Polymethacrylates, structures

As noted earlier form the work of Freidzon [41], side chain liquid crystal polymers derived from cholesterol can also apparently exhibit TGB phases. However, work on non-steroid systems also reveals that TGB phases can also be formed in typical chiral polymers. For example the polymethacrylate, structure 16, exhibits chiral nematic, TGBA , smectic A , and ferroelectric smectic phases. 

Helix is the most common higher-order structure of synthetic polymers such as peptides, polymethacrylates, polychloral, polyisocyanides, polyisocyanates, and polysilanes. Polyacetylenes bearing appropriate substituents also form a helix. Substituted helical polyacetylenes are promising candidates for enantioselective permeable materials, polarization-sensitive electro-optical materials, asymmetric electrodes, and hence their synthesis is currently under intensive research. This section overviews the synthesis and properties of helical polyacetylenes recently reported. 

The photo-cross-linkability of a polymer depends not only on its chemical structure, but also on its molecular weight and the ordering of the polymer segments. Vinyl polymers, such as PE, PP, polystyrene, polyacrylates, and PVC, predominantly cross-link, whereas vinylidene polymers (polyisobutylene, poly-2-methylstyrene, polymethacrylates, and poly vinylidene chloride) tend to degrade. Likewise, polymers formed from diene monomers and linear condensation products, such as polyesters and polyamides, cross-link easily, whereas cellulose and cellulose derivatives degrade easily. ... 

Webster, O.W. (1990) The control of polymethacrylate molecular structure by group transfer polymerization. Chin. J. Polym. Sci., 8 (1), 1—9. 

Anionic Catalysis Several bulky methacrylates afford highly isotactic, optically active polymers having a single-handed helical structure by asymmetric polymerization. The effective polymerization mechanism is mainly anionic but free-radical catalysis can also lead to helix-sense-selective polymerization. The anionic initiator systems can also be applied for the polymerization of bulky acrylates and acrylamides. The one-handed helical polymethacrylates show an excellent chiral recognition ability when used as a chiral stationary phase for high-performance liquid chromatography (HPLC) [97,98]. 

The structures of polyacrylic acid (PAA) and polymethacrylic acid (PMAA) are shown in Figure 5.2. 

FIGURE 13 Structure of (a) polymethacrylate having binaphthol moiety and (b) simple polymethacrylate CSPs. (From Ref. 37.)... 

Solvent dyes [1] cannot be classified according to a specific chemical type of dyes. Solvent dyes can be found among the azo, disperse, anthraquinone, metal-complex, cationic, and phthalocyanine dyes. The only common characteristic is a chemical structure devoid of sulfonic and carboxylic groups, except for cationic dyes as salts with an organic base as anion. Solvent dyes are basically insoluble in water, but soluble in the different types of solvents. Organic dye salts represent an important type of solvent dyes. Solvent dyes also function as dyes for certain polymers, such as polyacrylonitrile, polystyrene, polymethacrylates, and polyester, in which they are soluble. Polyester dyes are principally disperse dyes (see Section 3.2). 

Several anthraquinone dyes are used in dyeing thermoplastics such as polymethacrylate, (modified) polystyrene, and polycarbonate. The dyes also are used in combination with titanium dioxide or other materials to provide body colors for the thermoplastics. Initially compounds with relatively simple structures were used, many of them drawn from stocks of existing intermediates. Since then new products designed to satisfy the specific requirements have become available. 

Huang G-S, Li Q, Jiang L-X (2002) Structure and damping properties of polydimethylsiloxane and polymethacrylate sequential interpenetrating polymer networks. J Appl Poly Sci 85(3) 545-551... 

It seems, however, that only polyanions are chiefly concerned in the interferon induction. Further polymers having anionic groups have been investigated besides poly(nucleic acid)s and co-(cyclopolymers) 8, for which a partial hydrolysis of the anhydride moiety is supposed. Thus, poly(vinylsulfonate)s or polyacrylates have been found to be active, but, polymethacrylates inactive. It has been shown that in the case of acrylic acid copolymers the molecular weight is also of importance in addition to the structure of the polymer chain and the fraction of carboxy groups. The influence of these various parameters has been discussed in detail by De Somer (45). 

Photoisomerization of a l-oxa-6,6aA4-dithiapentalene leads to the trans structure which reverts rapidly to the original cis compound by a thermal process (equation 3). The rate of the thermal reversal in a polymethacrylate matrix is much smaller than in cyclohexane or ethanol (73JCS(P1)2837,74AG(E)349,77ACS(B)683). This fact rules out the interpretation of the photoisomerization as a valence isomerism as described in equation (4). Effectively,... 

Very important work on the influence of the chemical structure on the temperature of the damping maximum was done by Heijboer (1956-1972), especially regarding the structure of the ester groups in polymethacrylates. 

Several of the important structural features of low molecular weight displacers have been identified on a polymethacrylate based cation exchange support (8 fj, particle size51)- This study made use of the displacer ranking plot described in Section V.C to rank homologous series of molecules which differ from each other in predominantly one structural characteristic. The... 

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