Helical single-lamellar crystals thermotropically formed in a synthetic nonracemic chiral main-chain polyester

Christopher Y. Li, Donghang Yan, Stephen Z. D. Cheng, Feng Bai, Jason J. Ge, Bret H. Calhoun, Tianbai He, Liang-Chy Chien, Frank W. Harris, and Bernard Lotz
Phys. Rev. B 60, 12675 – Published 1 November 1999
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Abstract

Phase structures and transformation mechanisms of nonracemic chiral biological and synthetic polymers are fundamentally important topics in understanding their macroscopic responses in different environments. It has been known for many years that helical structures and morphologies can exist in low-ordered chiral liquid crystalline (LC) phases. However, when the chiral liquid crystals form highly ordered smectic liquid crystal phases, the helical morphology is suppressed due to the crystallization process. A double-twisted morphology has been observed in many liquid crystalline biopolymers such as dinoflaggellate chromosomes (in Prorocentrum micans) in an in vivo arrangement. Helical crystals grown from solution have been reported in the case of Bombyx mori silk fibroin crystals having the β modification. This study describes a synthetic nonracemic chiral main-chain LC polyester that is able to thermotropically form helical single lamellar crystals. Flat single lamellar crystals can also be observed under the same crystallization condition. Moreover, flat and helical lamellae can coexist in one single lamellar crystal, within which one form can smoothly transform to the other. Both of these crystals possess the same structure, although translational symmetry is broken in the helical crystals. The polymer chain folding direction in both flat and helical lamellar crystals is determined to be identical, and it is always along the long axis of the lamellae. This finding provides an opportunity to study the chirality effect on phase structure, morphology, and transformation in condensed states of chiral materials.

  • Received 25 March 1999

DOI:https://doi.org/10.1103/PhysRevB.60.12675

©1999 American Physical Society

Authors & Affiliations

Christopher Y. Li

  • The Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909

Donghang Yan

  • Polymer Physics Laboratory, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China

Stephen Z. D. Cheng*, Feng Bai, Jason J. Ge, and Bret H. Calhoun

  • The Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909

Tianbai He

  • Polymer Physics Laboratory, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China

Liang-Chy Chien

  • Liquid Crystal Institute, Kent State University, Kent, Ohio 44010-0001

Frank W. Harris

  • The Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909

Bernard Lotz

  • Institute Charles Sadron, 6 Rue Boussingault, Strasbourg 67083, France

  • *Author to whom correspondence should be addressed. Electronic address: cheng@polymer.uakron.edu

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Vol. 60, Iss. 18 — 1 November 1999

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