Incorporating cellulose nanocrystals into waterborne acrylic coatings towards eco-friendly formulations

Waterborne coatings are primarily produced with hard acrylic polymers to provide adequate hardness and strength. Hard acrylic latexes cannot form a continuous polymer film at ambient conditions; therefore, coating formulations include volatile organic compounds (VOCs) as coalescents to ensure film formation. However, VOCs evaporate during drying of the coatings, resulting in environmental and health concerns. Successfully balancing hardness while reducing VOCs and ensuring proper film formation is challenging. This dissertation explores the incorporation of cellulose nanocrystals (CNCs) as performance additives to improve the hardness and strength of ambient film-forming latex coatings. CNCs could be placed in either the aqueous phase or the polymer phase as an additive to acrylic latex particles. This research aims to determine optimal methods of CNC addition to acrylic latexes, identify the challenges in controlling the CNC location in the latex system, and characterize film formation and properties of final dried films. Three major studies were conducted and presented as three main chapters (Chapter 2, Chapter 3, and Chapter 4). Chapter 2 highlighted the potential of CNC to be used as an aqueous additive in the acrylic binders and encouraged further investigations for reformulating waterborne acrylic products with CNCs. Chapter 3 demonstrated a framework to functionalize the CNC surface with acryloyl groups and acrylic polymers. This framework expands the use of CNCs by offering a versatile modification route and macromonomer functionality. Chapter 4 explored the incorporation of functionalized CNCs into the polymer phase of latex via miniemulsion polymerization. This chapter underlined the importance of the compatibility of CNCs with the monomer phase to enable the partition of CNCs into the polymer phase in miniemulsion. Overall, the findings in this dissertation are expected to guide researchers in the paint, coating, and cosmetic industries to extend the use of CNCs in waterborne formulations.Ph.D