MOLECULAR-DYNAMICS SIMULATION OF A SINGLE-COMPONENT MOLECULAR COMPOSITE - POLY(P-PHENYLENE BENZOBISTHIAZOLE) META-POLY(ARYL ETHER KETONE) BLOCK-COPOLYMER/

Molecular dynamics simulations were performed with a model of a single -component molecular composite in the form of a block copolymer compos ed of poly(p-phenylene benzobisthiazole) rigid-rod and flexible meta-p oly(aryl ether ketone) subunits. The molecular composite concept, appl ied to improve the compressive strength of rigid-rod polymers and to i mprove their solubility, relies on a uniform distribution of rods in a coil-like matrix. Pair distribution functions, orientation correlatio n functions and correlation volumes calculated from equilibrium dynami cs trajectories of bulk copolymer, coil homopolymer and rigid-rod homo polymer systems imply that, while inter-rod spacing is only slightly i ncreased in the copolymer, correlation of rod orientation is greatly r educed but to a somewhat lesser extent than previously found for a gra ft copolymer composed of identical subunits. Conformations of the flex ible blocks extend to accommodate the partial rod alignment. The block copolymer topology appears to be a viable alternative to the hairy-ro d graft copolymer as a single-component molecular composite.