DILUTE-SOLUTIONS OF BLOCK-COPOLYMERS - 2 - TRIBLOCK COPOLYMERS

Dilute solutions of symmetric triblock copolymers ABA and BAB in a sel ective solvent, i.e., a solvent good for one type of monomers (A) and poor for the other (B), and of their constituent homopolymers mere inv estigated by exact enumeration of pair configurations of cubic lattice chains generated by a Monte Carlo method. Quantities characterizing t he size and the molecular shape were investigated as a function of the intermolecular distance between the chains. In addition, integral qua ntities of chain properties (related to concentration dependencies) we re computed. On the whole, behavior of triblock copolymers was closer to that of athermal chains than to that of Theta-homopolymers. Their a rchitecture, however, significantly influenced the details. The pair d istribution function of BAB exceeded unity at large distances as is ch aracteristic for homopolymers in Theta-solvents and poor solvents. Fur thermore, behavior characteristic of Theta-systems persisted for all d istance dependent quantities investigated for BAB at large separations . This was not however sufficiently pronounced as to be reflected in t he sign of integral quantities which again resembled those of the athe rmal system.