Liquid crystalline polymethacrylates

Scheme 15 Liquid crystalline polymethacrylates 26-28 containing [18]crown-6...

The study by Percec, Tomazos and Willingham (15) looked at the influence of polymer backbone flexibility on the phase transition temperatures of side chain liquid crystalline polymethacrylate, polyacrylate, polymethylsiloxane and polyphosphazene containing a stilbene side chain. Upon cooling from the isotropic state, golymer IV displays a monotropic nematic mesophase between 106 and 64 C. In this study, the polymers with the more rigid backbones displayed enantiotropic liquid crystalline behavior, whereas the polymers with the flexible backbones, including the siloxane and the polyphosphazene, displayed monotropic nematic mesophases. The examples in this study demonstrated how kinetically controlled side chain crystallization influences the thermodynamically controlled mesomorphic phase through the flexibility of the polymer backbone. 

Liquid crystalline polymers containing ferrocene in their side chains have been reported.235-240 Deschenaux used free-radical synthesis to prepare thermotropic liquid crystalline polymethacrylates containing ferrocene (Scheme 2.46).235 Polarized light microscopy showed that monomer 171 and its corresponding polymer 172 exhibited enantiotropic smectic A and C phases. 

There are very few structural studies of thermotropic side-chain polymers under shear flow. Recent work [54] describes the neutron scattering by the liquid crystalline polymethacrylate labelled PMAOC4H9 (Sect. 4.1) in the SmA phase. Typical liquid crystal behavior was observed in which the layers orient... 

Typical examples of the temperature dependence of the relaxation rates of the a- and 6-relaxation (log and log 1 5) are plotted in Figures 8 and 9 for the polymers PM4 and PMg, respectively. The high temperature 6-relaxation process shows a behavior which is also found for liquid-crystalline polymethacrylates carrying phenylbenzoate as mesophase-forming unit (16,23). This means a step-like change of the temperature dependence of log 5 at the transition from the isotropic to the liquid-crystalline state. For the samples PMg and PM5 which have a smectic Wgh temperature phase no further step-like change at the phase transition fi om the smectic high temperature phase to the nematic low temperature phase is observed. This implies that... 

Also, several types of polymeric films were used in this work that are liquid crystalline polymethacrylates with photocrosslinkable mesogenic side groups ... 

Kawatsuki et al., described two different techniques for thermally enhanced photoinduced reorientations of liquid crystalline polymethacrylate films that contain 4-methoxyazobenzene side groups with various alkylene spacer lengths ... 

Polymerization of organoiron monomers has also resulted in the production of liquid crystalline polymers containing ferrocene units in their sidechains. " Scheme 6 illustrates Deschenaux s free-radical synthesis of ferrocene functionalized thermotropic liquid crystalline polymethacrylates Monomer 31 and its corresponding polymer 32 exhibited enantiotropic smectic A and C phases. 

Kreuder W, Webster OW, Ringsdorf H (1986) Liquid crystalline polymethacrylates by group-transfer polymerization. Makromol Chem Rapid Commun 7 5-13.5 Kumar S (2006) Critical review self-organization of disc-like molecules chemical aspects. Chem Soc Rev 35 83-109... 

Rehahn M, Schluter AD, Wegner G (1990) Soluble poly(para-phenylene)s, 3. Variation of the length and the density of the solubilizing side chains. Makromol Chem 191 1991-2003 Reinitzer F (1888) Contributions to the knowledge of cholesterol. Monatsh Chem 9 421-441 Rodekirch G, Riibner J, Zschuppe V, Wolf D, Springer J (1993) New side-group liquid-crystalline polymethacrylates. Makromol Chem 194 1125-1135 Ros MB, Luis Serrano J, Rosario de la Fuente M, Ce SarLF (2005) Banana-shaped liquid crystal a new field to explore. J Mater Chem 15 5093-5098 Rosen BM, Wilson CJ, Wilson DA, Peterca M, Imam MR, Percec V (2009) Dendron-mediated self-assembly, disassembly, and self-organization of complex systems. Chem Rev 109 6275-6540... 

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