Peel Adhesive Properties of Epoxy / Acrylic Block Copolymer Blends;Effect of in-situ Formed Nanophase Structures

Abstract

The phase structures of diglycidyl ether of bisphenol-F / 4,4́-methylene-bi（s 2-ethylaniline）（ MBOEA）/poly（methyl methacrylate）-b-poly（n-butyl acrylate）-b-poly（methyl methacrylate）（ PMMA-b-PnBA-b-PMMA）triblock copolymer blends and their peel adhesive properties were studied. Heat dissolving process of theacrylic BCP in the amine（ MBOEA） generated in-situ carboxylic acids in the PMMA segment of the BCP. Theacid values in the BCPs were controlled in the dissolving process, which enabled to form different nanostructuresfrom the same composition（ 5wt%BCP） in epoxy/amine mixture. Three types of nanostructures wereobserved using transmission electron microscopy（ TEM）, that were curved lamellar structures, coexistingstructures of worm-like micelles and vesicles, and spherical micelles. For the three types of nanostructures,the T-peel adhesive strength were evaluated. The highest adhesive strength was obtained from the coexistingnanostructure of worm-like micelles and vesicles, which was 2.5 times improved in the adhesive strength incomparison with the cured epoxy resin without BCP. The T-peel adhesive strength had good relationship withthe fracture toughness of the adhesive resins, which were depending on the nanostructures of the cured epoxyblends.