Side-chain crystalline polymers

Figure 11-1 Sketches of linear polymer in open and coiled form, linear and with side chains, crystalline and...

Bitler [1] prepared sharply melting crystalline polymers consisting of Cg-Cso urea-ethyl-methacrylate, (1), and Caa-acrylate, which reflected high side chain crystallinity and which were used as temperature-dependent coating agents. 

The most intensively developed materials, however, are the azobenzene-containing side chain LC polymers, which show a unique combination of liquid crystallinity and photochromic behavior in a single macromolecule, whereas copolymerization of comonomers with different functionality allows fine tuning of phase behavior, photo-optical properties, and other parameters to the requirements of a particular application. Starting from the first publications of Eich et work in that area has been done by several research... 

Abstract Liquid-crystalline (LC) polymers that exhibit ionic or electronic conduction are described. Anisotropic and efficient transportation of electrons and ions is expected for these materials. The ordered LC nanostructures of LC polymers having ion- or electron-active moieties are important for efficient anisotropic transport. For electron-conductive materials, we focus on side-chain LC polymers. 

We have only dealt with the main chain nematic networks so far. Actually many liquid crystalline networks are formed by crosslinking the backbones of side chain liquid crystalline polymers. The side chain nematic polymers have three nematic phases and their backbones have either prolate or oblate conformations, depending on their phase. It is expected that the rubber elasticity of a side chain nematic polymer network is more complex. For instance, the stress-induced Ni-Nm phase transition is predicted as the network shape transforms from oblate to prolate. Liquid crystalline networks have a bright potential in industry. 

Figure 1.6. Atypical liquid-crystalline side-chain azobenzene polymer.

Liu X H, Bruce DW, Manners I. 1997. Novel calamitic side chain metallomesogenic polymers with ferrocene in the backbone S5mthesis and properties of thermotropic liquid crystalline poly(ferrocenylsilanes). Chem Commun (3) 289 290. 

The measurement of photoinduced birefringence revealed very different anisotropy. Considering the numerous compounds that could readily be complexed with this type of polymer, including chiral adds, phenols, and metals, the approach of using side-chain azopyridine polymers offers the possibility to produce a large number of new photoactive liquid crystalline materials without exhaustive synthetic efforts and with new properties to exploit. And really the approach has been exploited in recent works. The materials similar to that... 

Due to the side chains this polymer is amorphous with a glass transition temperature of 185°C. In contrast, unsubstituted poly(aiylene ether ketone)s are crystalline and high melting > 300°Q. The IR spectrum shows absorption bands at 3,300 cm and 1,710-1,730 cm for the acid group in the side chain and at 1,650 cm for the keto group. 

Poly(CH2-CHCOOROPc)fl C8H17 or C12H25 Side chain phthalocyanine polymers Pc substituted with various groups metal free, Cu and Ni Pc s M up to 47 000 liquid crystalline absorption and fluorescence spectroscopy. [171]... 

In this chapter we will discuss possible realizations of liquid crystalline ordering in conductive polymers. Section II presents basic properties of conducting polymers with a brief description of charge transport mechanisms in those systems. Section III discusses structural types and defects in liquid crystals, and Section IV covers some experimental results of the structural analysis of mesophases in polymers with flexible side chains and polymer/surfactant systems. Sections III and IV are presented to emphasize the properties important to conducting polymers. In Section V experimental data on liquid crystallinity in conductive polymers will be reviewed. Conclusion will be given in Section VI,... 

---