Molecular weight, effect crystallization

Liquid crystal polymers are also used in electrooptic displays. Side-chain polymers are quite suitable for this purpose, but usually involve much larger elastic and viscous constants, which slow the response of the device (33). The chiral smectic C phase is perhaps best suited for a polymer field effect device. The abiHty to attach dichroic or fluorescent dyes as a proportion of the side groups opens the door to appHcations not easily achieved with low molecular weight Hquid crystals. Polymers with smectic phases have also been used to create laser writable devices (30). The laser can address areas a few micrometers wide, changing a clear state to a strong scattering state or vice versa. Future uses of Hquid crystal polymers may include data storage devices. Polymers with nonlinear optical properties may also become important for device appHcations. 

The initial melt of Ciooo was cooled down to various crystallization temperatures. Typical developments of crystalline domains at 370 K are shown in Fig. 37 here again the lamellae with the marked tapered shape are observed. Quite surprising is that the crystallization of Ciooo is rather fast in spite of the much longer chains. Any growth of lamellae of Ciooo at the temperature of 370 K, where Cioo did not show any appreciable growth, will be an indication of the molecular weight effect. 

Sensitivity to the lethal effects of the high-molecular-weight dye crystal violet for those strains carrying the rfaE mutation ... 

Fig. 7. Effect of Long Alkyl Terminal Groups on the Conformation of Low Molecular Weight Liquid Crystals...

T. Kajiyama, H. Kikuchi, and K. Nakamura, Photoresponsive electrooptical effect of liquid crystalline polymer/low molecular weight liquid crystal composite system, Proc. SPIE 1911, 111-121 (1993). 

Another method for the determination of polymer crystallinity was discussed by Duswalt (159). It is based on the ability of the instrument to cool a molten sample rapidly and reproducibJy to a reselected temperature where isothermal crystallization is allowed to occur. A number of crystallization curves for polyethylene obtained isothermalJy at different, preset crystallization temperatures are shown in Figure 7.57. Differences in polymer crystallizability that may be caused by branching, nucleation, or molecular weight effects can be observed. The sensitivity and speed of the method allow pellet-to-pellet variations in a lot of polymer to be examined. 

To investigate the role of LCP in the composite on the electro-optical properties, PS[4BC/DM]s with the degree of polymerization of 12 and 40 were used as LCP. In order to investigate the role of LCD in the composite on the electro-optical effect, low molecular weight smectic LC, S2 was employed as a sample of composite in which any LCP was not included. S2 is a binary smectic mixture of low molecular weight liquid crystals as shown in Figure 1. The ionic impurities (Pt catalyst) of about 1000 ppm was added to S2 to unify the condition of electric current effect with the (PS[4BC/DM](n=12, 40)/E7) composites which contain about 1000 ppm of Pt catalyst. 

Tsuji, H., Ikada, Y., 1996. Blends of isotactic and atactic poly(lac-tide)s 2. Molecular-weight effects of atactic component on crystallization and morphology of equimolar blends from the melt. Polymer 37, 595—602. 

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