Side-chain liquid crystalline polymers SCLCP

Thermotropic side chain liquid crystalline polymers, SCLCPs... 

Liquid crystallinity can be attained in polymers of various polymer architectures, allowing the chemist to combine properties of macromolecules with the anisotropic properties of LC-phases. Mesogenic imits can be introduced into a polymer chain in different ways, as outhned in Fig. 1. For thermotropic LC systems, the LC-active units can be connected directly to each other in a condensation-type polymer to form the main chain ( main chain liquid crystalline polymers , MCLCPs) or they can be attached to the main chain as side chains ( side chain liquid crystalline polymers , SCLCPs). Calamitic (rod-Uke) as well as discotic mesogens have successfully been incorporated into polymers. Lyotropic LC-systems can also be formed by macromolecides. Amphiphihc block copolymers show this behavior when they have well-defined block structures with narrow molecular weight distributions. 

Unil recently, most side chain liquid crystalline polymers (SCLCPs) were prepared by either hydrosilations of mesogenic olefins with poly(methylsiloxane)s or by free radical polymerizations of acrylates, methacrylates and chloroacrylates [1,2]. Both routes involve chain polymerizations, either directly or prior to a polymer analogous reaction. Chain polymerizations involve the four elementary reactions shown in Scheme 1 [3], In contrast to step polymerizations,... 

Another typical model LCP is PI-14-5CN. It is a nematic side-chain liquid-crystalline polymer (SCLCP), with thechemical structure [54]presented in Figure 11.3. 

LCPs combine the mechanical properties of polymers with the order of LCs. The low molar mass mesogenic units, which form a LC phase, consist of a rigid core. If this core is extended, so-called main chain liquid crystalline polymers (MCLCPs) are obtained. A second method to obtain LCPs is to connect low molecular weight LC (LMWLC) units via flexible spacers. This approach allows the preparation of side chain liquid crystalline polymers (SCLCPs) (Box 1). 

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