Random Liquid Crystalline Copolymers Consisting of Prolate and Oblate Liquid Crystal Monomers

Abstract

Interactions between side chains of polymers have been utilized to tune the thermal and mechanical properties of polymeric materials. In liquid crystal (LC) elastomers (LCEs), previous studies have demonstrated that the configuration of LC monomers, specifically oblate or prolate, determines the direction of macroscopic material deformations relative to the orientational ordering of the LC functional groups. However, the effects of the copolymerization between different configurations of LC monomers on the phase behaviors and thermomechanical properties of LCEs have not been explored. Here, we reveal that statistically random copolymers of LC monomers with different configurations destabilize the orientational order of the LC functional groups, whereas the random insertion of LC monomers with the same configuration preserves the packing of the constituent mesogenic functional groups. We further demonstrate how this fundamental understanding can be applied to control both the direction and magnitude of the thermally triggered mechanical deformations of LC copolymer networks.

Degree of Orientation in Liquid Crystalline Elastomers Defines the Magnitude and Rate of Actuation

“…The thermomechanical response of LCEs is directional when the liquid crystalline orientation is aligned. − Liquid crystallinity within LCEs is based on the organization of molecular units (e.g., mesogens) via intermolecular interactions between the typically aromatic units in the segment . Aligned LCEs exhibit large and directional stimuli-response, associated with disruption of this orientational order. , Numerous reports detail thermotropic actuation of LCEs. ,− …”

Positional Isomerism-Mediated Copolymerization Realizing the Continuous Luminescence Color-Tuning of Liquid-Crystalline Polymers

“…To address the abovementioned issue, it is of significance to explore a new method for modulating emission colors based on the well-defined LC structure as a slight change in packing structure may give rise to unpredictable color alteration. − Random copolymerization of mesogens of different kinds has been demonstrated to be a simple yet effective synthetic method that can be used to tailor the LC properties. − Although copolymerization of different color-coded fluorophores has achieved variable emissions, − it is still rather difficult to achieve in ordered LC systems. The immiscibility of these common fluorophores may induce certain nanoscale phase separation or packing structural uncertainty due to the large differences in molecular dimension, geometry, etc. , Thus, it is desirable to explore suitable mesogenic fluorophore pairs, which should not only exhibit substantially different emissions but also have similar molecular architectures to facilitate mutual interaction and homogeneous coassembly into defined LC structures.…”

Synthesis and Phase Behavior of (Semifluorinated Alkane)‐Based Side‐Chain Liquid Crystalline Copolymers

“…Liquid crystalline (LC) polymer features great properties of ordered nanostructure, [ 1,2 ] efficient response to external stimuli, [ 3–5 ] and excellent mechanical performance, [ 6 ] making it a competitive candidate in preparing functional nanomaterials. Compared with main‐chain liquid crystalline polymers (MCLCPs), side‐chain liquid crystalline polymers (SCLCPs) have significant advantages in terms of chemical structural designability and aggregational structural complexity, which is of great importance in not only fundamental understanding of molecular assembly [ 7–9 ] but also nanotechnology applications. [ 10–12 ] Normally, the self‐assembly structures of SCLCPs can be adjusted from molecular level by changing LC mesogen, [ 13,14 ] flexible spacer, [ 15,16 ] or intermolecular interactions.…”