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Side-chain polymers, characteristics

Estimate the characteristic temperatures of the liquid-crystalline side-chain polymer with the following structural unit ... [Pg.180]

The principle of using side chain liquid crystalline polymers as optical storage systems has been estabhshed. This has been demonstrated using a polymer film prepared from a side-chain polymer showing nematic hquid crystalline characteristics with the structure... [Pg.486]

Figure 3.1 represents the characteristic types of mesogenic molecules. Among them are rods, laths, discs, helices which are more popular for physical investigations and technological applications and also main-chain and side-chain polymers. We may add to this list banana- or bent-shape molecules and dendrimers [4] that recently become very popular. [Pg.19]

Extensive studies have been made on poled NLO guest-host systems . The limited solubility of the NLO species in a host matrix and the thermal relaxation of the induced nonlinear optical activity of the poled polymeric films are major disadvantages. Side chain polymers have attracted attention since a large number of NLO molecules may be covalently attached to the polymer chain and the problem of phase segregation of the NLO component is alleviated. In this article, we present the second and third order NLO properties of a new class of guest-host system which possess excellent doping features and photoreactive characteristics. [Pg.237]

As pointed out by Finkelmann in his recent review, the essential features of the phase behaviour of liquid crystalline side-chain polymers are relatively well established. Usually, the DSC trace exhibits a glass transition, characteristic of the polymer backbone, and a first-order transformation from the mesophase to the isotropic phase due to the mesogenic side chains. Complementary studies with a polarizing microscope reveal that the texture observed in the liquid crystalline state can be frozen without change in the glassy state. A given polymer may have several mesomorphous phases and, so far as can be gathered from observations, these are then separated from one another by first-order transition points. [Pg.136]

In this subclass of side-chain polymers, the main chain always consists of a n-conjugated backbone with electron-donating characteristics, the so-called p-type cable, to which several electron-accephng fullerene cages, or an n-type cable, are covalently linked. Owing to its intrinsic electronic properties, numerous double-cable-polymers (D-C) have been employed in electro-optical devices, namely photovoltaic devices (Chapters 7 and 8) [50]. [Pg.9]

Several coumarin-containing methacrylate (8) side-chain polymers have been prepared [106]. The optimum poling temperatures for these side-chain polymers were well above the Tg, a characteristic that is attributed to the absence of flexible spacers between the polymer chain and the bulky cou-marin chromophore. A stable of 13 pm V at 1.064 jxm was obtained at room temperature. A strong dispersion of r.vi, ranging from 2 to 12 pm V in the wavelength range 477 to 1115 nm, was observed in the electrode-poled polymers. [Pg.338]

The regular structure of the alternating copolymer with its absence of side chains enables the polymer to crystallise with close molecular packing and with interchain attraction augmented by the carbonyl groups. As a result these polymers exhibit the following characteristics ... [Pg.279]

Electro-optic The liquid crystal plastics exhibit some of the properties of crystalline solids and still flow easily as liquids (Chapter 6). One group of these materials is based on low polymers with strong field interacting side chains. Using these materials, there has developed a field of electro-optic devices whose characteristics can be changed sharply by the application of an electric field. [Pg.229]

Chemical modifications of PPO by electrophilic substitution of the aromatic backbone provided a variety of new structures with improved gas permeation characteristics. It was found that the substitution degree, main chain rigidity, the bulkiness and flexibility of the side chains and the polarity of the side chains are major parameters controlling the gas permeation properties of the polymer membrane. The broad range of solvents available for the modified structures enhances the possibility of facile preparation of PPO based membrane systems for use in gas separations. [Pg.56]


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See also in sourсe #XX -- [ Pg.12 ]




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