Development of eco-friendly, sustainable and high-solid (low-VOC) coatings have received a lot of attention due to environmental concerns and legislative issues.1,2 Hyperbranched polymers (HBPs) are suitable for low-VOC coating formulations as they exhibit a globular shape, high molecular mass at lower viscosity and high solubility.3,4 HBPs contain a highly branched structure with a large number of reactive functional end groups, which result in their versatility and multi-functional properties. HBPs can be designed based on specific needs and economically bulk synthesized. They can be further modified for useful applications and improve functionality.4-8 Polyurethanes (PUs) are termed as one of the most versatile engineering polymers due to ready availability of raw materials for their synthesis and a wide range of properties offered by them. PUs based on HBPs are suitable for high-solid, multi-functional and high-performance protective coatings.9-11 Vegetable oil-based polyols are widely used in PU formulations for being sustainable, economical, biodegradable and eco-friendly.12-14 Polyureas are formed by rapid reaction of amine and isocyanate, and exhibit a broad range of excellent coating properties with fast drying.15,16
Polyureas have a very short pot life, which either limits their application or can impact cost. To improve pot life without compromising drying time, polyaspartic (PA) polyurea coatings were developed. They were developed from polyaspartic ester polymers that contain hindered secondary aliphatic amine in the backbone, as shown in Figure 1. The structure resembles polyaspartic acid ester as seen in the red encircled part of the figure. Polyurethane-polyurea hybrid coatings exhibit better properties than polyurethane or polyurea alone.17-19