Abstract
The dynamic moduli of side-group liquid-crystalline polymers (SG-LCPs) having methacrylate backbone, hexamethylene spacer, and phenyl benzoate mesogens are characterized as a function of molecular weight in the isotropic, nematic, and smectic phases. Molar mass was varied from 3 × 105 to 3 × 106 g/mol, corresponding to the range where the onset of entanglement is observed in the isotropic phase (approximately 1–10Me,iso). Nematic order produces a profound change in the dynamics of the entangled SG-LPCs relative to the isotropic phase; however, this effect is absent in the unentangled SG-LCPs. Oscillatory shear with large amplitude (γ0 ≥ 40%) is effective in inducing macroscopic alignment in the nematic phase for all the SG-LCPs studied. Smectic order increases the elastic character of the fluid, but its incremental effect in a system that is entangled is relatively small. Large-amplitude shearing can be used to alter the microstructure in the smectic liquid: shearing the smectic phase produces a decrease in modulus, whereas shearing in the nematic phase followed by cooling into the smectic phase produces an increase in modulus.
Original language | English (US) |
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Pages (from-to) | 3521-3530 |
Number of pages | 10 |
Journal | Macromolecules |
Volume | 28 |
Issue number | 10 |
DOIs | |
State | Published - May 1 1995 |
Externally published | Yes |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry