Study on thermal stability of polyurethane-urea based on polysiloxane and polycaprolactone diols

Different grades of segmented polyurethane-urea were synthesized through two-step solution polymerization of polydimethylsiloxane (PDMS) and polycaprolactone (PCL) polyols with methylene diphenyl diisocyanate (MDI) and mixture of 1,4-buthanediol and 4,4-methylene bis (3-chloro 2,6-diethylaniline) in toluene/tetra-hydrofuran media. Structural characterization of the synthesized samples was conducted using Fourier transform infra-red spectroscopy. X-ray diffraction, dynamic mechanical thermal analysis, thermal gravimetric analysis, and differential scanning calorimetry techniques were utilized to assess material characteristics. The results showed a relationship between PDMS content and thermal stability, morphology and mechanical properties of the urethane-urea samples. Onset degradation temperature was increased by increasing the PDMS content in the polyurethane backbone where the crystallinity was varied versus PDMS content. Strong interaction established between hard and soft segments resulted in a positive shift in PCL glass transition temperature. Tracking E′, E″ and damping factor in DMTA measurements confirmed the two-phase morphology. Hydrophobicity of polymer surfaces was traced by contact angle measurement.