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A Twist Grain Boundary-like Twisted Smectic Phase in Monodisperse Poly(γ-benzyl α,l-glutamate) Produced by Recombinant DNA Techniques

He, Shi-Juang and Lee, Chin and Gido, Samuel P. and Yu, Seungju M. and Tirrell, David A. (1998) A Twist Grain Boundary-like Twisted Smectic Phase in Monodisperse Poly(γ-benzyl α,l-glutamate) Produced by Recombinant DNA Techniques. Macromolecules, 31 (26). pp. 9387-9389. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:HEm1998

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Abstract

Smectic ordering has been observed in perfectly monodisperse poly(γ-benzyl α,L-glutamate) (PBLG) which was synthesized using recombinant DNA technology. These PBLG molecules form rigid α-helical rods 11.45 nm in length. In the present study, transmission electron microscopy (TEM) and electron diffraction reveals a banded morphology with an approximately 120 nm period which provides strong evidence for helical rotation of the director field as in a cholesteric or twisted smectic. Detailed examination of the relative orientation of the banding in the morphology images and the reflections in the electron diffraction patterns, indicating interchain and intrachain correlations, leads to the conclusion that the structure observed is a twisted smectic phase. The relationship between the twist and the layering is found to be that of the twist grain boundary (TGB) phase. However, our data does not allow us to determine whether the monodisperse PBLG structure is blocky with discrete twist boundaries as in a true TGB or is a more continuously twisting structure. Thus, we will refer to the phase as TGB-like. Conventional, polydisperse PBLG is well-known to form cholesteric phases as a result of the chirality of the helical rod. The formation of a TGB-like phase in monodisperse PBLG is consistent with the superposition of a smectic-A layering resulting from the uniform rod length on the twisted texture present in the cholesteric.


Item Type:Article
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http://dx.doi.org/10.1021/ma981286jDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma981286jPublisherArticle
ORCID:
AuthorORCID
Tirrell, David A.0000-0003-3175-4596
Additional Information:Copyright © 1998 American Chemical Society. Received August 13, 1998; Revised Manuscript Received October 26, 1998. Publication Date (Web): December 5, 1998. Funding from the NSF Division of Materials Research, Polymers Program (S. P. Gido CAREER award, DMR-9624306) is gratefully acknowledged. Funding was also provided by the NSF Material Research Science and Engineering Center (MRSEC) at the University of Massachusetts Amherst. We would like to thank E. D. T. Atkins and R. Valluzzi for useful discussions.
Funders:
Funding AgencyGrant Number
NSFDMR-9624306
Issue or Number:26
Record Number:CaltechAUTHORS:HEm1998
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:HEm1998
Official Citation:A Twist Grain Boundary-like Twisted Smectic Phase in Monodisperse Poly(γ-benzyl α,l-glutamate) Produced by Recombinant DNA Techniques Shi-Juang He, Chin Lee, Samuel P. Gido, Seungju M. Yu, and David A. Tirrell Macromolecules 1998 31 (26), 9387-9389
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53390
Collection:CaltechAUTHORS
Deposited By: Anne Hormann
Deposited On:06 Feb 2015 05:00
Last Modified:03 Oct 2019 07:49

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