Herein, we describe structure-property relations of side-chain liquid crystalline polymers (SCLCPs) where varied flexible methylene spacer (n=4, 5, 9, 10 and 15) decouples motion between polynorbornene main-chains and cholesteryl side-chains. Upon change of the length of flexible methylene spacer, the SCLCPs exhibit different smectic A (SmA) polymorphism from non-interdigitated bilayers (n=4, 5), partially interdigitated mixed layers (n=9, 10) and highly interdigitated single layers (n=15) as determined by differential scanning calorimetry (DSC) and X-ray diffraction (XRD).  Interestingly, the cholesteric phases exclusively appear in PNBCh-9 and 10. The presence of cholesteric phases and their selective light reflection properties are characterized by polarized optical microscopy (POM), transmission electron microscopy (TEM), and UV-VIS. The characteristic oily-streak textures of cholesteric phases are observed by POM, and the helical pitch of cholesteric layers are determined by TEM and UV-VIS. Moreover, X-ray scattering measurements with and without temperature control are further performed to examine mesomorphic structure evolution. By comparing the mesomorphic structures in this series of SCLC homopolymers, both extent of mesogen interdigitation and motional decoupling between backbone and mesogenic side-chains are found to play a critical role in the development of cholesteric mesophase

Effect of interdigitation and motional decoupling on mesophase changes in side-chain liquid crystalline polymers bearing cholesterol

244th National Meeting (2012)

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