Insight into the Morphology, Hydrophobicity and Swelling Behavior of TiO2-Reinforced Polyurethane

In this research, the structure, morphology, hydrophobicity and swelling behaviorof a polyurethane (PU) network and its composites (PUCs) were examined. PUCs weresynthesized by the incorporation of different percentages (0.5, 1 and 2 wt.%) of unmodifiedor surface-modified TiO2 nanoparticles into a PU network based on polycaprolactone,aliphatic hyperbranched polyester and isophorone diisocyanate. In order to improveinterfacial interactions, the surface of the TiO2 nanoparticles was chemically modified withlauryl gallate. The impact of the presence and content of unmodified or surface-modifiedTiO2 nanoparticles on the cross-sectional and surface morphology, swelling behavior andhydrophobicity of the PU network was assessed by different experiments. The obtainedfindings revealed that the incorporation of TiO2 nanoparticles brought a more pronouncedirregular cross-sectional and rougher surface morphology, better microphase separation,higher values of the equilibrium swelling degree in tetrahydrofuran and toluene, andaltered water contact angles compared to the neat PU. Based on the collected results, thepractical applicability of the prepared PUCs may be in the area of protective coatings.