Anisotropy across length scales: Conformation and self-assembly of coil-liquid diblock coplymers in nematic solvent

Abstract

Coil-Liq. Cryst. diblock copolymers exhibit ordered morphologies in liq. crystal (LC) solvent that reflect the interplay between microphase segregation of the coil (LC phobic) block and the spontaneous anisotropy in the local chain conformation of the LC block. The self-assembly of "end-on" and "side-on" coil-LC diblock copolymers with near const. side group liq. crystal polymer (SGLCP) block lengths and increasing coil (polystyrene) block lengths (40 kg/mol to 120 kg/mol) was investigated using SANS and TEM. SANS measurements of dil. solns. of these coil-SGLCP diblocks in aligned nematic LC solvent reveal the formation of anisotropic, self-assembled micelles. Unstained and pos.-stained TEM enabled a direct correspondence between the structural features found in the anisotropic scattering and micelle sizes. Size scales of the morphol. features at both at the network (>100 nm) and intrachain (5-100 nm) levels were examd. The shape and anisotropy of the micelle core appears to depend on both the SGLCP block and the polystyrene block lengths.