Heat-resistant and high adhesion PPCD-type double crosslinked network structure waterborne polyurethane coatings

Trimethylolpropane (TMP) as a cross-linker and KH-602, a siloxane coupling agent, were precisely grafted onto the branched chains of PPCD waterborne polyurethanes using molecular structure design. A series of waterborne polyurethanes (WPUs) were synthesized by selecting polycarbon dioxide-based polyol (PPCD) and isocyanate (IPDI) as soft and hard segments. The effects of changes in the content of TMP and KH-602 on the performance of the WPU coatings were investigated by analyzing the adhesion, mechanical, and thermal properties. The results showed that the thermal stability of the polyurethane coatings was significantly improved, and the decomposition temperature increased from 190.3 °C to 274 °C at a weight loss of 5 %. In addition, the water contact angle increased from 63.4° to 75.5° with the increase in polysiloxane content in the coating. This increase in hydrophobicity was accompanied by a significant increase in bond strength, with peel strength increasing 2.44-fold from 1.19 to 2.91 N/mm. This innovative formulation has excellent heat resistance and adhesion properties and therefore has potential for a wide range of applications in waterborne polyurethane coatings.