Vesicles of PEB-b-PEO formed during polymerization induced self-assembly in an epoxy matrix

JULIETA PUIG; WALTER F. SCHROEDER; ILEANA A. ZUCCHI; ROBERTO J. J. WILLIAMS

Ciudad Autónoma de Buenos Aires

Congreso; Frontiers in Physical Sciences; 2016

International Center for Advanced Studies and Max Planck Liason Office for Latin America, in cooperation with the Kolleg Programme of the Alexander von Humboldt Foundation

A large number of papers and reviews1 describing the generation of micellar or ordered structures (cubic, cylindrical, gyroid, lamellar), in polymer networks, have been published.Vesicles are a particularly attractive morphology to be developed in nanostructured epoxy thermosets. Vesicles formed from block copolymers (BCP) are closed, spherical objects consisting of a thin bilayer membrane that encases the epoxy resin. The interest in this morphology resides on the fact that the copolymer forms only the shell and the volume of the vesicle phase consists of both the shell and the encapsulated epoxy, a small amount of the block copolymer can function with a large effective modifier volume fraction. However, fewstudies report on nanostructured epoxy networks modified with vesicles. In all of them, the nanostructure is obtained before curing by self-assembly in the precursors, and the role of curing is to lock in the morphology that is already present.This work shows a different scenario in which the vesicles are formed during polymerization as the result of polymerization-induced self-assembly (PISA). The block copolymer PEB-b-PEO was selected because PEO is an epoxy-philic block which is completely miscible with the epoxy monomer before and after curing reaction whereas PEB is an epoxy-phobic block.Under these conditions, micellar nanostructures with PEB core before curing reaction are initially present. During the course of photopolymerization at room temperature, the selfassembled morphology changes from micelles to vesicles. To investigate the evolution of the morphologies during the photocure reaction at room temperature, in situ SAXS measurements were carried out.