Polysiloxane-Based Side Chain Liquid Crystal Polymers: From Synthesis to Structure–Phase Transition Behavior Relationships

Abstract

Abstract:Organosilicon polymer materials play an important role in certain applications due to characteristics of much lower glass transition temperatures (T g ), viscosities, surface energy, as well as good mechanical, thermal stabilities, and insulation performance stemming from the higher bond energy and the larger bond angles of the adjacent silicon-oxygen bond. This critical review highlights developments in the synthesis, structure, and phase transition behaviors of polysiloxane-based side chain liquid crystal polymers (PSCLCPs) of linear and cyclic polysiloxanes containing homopolymers and copolymers. Detailed synthetic strategies are elaborated, and the relationship between molecular structures and liquid crystalline phase transition behaviors is systematically discussed, providing theoretical guidance on the molecular design of the materials.

From Amorphous Silicones to Si-Containing Highly Ordered Polymers: Some Romanian Contributions in the Field

“…Siloxane moieties (short segments, long chains, cycles) are often used in LCs as flexible spacers or as the main backbone, in combination with unnumbered mesogenic groups. The main reasons for using siloxanes instead of purely organic (hydrocarbon) counterparts derive from their bulkiness, high flexibility, chemical versatility and tendency of microphase separation [ 118 , 119 , 120 ]. Several general characteristics of the resulted LC materials are due to these specific behaviors of (poly)siloxanes: lower transition temperatures, larger mesophase range, tendency for formation of smectic mesophases and suppression of the nematic mesophase.…”

Phase Behavior and Phase Diagram of Polystyrene-b-Poly(Perfluorooctylethyl Acrylates)

“…Previously, we reported hierarchical lamellar phases formed in a series of poly(styrene-blockperfluorooctylethyl acrylate) (S-b-F) block polymers bearing perfluorooctylethyl acrylate (FOA) segments on the side-chain position, which also resemble side-chain liquid-crystal-mesogen-bearing compounds [27,32]. We further synthesized samples with a variety of volume fractions, identified the hexagonally and inversed hexagonally packed cylinder phases, and constructed a phase diagram for a thorough understanding of the self-assembly behaviors of these fluorocontaining block polymers.…”

Silicon-Containing Polymeric Materials

“…The versatility of silicon-based materials and silicon’s abundance in the earth’s crust ensure that it will continue to play, in the years to come, a vital role in everyday life. In addition to silicones or polysiloxanes [ 1 , 2 , 3 , 4 ], which have been known and manufactured for many years, silica-reinforced polymers, silsesquioxanes, and POSS-based polymers also offer a multitude of very useful consumer products [ 5 ]. The combination of silicon and oxygen atoms with organic groups has led to the generation of new and modified silicon-containing polymeric materials, thus providing an exciting mixture of properties and offering a wide spectrum of practical applications.…”