Synthesis and Anisotropic Behavior of New Ladderlike Polysilsesquioxanes with Side-on and End-on Fixed NLO Chromophores

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Abstract
This report deals with a new kind of ladderlike polysilsesquioxanes with nonlinear optical (NLO) chromophores which are laterally (side-on) or terminally (end-on) fixed on the ladder-like macromolecular backbones. These new functionalized ladderlike polysiloxanes were synthesized via hydrosilylation reaction of a series of diphenyl acetylene (tolan) derivatives (for side-on fixed) or vinyl-terminated diphenylethylene (stilbene) derivatives (for end-on fixed) with ladderlike polyhydrosilsesquioxane [H-T] or its copolymers [PH-T]. The anisotropic behavior of the mesogenic polymers were studied by IR dichroism, temperature-variable X-ray diffraction and optical polarized microscopy. The “Rowboat model” for side-on fixed liquid crystalline polysilsesquioxane was confirmed by IR dichroism and X-ray diffraction observations.