Preparation of ordered and crosslinked films from liquid crystalline p‐vinylphenoxy‐based monomers

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Abstract
The synthesis of the following monofunctional and bifunctional liquid crystalline p‐vinylphenoxy‐based monomers is described: 4‐methoxyphenyl 4‐[11‐(4‐vinylphenoxy)‐undecyloxy]benzoate (1), 4‐cyanophenyl 4‐[11‐(4‐vinylphenoxy)undecyloxy]benzoate (2) and 3‐(4‐vinylphenoxy)propyl 4‐{4‐[11‐(4‐vinylphenoxy)undecyloxy]benzoyloxy}benzoate (3). Both free radical and cationic polymerization of the monofunctional monomers 1 and 2 yielded side‐chain liquid crystalline polymers exhibiting smectic A mesomorphism. The polymers exhibited high molar masses (Mn = 40000 – 100000 g/mol) and relatively narrow molar mass distributions (Mw/Mn between 1.5 and 3). Ordered thin films were prepared by in‐situ photopolymerization of monomers 1, 2 and 3 oriented in their nematic mesophases. Thin films of a thermally stabilized ordered side‐chain liquid crystalline polymer were prepared by copolymerization of the monofunctional monomer 1 and the bifunctional monomer 3, the latter present in low concentration. The films regained orientation when cooled down from temperatures above the isotropization point (137°C) as evidenced by polarized FT‐Raman measurements.