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Title: Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials

Abstract

This work details an integrated investigation of liquid crystal (LC) oligomers that combines experiments and molecular dynamics simulations to obtain a detailed understanding of the molecular structure of LC oligomers and the mechanism underlying their phase transition temperatures. We synthesized and characterized a series of LC oligomers prepared from different lengths of methylene spacers in the reactive LC monomers and n-alkylamine chain extenders via the aza-Michael addition reaction. In parallel, we performed isothermal–isobaric ( NPT) ensemble coarse-grained molecular dynamics (CG-MD) simulation of analogue mesogens that are connected to flexible spacers and extenders at varying temperatures, spacer lengths, and extender lengths. This approach allowed the effect of length in the flexible spacer as well as in the chain extender on the nematic–isotropic transition temperature ( T ni) to be determined. The results showed that increasing the length of the extender decreases T ni for LC oligomers and amplifies the decrease of T ni in LC oligomers when the spacer length is short. We infer that the combination of spacer and extender changes the shape anisotropy of LC oligomers, changing the packing behavior of constituent mesogens, thus affecting their ability to transition from the isotropic to the nematic phase. Here, the detailedmore » molecular structure–property relationships formulated enable prescribing design rules for LC oligomers geared toward molecularly engineered shape changing materials.« less

Authors:
 [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]
  1. Pusan National Univ., Busan (Korea)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1560464
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Name: Macromolecules; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Guo, Yuanhang, Lee, Jieun, Son, Jinha, Ahn, Suk-kyun, Carrillo, Jan-Michael Y., and Sumpter, Bobby G. Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials. United States: N. p., 2019. Web. doi:10.1021/acs.macromol.9b01218.
Guo, Yuanhang, Lee, Jieun, Son, Jinha, Ahn, Suk-kyun, Carrillo, Jan-Michael Y., & Sumpter, Bobby G. Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials. United States. doi:10.1021/acs.macromol.9b01218.
Guo, Yuanhang, Lee, Jieun, Son, Jinha, Ahn, Suk-kyun, Carrillo, Jan-Michael Y., and Sumpter, Bobby G. Tue . "Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials". United States. doi:10.1021/acs.macromol.9b01218.
@article{osti_1560464,
title = {Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials},
author = {Guo, Yuanhang and Lee, Jieun and Son, Jinha and Ahn, Suk-kyun and Carrillo, Jan-Michael Y. and Sumpter, Bobby G.},
abstractNote = {This work details an integrated investigation of liquid crystal (LC) oligomers that combines experiments and molecular dynamics simulations to obtain a detailed understanding of the molecular structure of LC oligomers and the mechanism underlying their phase transition temperatures. We synthesized and characterized a series of LC oligomers prepared from different lengths of methylene spacers in the reactive LC monomers and n-alkylamine chain extenders via the aza-Michael addition reaction. In parallel, we performed isothermal–isobaric (NPT) ensemble coarse-grained molecular dynamics (CG-MD) simulation of analogue mesogens that are connected to flexible spacers and extenders at varying temperatures, spacer lengths, and extender lengths. This approach allowed the effect of length in the flexible spacer as well as in the chain extender on the nematic–isotropic transition temperature (Tni) to be determined. The results showed that increasing the length of the extender decreases Tni for LC oligomers and amplifies the decrease of Tni in LC oligomers when the spacer length is short. We infer that the combination of spacer and extender changes the shape anisotropy of LC oligomers, changing the packing behavior of constituent mesogens, thus affecting their ability to transition from the isotropic to the nematic phase. Here, the detailed molecular structure–property relationships formulated enable prescribing design rules for LC oligomers geared toward molecularly engineered shape changing materials.},
doi = {10.1021/acs.macromol.9b01218},
journal = {Macromolecules},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {9}
}

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This content will become publicly available on September 3, 2020
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