Control of nanostructures in epoxy/acrylic block copolymer blends by the in situ generation of functional groups

Abstract

The phase structures obtained from blends consisting of an epoxy resin, an aromatic amine and a PMMA-b-PnBA-b-PMMA triblock copolymer (BCP) were studied, in terms of the effect of the process used to blend the BCP into the epoxy/amine mixture. The thermal dissolution of the BCP in the amine was found to promote the in situ generation of carboxylic acids in the PMMA segments of the BCP. This enhanced the compatibility of the BCP with the cured epoxy/aromatic amine resin, allowing the self-assembly of the BCP to form nanophase structures in the polymeric matrix. This work also determined that modification of the heating conditions was an effective means of controlling the quantity of carboxyl groups generated (that is, the acid value). Such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles and spheres, from epoxy/amine/BCP blends having the same composition. The blends of epoxy/amine/acrylic block copolymer (BCP) provided nanophase structures by optimizing the dissolution process of BCP. The thermal dissolution of the BCP in the amine promoted the in situ formation of carboxylic acids. Tuning the amount of carboxylic acids changed the phase structure, such variations led to the formation of different types of micelle structures, such as curved lamellae, coexisting of worm-like micelles and vesicles, and spherical micelles from epoxy/amine/BCP blends having the same composition.