Increasing the Hydrophobicity of Hybrid Poly(propylene glycol)-Based Polyhydroxyurethanes by Capping with Hydrophobic Diamine

Abstract

Hydrophobicity of hybrid polyhydroxyurethane (HPHU), via sol/gel curing of a PHU made from diglycerol dicarbonate (DGC) and a poly(propylene glycol) (PPG)-based diamine, is increased by reacting the carbonate-terminated PHU with diamines based on poly(dimethylsiloxane) (PDMS) and the fatty acid-derived Priamine 1074. The modified PHUs were end-capped with silane moisture-curing agents, and swelling of the HPHUs was studied in water and other solvents over 1 week. These films exhibited a drop in the water swelling index (4%) compared to the original poly(DGC-PPG) HPHUs (75%). The PDMS-modified HPHU has a dominant PDMS phase, due to its comparatively longer chain length relative to the PHU, thereby increasing water repellency. Besides an increase in hydrophobicity, the Priamine 1074-modified HPHU revealed a higher storage modulus that is at least 12 times higher than that of the original films. Consequently, Priamine 1074 is regarded as a promising biobased reactive additive when formulating hydrophobic PHU resins.