Surface, structural, and thermal properties of polydimethylsiloxane-based polyurethanes and their blends with thermoplastic polyurethane elastomer.

Two series of polyurethanes (PUR) were synthesized in a one-step procedure, using a polydimethylsiloxane (M_n ~ 2000 g/mol) in different molar ratios (10, 15, and 20 mol%) as soft segments, hexamethylene diisocyanate, and isophorone diisocyanate as a part of hard segments. Butane-1,4-diol was used as a chain extender in polyurethane synthesis. Obtained PURs were thoroughly studied and used for the preparation of blends with commercial thermoplastic polyurethane elastomer. In combination with commercial PUR, some synthesized samples behave as plasticizers, increasing the breaking strain and decreasing the Young's modulus values. Blends with commercial PUR and 10 wt% of sample synthesized using an isophorone diisocyanate have shown an increase in strain values, but also values of break and Young's modulus, resulting in materials with fully improved mechanical properties, and mostly higher hydrophobicity. The greatest values of breaking strain (1712.72%) and max strain (1637.09%) were recorded for the blend which contains 10 wt% of PUR sample based on isophorone diisocyanate and 20 mol% of polydimethylsiloxane, while blend which contains 10 wt% of PUR sample synthesized using isophorone diisocyanate and 10 mol% of polydimethylsiloxane has the greatest value of Young's modulus (3.55 N/mm²). Prepared blends possess a lower surface tension values in comparison with the commercial PUR. The lowest value of surface tension (13.23 mN/m) was recorded for blend which contains 30 wt% of PUR sample synthesized using the isophorone diisocyanate and 20 mol% of polydimethylsiloxane. [ABSTRACT FROM AUTHOR]