Cyclic quaternary ammonium polymers

The formation of covalent branching points is avoided in the cationic polymerization of -substituted aziridines. Chain transfer to polymer occurs, however, leading to formation of branched (or cyclic) quaternary ammonium ions, unreactive in further propagation [165). 

Deliberate production of (vinyl)polystyrene from (toluenesul-foxyethyl)polystyrene or (haloethyl)polystyrenes was best accomplished by quaternization with N,N-dimethylaminoethanol, followed by treatment with base beta-deprotonation is encouraged in the cyclic zwitterionic intermediate. Reaction was faster and cleaner than with other reagents recommended (64, 76, 77) for eliminations, such as alkoxide, diazabicycloundecene or quaternary ammonium hydroxide this new and efficient procedure may find application elsewhere. Hydrometallation or other additions to polymer-bound olefin may prove useful steps in future syntheses by polymer modification. 

A quaternary ammonium hydroxide ion exchange resin 6 was shown to sequester phenols, hydroxypyrazoles, and other weakly acidic heterocycles.25 The sequestered nucleophiles could also be used as polymer-supported reactants. Similarly, the guanidine-functionalized resin 7 was also shown to be a useful capture agent for weakly acidic nucleophiles, including phenols and cyclic iV-acyl sulfonamides.26... 

Following the findings of Butler et al. [5], that diallyl quaternary ammonium halides form water soluble polymers, the structures of polymers produced via a ring-closing mechanism have been the subject of intensive research. A cyclic structure was elucidated and the mechanism was defined as an alternating intra-intermolecular chain propagation, later termed cyclopolymerization [3]. Based on the general scheme presented in Fig. 6 the chemical structure of PDADMAC is determined by... 

Carbon dioxide can effectively be added to the epoxide ring of GVE to produce the corresponding cyclic carbonate, OVE. Quaternary ammonium salt catalysts showed good catalytic activity even at atmospheric pressure of carbon dioxide. Since the blends of poly(OVE-co-AN) and SAN showed good miscibility, catalytic fixation of carbon dioxide to polymer blends via cyclic carbonate could be one of choice for the reduction and utilization of the greenhouse gcis. 

Park et al, reported the synthesis and application of terpolymer bearing cyclic carbonate and cinnamoyl groups. The syntheses of photopolymer with pendant cinnamic ester and cyclic carbonate groups was achieved by the addition reaction of poly(glycidyl methacrylate-co-styrene) with CO2 and then with cinnamoyl chloride. Quaternary ammonium salts showed good catalytic activity for this synthesis. Photochemical reaction experiments revealed that terpolymer with cinnamate and cyclic carbonate groups has good photosensitivity, even in the absence of sensitizer. In order to expand the application of the obtained terpolymer, polymer blends with poly(methyl methacrylate) were also prepared. 

A variety of reusable organic solids like biopolymers such as chitosan (CS), resins and polymers, where quaternary ammonium salts or ILs are supported or grafted, have been investigated with promising yields of cyclic carbonates under mild and moderate reaction conditions [50-64]. 

The cyclic diether, 1,3-dioxolane, is recommended by Ferro Corporation as a more benign solvent substitute for chlorinated organic solvents, such as methylene chloride, 1,2-dichloroethane, and 1,1,1-trichloroethane, and for ketones, such as methyl ethyl ketone (MEK). This ethylene glycol-based ether is a suitable solvent under neutral and basic conditions in several major-use areas. It is a powerful solvent for softening and dissolving polymers made from polar monomers, for example, polycarbonates, acrylates, cellulosics urethanes, phenoUcs, nitriles, urea-formaldehydes, and alkyds, as well as polyesters, vinyl epoxys, and halogen-containing polymers. As a reaction solvent it is added as a component to a special quaternary ammonium or phosphonium salt solution for preparation of a vesicular phenoxy resin. Other beneficial uses for the solvent dioxolane, include ... 

Bases that catalyse the polymerisation or organosilanols and cyclic siloxanes include hydroxides, alcoholates, phenolates and siloxanolates of the alkali metals quaternary ammonium and phosphonium bases, their siloxanolates and fluorides and organolates of the alkali metals quaternary ammonium and phosphonium bases, their siloxanolates and fluorides and organoalkali metal compounds. After polymerisation is complete, the activity of the catalyst must be destroyed. This can be done by neutralisation with chlorosilanes, CO2, etc. The liquid or solid polymers are subsequently cured to form expandable end products. 

The nitrogens of the formed polymer can perform the same reaction, which leads to an unreactive quaternary ammonium ion so that this reaction is a termination. As a consequence, the polymerizations of N-alkylaziridines usually stop at limited conversions. This was first observed for the polymerization of N-methylaziridine by lones et al. The maximum conversions are determined by the concentration of initiator and by the ratio of the rate constant of the propagation over the rate constant of the termination reaction. This ratio, kp/kt, has been taken as a measure of the living character of the polymerization. From kinetic studies and from molecular weight determinations, it was deduced that this termination is predominantly intramolecular, that is, the terminated polymer chains contain a cyclic, nonstrained ammonium ion as an end group (Scheme 9). 

It is clear from the numerous accounts in literature that DMCs can efficiently catalyze the copolymerization of CO2 and epoxides. DMCs can however also be used to develop systems that selectively catalyze the CO2 cycloaddition rather than the copolymerization (Scheme 1.4) as is illustrated by the work of Dharman et al. [20]. By itself, a Zn-Co-DMC is an efficient catalyst for the copolymerization reaction. However, the addition of a quaternary ammonium salt to the reaction mixture switches the selectivity of the catalytic system toward the exclusive formation of the cyclic carbonate. The quaternary ammonium ion plays two important roles in the catalytic system it accelerates the diffusion of CO2 into the reaction mixture and it favors a backbiting mechanism. As such, it hinders the growth of the polymer chain and it enables the selective cyclic carbonate production. Although most zinc-containing catalysts for this reaction are very sensitive toward water, Wei et al. have shown that, for example, the combination of Zn-Co-DMC with CTAB (cetyltrimethylammonium bromide) could even use water-contaminated epoxides as an epoxide feed [21]. 

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