Dithiols as Liquid Crystalline Building Blocks for Smart Polymers via Thiol–yne Click Chemistry

Year: 2021

Authors: Lupi F., Martella D., Nocentini S., Antonioli D., Laus M., Wiersma D.S., Parmeggiani, C.

Autors Affiliation: Ist Nazl Ott CNR INO, I-50019 Sesto Fiorentino, Italy; European Lab Nonlinear Spect Lens, I-50019 Sesto Fiorentino, Italy; Ist Nazl Ric Metrol INRiM, I-10135 Turin, Italy; Univ Piemonte Orientale Avogadro, Dipartimento Sci & Innovaz Tecnol DISIT, I-15121 Alessandria, Italy; Univ Florence, Phys & Astron Dept, I-50019 Sesto Fiorentino, Italy; Univ Florence, Dept Chem Ugo Schiff, I-50019 Sesto Fiorentino, Italy.

Abstract: Since 30 years, liquid crystalline elastomers (LCEs) have been attracting the attention of many researchers thanks to their anisotropic molecular structure which allows them to build up artificial muscles. Possible applications span from soft robotics to biomedical or tunable optical devices.
The power of thiol−yne click chemistry was recently demonstrated in the preparation of smart polymers, in particular LCEs, in which the mesogenic units are incorporated both in the main-chain and as pendant groups. To enrich the library of available LCE materials, in this work, several liquid crystalline dithiols and alkynes have been synthesized and copolymerized to obtain elastomers with different thermomechanical properties. The architecture of the main chain was found to play a prominent role in modulating the clearing point in a range of 60 °C, whereas only a minor contribution is given by the mesogens in the side chain. On the other hand, the mechanical response resulted highly sensitive to fine details of the side-chain structure. Accordingly, the present study not only improves the basic understanding of the chemical−physical properties of LCEs but paves the way to the preparation of multicomponent actuators able to deform in different temperature ranges, thus ultimately leading to complex soft robotic operations.

Journal/Review: ACS APPLIED POLYMER MATERIALS

Volume: 3 (3)      Pages from: 1602  to: 1609

More Information: Financial support from the Ente Cassa di Risparmio di Firenze (grant 2017/0713 and 2020/1583) is acknowledged.
KeyWords: thiol−yne click chemistry liquid crystalline elastomers liquid crystalline thiols smart materials thermoresponsive polymers
DOI: 10.1021/acsapm.0c01423

Citations: 7
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