Theory of microphase separation of homopolymer-oligomer mixtures

TL;DR

This paper develops a theoretical model for the microphase separation in homopolymer-oligomer mixtures, explaining the periodic layered structures and their temperature dependence based on associative interactions.

Contribution

It introduces a novel theoretical framework linking oligomer association dynamics to the structural period and phase transition behavior.

Findings

Temperature dependence of structure period explained

Point of order-disorder transition predicted

Model applies to both ionic and hydrogen-bonded systems

Abstract

Microphase separated structure consisting of the periodic alternation of the layers of stretched homopolymer chains surrounded by perpendicularly oriented oligomeric tails is studied for both, strongly bonded (ionic) systems and weakly (hydrogen) bonded systems. Our approach is based on the fact that the structure period is determined by alternating associations between the head group of the surfactant and the interacting group of the polymer. Oligomer distribution along the homopolymer chain is described by the effective equation of motion with the segment number playing the role of time. As a result, experimentally observed temperature dependence of the structure period, as well as the dependence of the point of order--disorder transition are determined as functions of the oligomeric fraction.