Implications for Auxetic Response in Liquid Crystalline Polymers: X‐Ray Scattering and Space‐Filling Molecular Modeling

@article{Verma2020ImplicationsFA,
  title={Implications for Auxetic Response in Liquid Crystalline Polymers: X‐Ray Scattering and Space‐Filling Molecular Modeling},
  author={Prateek Verma and Chaobin He and Anselm C. Griffin},
  journal={physica status solidi (b)},
  year={2020},
  volume={257}
}
Five transverse rod (TR)‐containing main‐chain liquid crystalline polymers (LCPs) are examined in both the powder and fiber forms by wide angle X‐ray diffraction. Data from the diffraction experiments are consistent with the site‐connectivity‐driven TR‐reorientation mechanism for intrinsic auxetic character in these macromolecules. Shifts in peak maxima, intensity distributions in the interchain interaction region, and calculated volume increase accompanying fiber formation are all in line with… 
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References

SHOWING 1-10 OF 44 REFERENCES

Toward molecular auxetics: Main chain liquid crystalline polymers consisting of laterally attached para‐quaterphenyls

Polymers containing para‐quaterphenyl rods laterally attached to the polymer main chain have been synthesized. The molecular design choices which led to use of the quaterphenyl rod to achieve auxetic

Relationship between interchain spacing of amorphous polymers and blend miscibility as determined by wide‐angle X‐ray scattering

The average molecular interchain spacing (〈R〉) in Angstroms for amorphous polymers was calculated from the strong maximum in the wide-angle X-ray scattering (WAXS) diffraction scan using established

X‐ray scattering from amorphous acrylate and methacrylate polymers: Evidence of local order

X-ray scattering patterns from amorphous polymers frequently contain halos corresponding to distances significantly greater than that of van der Waals packing of carbon atoms. Regularities in the

Coincident molecular auxeticity and negative order parameter in a liquid crystal elastomer

The authors demonstrate auxeticity in a non-porous liquid crystal elastomer overcoming porosity related weakening of the material and opening a pathway to designed molecular auxetic materials.

Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (molecular mechanics) have been performed to investigate the mechanism for auxetic

Mesogenic polymers. III. Thermal properties and synthesis of three homologous series of thermotropic liquid crystalline ``backbone'' polyesters

Details of the thermal behavior, including transition temperatures, transition heats and transition entropies, are reported for three series of nematic liquid-crystalline “backbone” polyesters having

Modelling of auxetic networked polymers built from calix[4]arene building blocks

Auxetic materials (i.e. materials with a negative Poisson's ratio) expand laterally when stretched and become thinner when compressed. This unusual yet very useful property arises from the way by

Soft Elasticity in Main Chain Liquid Crystal Elastomers

Main chain liquid crystal elastomers exhibit several interesting phenomena, such as three different regimes of elastic response, unconventional stress-strain relationship in one of these regimes, and

A Liquid Crystalline Elastomer with a p‐Pentaphenyl Transverse Rod Laterally Attached to the Main Chain

An LCE with a p-pentaphenyl transverse rod in the main chain was synthesized, in which the rod can be oriented parallel or normal to the main chain under uniaxial tension. DSC and WAXD studies

Dynamic simulations of potentially auxetic liquid-crystalline polymers incorporating swivelling mesogens

Dynamic simulations under stress were carried out on a series of main-chain polymers containing two types of mesogen. One mesogen is orientated in-line with the chain (end-to-end) and the second