Nanocellulose, a Renewable Biobased Functional/Reinforcement Additive for Composite Coating Materials: A Review

With the increasing demand for coatings toward improved comprehensive performance and the implementation of sustainable development strategies, nanocellulose (NC), a renewable and easily biodegradable biomaterial, has been identified as a promising and potential functional/reinforcement additive during the preparation of composite coating materials. Based on recent research, this paper reviews NC itself and its emerging application areas of functionality/enhancement in composite coating materials. In this review, NC materials are divided into two categories of pure NC materials and NC-based composite materials to make a more comprehensive induction of these nanometer-scale materials. The main existing forms and typical examples of NC in various dimensions are introduced followed by a generalization of its preparation and modification methods. NC has been widely utilized to render functionality or strengthen the performance of composite coating materials via its illustrious performance and unparalleled reticulate structure. On one hand, this paper discusses the scientific investigation advances on the multifunctional properties of NC or modified NC that endow coatings with hydrophobicity, dispersibility, corrosion resistance, self-healing, and antibacterial properties. On the other hand, the latest research on polyurethane, acrylate, alkyd ester (oil-modified polyester), and epoxy coatings prepared by utilizing NC as an enhancer is presented.