Topochemical polymerization of dumbbell-shaped diacetylene monomers: relationship between chemical structure, molecular packing structure, and gelation property.
basic_science · Level V
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- Record sourced from PubMed, PMID 28761944.
- Also identified by DOI 10.1039/c7sm01166k.
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Abstract
Herein, we have synthesized novel photopolymerizable dumbbell-shaped diacetylene liquid crystal (LC) monomers by locating a diacetylene dicarboxylic acid group at the center and chemically connecting swallow-tails, such as hydrophobic alkyl chains (abbreviated as AT<sub>3</sub>DI) and amphiphilic biphenyl mesogens (abbreviated as BP<sub>3</sub>DI), with bisamide groups. Major phase transitions of dumbbell-shaped diacetylene monomers were identified using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and Fourier transform infrared spectroscopy (FT IR). Molecular packing structures were studied based on structure-sensitive wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) analyses. Mainly, due to nanophase separations and strong intermolecular hydrogen bonding, AT<sub>3</sub>DI formed a low-ordered lamellar LC phase at room temperature. BP<sub>3</sub>DI self-assembled into highly-ordered crystal phases (K<sub>1</sub> and K<sub>2</sub>) at lower temperatures below a low-ordered lamellar LC phase, in which BP<sub>3</sub>DI were intercalated with each other to compensate the mutual volume differences. From the photopolymerization of AT<sub>3</sub>DI and BP<sub>3</sub>DI, it was realized that the topochemical reactions of dumbbell-shaped diacetylene monomers were closely related to their chemical structures as well as molecular packing structures.