Waterborne Polyurethanes for Biodegradable Coatings

Waterborne polyurethanes (WPUs) can be formulated into coatings and adhesives, containing water as solvent or co-solvent, that form films at ambient temperature. They exhibit excellent adhesion to many surfaces, including glass and polymeric substrates. These environmentally friendly polymers are nontoxic and nonflammable, and they do not pollute the air, harm the environment, or produce wastewater. In general, polyurethanes are hydrophobic in nature and insoluble in water. Therefore, to disperse them in water, they must be structurally modified by the incorporation of ionic groups and/or nonionic hydrophilic segments into the polymer backbone. The chapter focuses on the degradation mechanisms of WPU coatings in both polyester and polyether forms. Changes in the understanding of the technical requirements and properties, along with novel approaches in creating highly degradable polyurethane, are discussed. This chapter also provides an overview of some relevant studies of biodegradable WPU coatings.