS blocks constitute the major phase. When the hard blocks are disrupted at higher temperatures, that is, above an order-disorder transition, flow can occur, which in turn allows for thermal processing. Depending on the volume fraction of the PS phase (f_(ps)), these BCPs can exhibit a wide spectrum of morphologies. PS/polydiene BCPs exhibit four primary morphologies: body-centered cubic spheres (BCC) (<～17%PS), hexagonally packed cylinders (HPC) (～17-28%), ordered bicontinuous double diamond (OBDD) (～28-34%), and lamellar (L) (up to 50%) before there is phase inversion after which the materials have the behavior of rubber-toughened plastics.