Preparation of Polyurethane/Nano-TiO₂ Hybrid Materials Containing Alkyl Side Chains in Soft Segments

Two well-defined comb-like polyester diols (GS) with C-18 side chains were synthesized by reacting glyceryl monostearate (GMS) with succinic anhydride. NCO-terminated polyurethane prepolymers (PUGS) with C-18 side chains in soft segment structure were synthesized from diphenylmethane diisocyanate (MDI), 1,4-butanediol (BDO) and GS. Then polyurethane hybrid materials (PUGS-Ti) were further prepared by mixing with nano-TiO₂. The structures of GS and PUGS were characterized by ¹H-NMR and FT-IR. The crystallization behavior, surface morphology and surface contact angle of the prepared PUGS and its hybrid material were characterized by DSC, WAXD, SEM, AFM and water contact angle measurements. The effects of alkyl side chain content and the amount of TiO₂ on the surface properties of PUGS and its hybrid material were investigated. Results showed that the introduction of non-polar alkyl side chains into the polyurethane could significantly reduce the surface energy and improve the contact angles of water on the surface. In PUGS-Ti, the surface energy of the materials could be effectively adjusted to achieve superhydrophobicity of the surface by adjusting the content of soft segments (the number of alkyl side chains) and the amount of TiO₂ in the structure.