Designing Waterborne Protective Coatings Through Manipulating the Nanostructure of Acrylic-Based Nanocomposites

Abstract

AbstractWaterborne coatings with intended functionalities have been designed by manipulating acrylic-based nanocomposites with different nanostructures. Taking advantage of the favorable structure of acrylic copolymers, three waterborne coatings with various desired properties were created through molecular engineering either by copolymerizing with other components or through nanocomposite formation. This approach was demonstrated by synthesizing acrylic-based waterborne coatings with three different nanostructures, namely homogeneous, worm-like, and spherical-like nanostructures. The properties of coating samples prepared by this new approach and by traditional physical blending were compared experimentally, which revealed that the incorporation of 3-methacryloxypropyltrimethoxysilane (MPS)-modified nanoparticle TiO2 in an acrylic base enabled the formation of a nanocomposite with nanoparticles uniformly distributed in the acrylic base. The coating film with this acrylic-TiO2 nanocomposite showed significantly better UV absorption performance than the coating made by physical blending. The copolymerization of acrylic copolymers with an organic polymer (alkyd) created a worm-like nanostructure of acrylic–alkyd composite that allowed uniform distribution of the acrylic–alkyd nanocomposite in a more closely packed dense coating film, leading to enhanced barrier property and significantly improved corrosion resistance as confirmed by electrochemical impedance spectroscopy and salt spray tests. The copolymerization of acrylic monomers with an inorganic polymer (polydimethylsiloxane [PDMS]) led to a spherical-like nanostructure of acrylic–PDMS composite film. The formation of this nanostructure arose from the migration of PDMS segments, and a PDMS-rich phase formed on the film’s surface, which resulted in a coating film with PDMS functionalities such as low dirt-picking behavior. Overall, these three cases demonstrated that acrylic copolymer are an excellent base for developing various nanocomposite waterborne coatings with different functionalities through copolymerization and that the nanocomposites with different nanostructures have a significant influence on the coatings’ performance.