Get access

Influence of molecular weight on the phase behaviors of comb-like polymers with long n-alkyl side chains based on mesogen-jacketed liquid crystalline polymers

Authors

  • Sheng Chen,

    1. Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, and Universities of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
    Search for more papers by this author
  • Hai-bin Luo,

    1. Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, and Universities of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
    Search for more papers by this author
  • He-Lou Xie,

    1. Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, and Universities of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
    Search for more papers by this author
  • Hai-Liang Zhang

    Corresponding author
    1. Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, and Universities of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
    • Key Laboratory of Polymeric Materials and Application Technology of Hunan Province, College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, China
    Search for more papers by this author

Abstract

A series of comb-like polymers, poly{2,5-bis[(4-octadecyloxyphenyl)oxycarbonyl]-styrenes{ (P-OC18s) with different molecular weights (Mn) and low molecular weight distributions have been successfully synthesized via atom transfer radical polymerization. The phase behaviors have been investigated by a combination of techniques including differential scanning calorimetry, polarized optical microscopy, wide-angle X-ray diffraction, and temperature-variable FTIR spectroscopy. One hand, phase behaviors of the alkyl tails were strongly influenced by the mesogens of polymers, leading to the poor packing of the alkyl tails and the low melting. The other hand, the liquid crystalline phase structures of polymers were found to be strongly Mn dependent. The samples with Mn ≤ 4.6 × 104 formed a smectic phase in low temperature and an isotropic phase in high temperature. The samples with Mn ≥ 5.2 × 104 displayed a reentrant isotropic phase, which was separating the smectic phase and columnar nematic phase. Meantime, the experiment results showed that the glass temperature and the transition temperature from smectic phase to isotropic phase both slightly increased with the increase of MnS; however, the transition temperature from isotropic phase to columnar phase sharply decreased with the MnS improved. The reappearance of isotropic phase is due to the competing between the driving force of the enthalpy and the driving force of the entropy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Get access to the full text of this article

Ancillary