Title: Effects of tacticity and chiral center-to-dipole distance on mesogen-free liquid crystalline self-assembly of sulfonyl-containing comb-like polymers

Abstract

In this report, new approaches were implemented to achieve novel ferroelectric liquid crystalline self-assembly in mesogen-free comb-like isotactic polyoxypropylenes (iPOPs) bearing mono- or di-sulfonyl groups, which have potential to exhibit high spontaneous polarization for applications in advanced electronic devices. iPOPs with n-alkylsulfonylpentylthioether side chains (iPOP-SC₅SO₂C_n, where C_n is the alkyl tail with n being either 12 or 8) were prepared via a post-polymerization substitution reaction from isotactic poly[(R)-(–)-epichlorohydrin]. Here, the effects of main-chain tacticity, chiral center-to-dipole distance, number of sulfonyl dipoles per side chain, and n-alkyl tail length on the liquid crystalline self-assembly behavior were investigated by comparing iPOPs with their atactic counterparts. First, when the sulfonyl dipole was placed far away from the chiral center in iPOP-SC₅SO₂C_n compared with our previously reported isotactic polyethers with n-alkylsulfonyl side chains (iPOP-SO₂C_n), the dipole–dipole interactions among the side chains decreased, which led to more liquid crystalline phases. Smectic E (SmE) and A (SmA) phases were observed after crystal melting; however, the main-chain chiral center was found to have an insignificant effect on the liquid crystalline assembly when compared to the atactic samples. Second, the longer C_n tails increased the transition temperatures as a result of stronger van der Waals interactions. Third, aftermore » the thioether linkage in the side chain was oxidized into the sulfonyl group, the chiral center–dipole and dipole–dipole interactions in the resultant polymers (i.e., iPOP-SO₂C₅SO₂C_n) enhanced. As a result, the liquid crystalline phase transitions (i.e., crystal → SmE → SmA → I) were pushed to higher temperatures. The knowledge gained in this study will help us further design and achieve the ferroelectric smectic C* phase in mesogen-free comb-like sulfonylated liquid crystalline polymers.« less

Authors:

Bohannon, Caleb A. ^[1]; Kwok, Man-Hin ^[2]; Li, Ruipeng ^[3]; Zhu, Lei  ^[2];

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• Search DOE PAGES for ORCID "0000-0001-6570-9123"

Zhao, Bin  ^[1]

• Search DOE PAGES for author "Zhao, Bin"
• Search DOE PAGES for ORCID "0000-0001-5505-9390"

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+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States)
2. Case Western Reserve Univ., Cleveland, OH (United States)
3. Brookhaven National Lab. (BNL), Upton, NY (United States)

Publication Date:

Mon Mar 30 00:00:00 EDT 2020

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States); Case Western Reserve Univ., Cleveland, OH (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1633601

Alternate Identifier(s):

OSTI ID: 1608500; OSTI ID: 1899875

Report Number(s):

BNL-216041-2020-JAAM
Journal ID: ISSN 1759-9954; PCOHC2

Grant/Contract Number:  

SC0012704; SC0018075

Resource Type:

Accepted Manuscript

Journal Name:

Polymer Chemistry

Additional Journal Information:

Journal Volume: 11; Journal Issue: 17; Journal ID: ISSN 1759-9954

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Mesogen-free; comb-like polymers; chirality effect; sulfonyl dipole; polyoxypropylenes