In this research, the structure, morphology, hydrophobicity and swelling behavior of a polyurethane (PU) network and its composites (PUCs) were examined. PUCs were synthesized by the incorporation of different percentages (0.5, 1 and 2 wt.%) of unmodified or surface-modified TiO2 nanoparticles into a PU network based on polycaprolactone, aliphatic hyperbranched polyester and isophorone diisocyanate. In order to improve interfacial interactions, the surface of the TiO2 nanoparticles was chemically modified with lauryl gallate. The impact of the presence and content of unmodified or surface-modified TiO2 nanoparticles on the cross-sectional and surface morphology, swelling behavior and hydrophobicity of the PU network was assessed by different experiments. The obtained findings revealed that the incorporation of TiO2 nanoparticles brought a more pronounced irregular cross-sectional and rougher surface morphology, better microphase separation, higher values of the equilibrium swelling degree in tetrahydrofuran and toluene, and altered water contact angles compared to the neat PU. Based on the collected results, the practical applicability of the prepared PUCs may be in the area of protective coatings.
Keywords: polyurethane composites; structure; morphology; titanium dioxide nanoparticles; swelling behavior; hydrophobicity