Chemical hybridization of waterborne polyurethane with β-cyclodextrin by sol-gel reaction

A series of waterborne polyurethane (WPU)/β-cyclodextrin (β-CD) chemical hybrids were synthesized from polypropylene glycol (PPG400), dicyclohexylmethane-4,4′-diisocyanate (H12MDI), dimethylol butanoic acid (DMBA), 3-isocyanatepropyltriethoxysilane (ICPTES), and β-CD. The ICPTES-terminated WPU prepolymers were chain extended via a sol-gel reaction by using β-CD as a biodegradable multifunctional crosslinker at various β-CD equivalence ratios (ICPTES:β-CD = 1:0.5, 1:1, 1:1.5, and 1:2). The thermal, mechanical, and surface properties of the WPU/β-CD dispersion cast film were investigated, with biodegradation experiments carried out in α-amylase enzyme solution. The glass transition temperature (Tg), particle size, Young's modulus, and hardness of the dispersion cast film increased up to an equivalence ratio of 1:1.5 owing to effective migration of β-CD molecules into WPU and crosslinking via the sol-gel reaction. However, at higher ratios, most of these parameters decreased owing to aggregation of β-CD.