Cellulosic liquid crystals

Our results [104,117] have shown that the extended chains of ethyl cellulose liquid crystal at high pressures can act as the nucleus of PE ECC and induce the formation of ECC. (The details will be introduced in Section IX.)... 

Figure 13 Schematic diagram of the dependence of <7 on pressure. (F) Denotes folded-chain nucleus, (B) denotes bundle-like nucleus and (B ) denotes addition of ethyl cellulose liquid crystal polymer. (From Refs. 104, 110, 111, and 117.)...

A result different from that of Nakafuku et al. [144-147] was obtained by us from the study of a binary mixture of PE-ethyl cellulose liquid crystal under high pressure. We have reported [104,117] that addition of 1% ethyl cellulose by weight facilitates the formation of ECC of PE and moderates the conditions for the formation of ECC, that is, the pressure limit is lowered from 440 MPa to 150-200 MPa, and the temperature limit lowered from 200-245°C to 170°C. The DSC melting curves at atmospheric pressure for pure PE (Mt, = 1.06 x 10, p = 0.9556 g/cm ) and PE-ethyl cellulose mixture crystallized at various pressures are shown in Figs. 20 and... 

Investigators of cellulosic liquid crystals have two main motivations to study mesophase formation primarily from a scientific viewpoint or a technolomcsd vie oint. The main focus of the latter has been on the potential of preparing high strength/high modulus regenerated cellulose fibers. Another potentim use of cellulosic liquid crystal derivatives is as chiroptical filters (S,lfi). 

Guo, J.-X., and Gray, D. G. (1994). Lyotropic cellulose liquid crystals. In Cellulosic Polymers Blends and Composites, Gilbert, R. D. (Ed.), p. 27. Hanser/Verlag, Munich. 

Woo the temperature dependence of pitch for chiral nematic polymers does not seem to follow any particular pattern. It is believed that as temperature is increased, specific interactions, e.g., hydrogen bonding, whether inter- or intramolecular or polymer-solvent interactions are destroyed. The polymer chains become more flexible and the side groups more easily relaxed, thereby changing the physical properties of the chiral nematic structure. Similarly, an increase in concentration leads to a decrease in pitch for most lyotropic cellulosic liquid crystals with the exception of cellulose tricarbanilate (CTC) in ethyl methyl ketone, 2-penta-none, or tiiethylene glycol monoether and the chlorophenyl urethane derivative in diethylene glycol monoether. ... 

Guo, J.X. Gray, D.G. Lyotropic cellulosics liquid crystals. In Cellulose Polymers, Blends and Composites, Gilbert, R.D., Ed. Hanser New York, 1994 25-46. 

Zhao, C.T. Zhang, G.L. Cai, B.L. Xu, M. Solvent composition dependence of band morphology in sheared lyotropic ethyl cellulose liquid crystals. Macromol. Chem. Phys. 1998, 199 (8), 1485-1488. 

Amphotropic behavior can be found for a large number of different chemical structures. Additional information is given in other chapters of this Handbook. Typical classes of amphotropic materials are for instance classical soaps (see lyotropics), transition metal soaps (see metallomesogens), viologens, quartemary amines and other ionic surfactants (see lyotropics), block copolymers (see polymer liquid crystals), cellulose derivatives (see cellulose liquid crystals) and partially fluorinated paraffines, diols, peptide surfactants, lecithins, lipids, alkylated sugars and inositols, naturally occurring glycosides and silanols, which are discussed in this chapter. 

IX Cellulosic Liquid Crystals Table 5. Cellulose derivatives forming thermotropic LC mesophases. ... 

Extrusion ABS, acetal, acrylic, cellulosics, liquid crystal polymer, nylon, polycarbonate, polyester (thermoplastic), polyethylene, polyphenylene oxide, polypropylene, polystyrene, polysulfone, polyurethane (thermoplastic), PVC, SAN... 

Of particular interest are the ternary systems of ethylcellulose dissolved in a mixed solvent (acrylic acid - water or acrylic acid - glacial acetic acid) and ethylcellulose/ acrylic acid solution blended with a flexible polymer, polyacrylamide. The conclusions of these studies is that, for cellulosic liquid crystals application, the morphology and optical properties of lyotropic liquid crystals can be adjusted by solvent mixing and blending with other polymers. 

D. G. Gray, Chemical characteristics of cellulosic liquid crystals. Faraday Discuss. Chem. Soc. 79, 257-264 (1985). 

M. Ito, Y. Teramoto, and Y. Nishio, Electrooptical behavior of aqueous (hydroxypropyl)cellulose liquid crystals containing imidazolium salts. Biomacromolecules 13, 565-569 (2012). 

---