Poly attached substituted

Extensive studies on photochromic liquid-crystalline polymers have been made by Krongauz et al,2 Liquid-crystalline phases caused marked colour changes of poly(acrylates)98 and poly(siloxanes) substituted with spiropyran side chains upon UV irradiation owing to the aggregation of the photomerocyanines." In contrast, spirooxazines attached to liquid-crystalline polymer backbones displayed no aggregation and hence exhibited normal photochromism similar to that in solution. Fulgimides bound covalently to the side chains of nematic liquid-crystalline polymers also showed normal photochromism. 

Properties have been determined for a series of block copolymers based on poly[3,3-bis(ethoxymethyl)oxetane] and poly [3,3-bis(methoxymethyl)oxetane]- (9-tetrahydrofuran. The block copolymers had properties suggestive of a thermoplastic elastomer (308). POX was a good main chain for a weU-developed smectic Hquid crystalline state when cyano- or fluorine-substituted biphenyls were used as mesogenic groups attached through a four-methylene spacer (309,310). Other side-chain Hquid crystalline polyoxetanes were observed with a spacer-separated azo moiety (311) and with laterally attached mesogenic groups (312). 

Polyphosphazenes sulfonates XIX with the anion covalently attached to the polymer are a new class of cation conductors that have been synthesized by Shriver [625]. They were obtained by reaction of Na0C2H4S03Na with an excess of polydichlorophosphazene in the presence of 15-crown-5, followed by the reaction of the partially substituted product with the sodium salt of poly(ethylene glycol methyl ether). The conductivity at 80 °C of the polymer with x=1.8, m=7.22 is 1.7x10 S cm This low conductivity can be attributed to an extensive ion pair formation between the sodium and sulfonate ions. 

Hydrogen attached to a tertiary hydrogen is most readily substituted secondary hydrogens are only very slowly replaced, while primary hydrogens are quite unreactive. Alkylaromatics react preferentially at the benzylic position. The reaction is accompanied by oxidation to yield carbonyl compounds, acids, and carbon oxides. Other main byproducts are nitrites, alcohols, and large quantities of poly-nitro compounds. 

Reissert chemistry has been employed for polymeric attachment of the isoquinoline heterocycle. Reissert compound (227) reacted with poly(vinylbenzyl chloride) (192) yielding the substitution product (228) in quantitative yield (Scheme 110) (76MI11111). Alkaline hydrolysis of (228) afforded the fully aromatized, polymer-bound isoquinoline derivative (229), again in quantitative yield. In a variation of this reaction (76MI11112), the Reissert... 

Glucose Sensors. Siloxane polymers are known to be extremely flexible. This flexibility will, of course, be sensitive to the amount of side-chain substitution present along the polymer backbone. For instance, in the homopolymer used in these studies (polymer A), the presence of a ferrocenylethyl moiety bound to each silicon subunit should provide an additional degree of steric hindrance, and thus a barrier to rotation about the siloxane backbone, in comparison with the copolymers, which have ferrocene relays attached to only a fraction of the Si atoms. Because these siloxane polymers are insoluble in water, their flexibility is an important factor in their ability to facilitate electron transfer from the reduced enzyme. Relays contained within more rigid redox polymers, such as poly(vinylferrocene), cannot achieve close contact with the enzyme s redox centers and are thus less effective as electron transfer mediators (25,34). The importance of this feature can be seen quite clearly by comparing the mediating ability of the homopolymer A with that of copolymers B-D, as shown in Figures 4 and 5. 

Schliiter et alJ65,66 have recently used rod-shaped polymers1673 such as poly(p-phe-nylene)s and poly([l.l.l]propellane)s as cores for the attachment of convergently generated dendrons. These new branched macromolecules possess a rigid backbone wrapped with structural wedges, which become increasingly more dense toward the outer cylindrical surface. The Pd-catalyzed copolymerization of dibromobiphenyl derivatives with the Frechet-type ethereal dendrons with a substituted aryl diboronic acid afforded the dendritic coated poly(p-phenylene) rod. 

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