Paper
Side-Chain Liquid-Crystalline Polysiloxanes via Anionic Polymerization: (n-Undecyloxy)arenecarboxylic Acid Mesogens Linked to Poly(dimethylsiloxane-co-methylvinylsiloxane)
Published Jan 27, 1997 · M. Hempenius, R. Lammertink, G. Vancso
Macromolecules
29
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Abstract
A novel, anionic route to well-defined side-chain liquid-crystalline polysiloxanes is described. The usual cationic approach to these polymers leads to polydisperse materials with uncontrolled microstructures. Ring-opening polymerization of pentamethylvinylcyclotrisiloxane yielded a poly(dimethylsiloxane-co-methylvinylsiloxane) with a low polydispersity (M w /M n = 1.16), a controlled molar mass, and a uniform distribution of pendant vinyl groups along the chain. Vinyl-containing mesogenic molecules could be attached to the polysiloxane vinyl groups in a two-step hydrosilylation reaction by means of the coupling agent 1,1,3,3-tetramethyldisiloxane, yielding polymers with regularly spaced side groups. The flexible disiloxane link increases the mobility of the mesogenic moieties. In this study, 4-(n-undecyloxy)benzoic acid and the novel side group 4'-(n-undecyloxy)-4-biphenylcarboxylic acid were used as mesogens. The thermal behavior of the side-chain liquid-crystalline polymers was investigated by means of differential scanning calorimetry and optical microscopy.
This study presents a novel anionic route to well-defined side-chain liquid-crystalline polysiloxanes with controlled microstructures, offering potential applications in electronics and pharmaceuticals.
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