Lyotropic phase morphologies of amphiphilic block copolymers

Lyotropic phase morphologies of amphiphilic poly(butadiene-b-ethylene oxide ) (PB-PEO) block copolymers are studied using transmission electron microsc opy, small-angle X-ray scattering, small-angle neutron scattering, and pola rized optical microscopy. The PB-PEO block copolymers form type-1 lyotropic phases comprising disordered micellar solutions (L-1), spheres arranged on a bce lattice (I-1), hexagonally packed cylinders (H-1), and lamellae (L-a ). Increasing molecular weight destabilizes the I-1 and H-1 phases and lowe rs the degree of order. For high molecular weight block copolymers the incr ease in chain conformational entropy leads to the formation of the sponge p hase (L-3) Tile transmission electron micrographs allow a detailed analysis of packing defects and epitaxial relations of the block copolymer lyotropi c phases.