Effect of the linking structure of nonlinear optical side groups on the phase behavior of an aromatic polyester backbone

Maeng Eun Lee, Seayeal Seong, Kyoung Tai No, O. Pil Kwon, Suck Hyun Lee

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Abstract

The phase behavior of poly(p-phenylene terephthalate)s (PPT) with pendant side groups, N-(4-nitrophenyl)-ethylaminoethanol (NPE) and N-(4-nitrophenyl)-L- prolinol (NPP) has been studied by using differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), and second harmonic generation (SHG). PPT-NPE showed a layered liquid crystalline morphology while PPT-NPP showed a completely amorphous structure. Comprehensive or shear stress applied on the polymer melt surface at 210 °C induced a more prominent layered structure of PPT-NPE whereas the amorphous structure of PPT-NPP remained unchanged under the stress. In order to understand this phase difference in terms of the repeat structure, we attempted theoretical ab initio Hartree-Fock and DFT calculations for the monomers and molecular dynamics for the bulk state. The result indicated that molecular configurations are a good way of microspically understanding the phases of rigid backbone polymers with functional side groups: The NPT (constant particle number, pressure, and temperature) simulation data at 210 °C agree qualitatively with the experimental data and the difference PPT-NPE and PPT-NPP could be understood using rotational energy barrier, steric hindrance and inter-chain interaction. X-ray diffractometer (XRD) simulation patterns for the oligomers are also in qualitative agreement with the experimental WAXS data and the structural parameters of stacks of PPT-NPE chains are estimated to be layer distance (4.6 Å), backbone distance (21.5 Å), and side distance (12 Å).

Original languageEnglish
Pages (from-to)265-272
Number of pages8
JournalMacromolecular Theory and Simulations
Volume13
Issue number3
DOIs
Publication statusPublished - 2004 Apr 15

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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