Synergistic combination between starch and proteins in the synthesis of new acrylic/biopolymers hybrid latexes

Abstract

The present-day environmental concerns and the decay in oil reserves have driven the efforts for developing novel eco-friendly and biodegradable materials. In this context, the use of biopolymers to replace totally or partially petroleum-derivative polymers is a promising alternative for reaching this aim. In this article, a new class of waterborne acrylic/biopolymers nanoparticles was produced by emulsion polymerization, studying the adequate combination of: (i) starch/zein bioparticles acting as seed for emulsion polymerization; (ii) casein, an amphiphilic protein with stabilization properties that avoids the use of synthetic surfactant; and (iii) a low Tg acrylic copolymer that provides film formation capability and controlled mechanical properties. Batch and semibatch polymerization strategies were explored with varied content of starch/zein bioparticles. Both methods allowed the formation of biphase hybrid nanoparticles with multilobular morphology, composed of starch/zein bioparticles as core and multisurrounding lobules of acrylic copolymer. However, the employed polymerization strategy influenced the compatibilization between the acrylic copolymer and the biopolymers phase, determining the hybrid film properties. Interestingly, clear and homogenous films were produced, which also showed an excellent performance to bond polar substrates, opening potential applications of these hybrid materials for coatings and adhesives.