Synthesis of water-borne polyurethane/hydroxyapatite chemical hybrids

A series of water-borne polyurethane (WPU)/hydroxyapatite (HAP) chemical hybrids were synthesised from polypropylene glycol (PPG), 4, 4′-methylenebis cyclohexyl isocyanate (H12MDI), dimethylbutanic acid (DMBA), 2-hydroxyethyl acrylate (HEA), and vinyltrimethoxysilane (VTMS) modified HAP. Interchain siloxane bridges were introduced among the VTMS modified HAPs via sol-gel reaction while vinyl groups of VTMS segments were UV cured with HEA termini of WPU to form interchain crosslinkings.

Improvement of thermal, mechanical, and surface properties

In this way HAP provided WPU with internal and interchain crosslinks as well as reinforcing filler to augment thermal, mechanical, and surface properties. Glass transition temperature (Tg), contact angle, hardness, water swell resistance, and tensile modulus and strength increased with HAP inclusion showing maximum at 2% beyond which the effects were less pronounced owing to the agglomeration of HAP nanoparticles in water phase.

The study is published in: Progress in Organic Coatings Volume 128, March 2019, Pages 69-74.