Study on the surface properties and thermal stability of polysiloxane-based polyurethane elastomers with aliphatic and aromatic diisocyanate structures

A series of polysiloxane-based polyurethane elastomers with aliphatic and aromatic diisocyanate structures are prepared using a two-step polymerization method. First, tolylene diisocyanate (TDI); dicyclohexylmethane 4,4′-diisocyanate (H₁₂MDI); and hexamethylene diisocyanate (HDI) separately react with polycarbonate diol (PCDL) to produce polyurethane prepolymer, and furthermore, polysiloxane (PDMS) is added to the system to produce different polymers. The effect of different diisocyanate structures on mechanical properties, thermal stability, surface topography, and hydrophobic properties are explored. The results show that when the mass loss is higher than 50% during thermal decomposition, TDIPU exhibits relatively excellent thermal stability, which may be caused by the exposure of the silicone inside the polymer. HDIPU shows high hydrophobicity and low surface free energy, which is mainly related to a large amount of Si enriched on the surface. These differences are mainly caused by different molecular structures.