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

PUIG, J.; ZUCCHI, I.A.; SCHROEDER, W.F.; WILLIAMS, R.J.J.

Ciudad de Buenos Aires

Simposio; Frontiers in Physical Sciences 2016; 2016

A large number of papers and reviews1 describing the generation of micellar or orderedstructures (cubic, cylindrical, gyroid, lamellar), in polymer networks, have been published.Vesicles are a particularly attractive morphology to be developed in nanostructured epoxythermosets.2 Vesicles formed from block copolymers (BCP) are closed, spherical objectsconsisting of a thin bilayer membrane that encases the epoxy resin. The interest in thismorphology resides on the fact that the copolymer forms only the shell and the volume of thevesicle phase consists of both the shell and the encapsulated epoxy, a small amount of theblock copolymer can function with a large effective modifier volume fraction. However, fewstudies report on nanostructured epoxy networks modified with vesicles. In all of them, thenanostructure is obtained before curing by self-assembly in the precursors, and the role ofcuring is to lock in the morphology that is already present.3This work shows a different scenario in which the vesicles are formed during polymerizationas the result of polymerization-induced self-assembly (PISA). The block copolymer PEBPEOwas selected because PEO is an epoxy-philic block which is completely miscible withthe 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 areinitially present. During the course of photopolymerization at room temperature, the selfassembledmorphology changes from micelles to vesicles. To investigate the evolution of themorphologies during the photocure reaction at room temperature, in situ SAXS measurementswere carried out.