Study of self-assembly of symmetric coil-rod-coil ABA-type triblock copolymers by self-consistent field lattice method

摘要

The self-assembly of symmetric coil-rod-coil ABA-type triblock copolymer melts is studied by applying self-consistent field lattice techniques in a three-dimensional space.The self-assembled ordered structures differ significantly with the variation of the volume fraction of the rod component,which include lamellar,wave lamellar,gyroid,perforated lamellar,cylindrical,and spherical-like phases.To understand the physical essence of these phases and the regimes of occurrence,we construct the phase diagram,which matches qualitatively with the existing experimental results.Compared with the coil-rod AB diblock copolymer,our results revealed that the interfacial grafting density of the separating rod and coil segments shows important influence on the self-assembly behaviors of symmetric coil-rod-coil ABA triblock copolymer melts.We found that the order-disorder transition point changes from f_(rod)=0.5 for AB diblock copolymers to f_(rod)=0.6 for ABA triblock copolymers.Our results also show that the spherical-like and cylindrical phases occupy most of the region in the phase diagram,and the lamellar phase is found stable only at the high volume fraction of the rod.