Liquid crystalline polyurethanes modified by Trisilanolisobutyl-POSS

Abstract A series of liquid crystalline polyurethanes based on 4,4′-bis(hydroxyhexoxy)biphenyl moieties and modified by Trisilanolisobutyl-POSS (TRIS-POSS) was synthesized via a polyaddition reaction. ATR-FTIR confirmed introduction of POSS moieties into the macrochain. Formation of liquid crystalline phases along with higher melting and crystallization temperatures due to the addition of the POSS moieties has been observed by Differential Scanning Calorimetry (DSC) and Polarized Optic Microscopy (POM). The influence of the POSS on the improvement of thermal stability and char residue after degradation is also discussed. Influence of the POSS particles on glass transition was found to be relevant for high mesogenic unit load. Morphological investigations by Scanning Electron Microscopy showed different distribution of the POSS nanoparticles for each examined matrix and absence of POSS originated agglomerates which was also confirmed by X-ray diffraction technique. Reinforcement effect of the POSS on mechanical properties was also investigated. Mechanically induced anisotropy was hypothesized to be one of the factor responsible for improved tensile strength at high strain.