Divinyl copolymers

Covalent polymeric networks which are completely disordered. Continuity of structure is provided by an irregular three-dimensional network of covalent links, some of which are crosslinks. The network is uninterrupted and has an infinite molecular weight. Examples are vulcanized rubbers, condensation polymers, vinyl-divinyl copolymers, alkyd and phenolic resins. 

These are the styrene-divinyl copolymer type (HIO) and include Porapak, Polypak, and Chromosorb 102. Five different Porapaks are available P, Q, R, S, and T, which differ in degree of cross-linking of styrene with ethylvinyl benzene. These polymers give sharp, symmetrical peaks and low retention volumes for water, alcohols and glycols, while less polar compounds are retarded (B28, Hll). The beads are stable up to about 250°C. As they are generally used without liquid phase, there is no bleed from the column. Figure 2 shows the excellent results obtained... 

It will be noted that the M291 kit involves a solid (resin) decontamination medium. This is attractive for military use in that the kit provides adsorptive and reactive decontamination, is light in weight and thus easily portable. The resin is a styrene/divinyl copolymer and provides a complex combination of ion-exchange and adsorptive properties. The resin system was found to be less irritating to the skin than the earlier M258A1 water-based system. Preparations based on chloramine and on an N-chloro-oxidant ( Fichlor , sodium... 

Many studies have appeared dealing with the properties of crosslinked polymer systems. These include adhesion of epoxy-acrylates onto tin-plate, adhesion of isocyanate and epoxy-resin coatings, adhesion of butadiene-acrylate rubbers onto metals, glass, and ceramics, adhesion of acrylic, thiol, and polyester resins to aluminium bodies, and the mechanical and physical properties of photo-crosslinkable poly(vinyl cinnamate), vinyl-divinyl copolymers,polythiols, acrylates, epoxies, and thiols,epoxy resins, polyesters on wood, ... 

The two insoluble compounds precipitate and are removed from the water by filtration. Thus by the successive usage of cation and anion-exchange resins sodium chloride could be removed from water. An example of a cation-exchange resin is sulfonated styrene-divinyl-benzene polymer and an anion-exchange resin can be made by chloromethylating styrene-divinyl copolymer and replacing the chlorines with tr i me thy1ami ne. 

Phase separation in networks occurs either in the form of macrosyneresis (deswelling of the gel being crosslinked and formation of continuous liquid and gel phases), or microsyneresis in which the gel and separated liquid phases form a dispersion (e.g. droplets of liquid inside the gel (Fig.l)). In this communication, we will discuss the predictions of the equilibrium theory of macrosyneresis for vinyl-divinyl copolymer-... 

Although they lack commercial importance, many other poly(vinyl acetal)s have been synthesized. These include acetals made from vinyl acetate copolymerized with ethylene (43—46), propjiene (47), isobutjiene (47), acrylonitrile (48), acrolein (49), acrylates (50,47), aHyl ether (51), divinyl ether (52), maleates (53,54), vinyl chloride (55), diaHyl phthalate (56), and starch (graft copolymer) (47). 

Photodegradation may involve use of inherently photo-unstable polymers or the use of photodegradant additives. An example of the former are ethylene-carbon monoxide polymers in which absorption of light by the ketone group leads to chain scission. The polymer becomes brittle and forms a powder. Such materials are marketed by Dow and by Du Pont. Other examples are the copolymers of divinyl ketone with ethylene, propylene or styrene marketed by Eco Atlantic. 

ACPA azobis(4-cyanopentanoic acid) AIBN azobis isobutyronitrile) BPO benzoyl peroxide DVB divinyl benzene, EGA 2-ethylcyano-acrylate HPC hydroxypropyl cellulose MMA methyl methacrylate PAAc polyacrylic acid PEI polyethyleneimine, PEO/PPO polyethylene oxide/polypyropylene oxide copolymer PVME polyvinylmethylether PVP polyvinylpyrrolidone K-30 DMSO dimethylsulfoxide PGA polyglutaraldehyde CMS chloromethylstyrene PMMA-g-OSA polymethylmethacrylate grafted oligostearic acid. 

Polymetric matrix Polydiallyldimethylammonium bromide [9] Polypyrrole [10[ Poly (MA -dimethyb-S -pyrrolidinium bromide [11J Styrene-divinyl benzene copolymers [4] Polyacrylamide [12]... 

A more complicated behaviour was obtained with divinyl ether due to the formation of both cyclic structures and pendent vinyl groups in the chain. The failure of such olefins as styrene and isopropenylbenzene to give copolymers with 2-fural-dehyde, and in fact to homopolymerize in its presence, was blamed on the strength of the complex formed between the initiator and the aldehyde, believed too stable to initiate polymerization. 

In this section wc consider systems where the radical formed by propagation can eyclizc to yield a new propagating radical. Certain 1,4-dicncs undergo cyclocopolymerization with suitable olefins. For example, divinyl ether and MAH are proposed to undergo alternating copolymerization as illustrated in Scheme 4.19.167 These cyclo-copolymerizations can he quantitative only for the case of a strictly alternating copolymer. This can be achieved with certain electron donor-electron acceptor pairs, for example divinyl ether-maleic anhydride. 

Hydroxyl containing polymers may be cross-linked with diisocyanates. Fordyce and Ferry cross-linked styrene-maleic anhydride copolymers through the action of glycols. The copolymerization of divinyl with vinyl monomers may be looked upon as a method of cross-linking chain polymers. The cross-linkages are introduced simultaneously with the growth of the linear polymer chains, rather than afterwards, but this difference is secondary. 

Copolymers prepared from a vinyl monomer and a small proportion of a divinyl monomer are closely related to cross-linked polymers. They will be considered in the final section of the present chapter, where the application of the critical conditions set forth above will be discussed in greater detail. 

Distribution of ortho-, meta-, and para-isomers in the divinyl benzene copolymer... 

Material. Methotrexate-y-hydrazide was prepared by a modified procedure described by Rosowsky (14). Divinyl ether-maleic anhydride copolymer was purchased from Hercules Incorporated (Wilmington, DE) and had an average molecular weight of 11,400. Centriprep-10 concentrators were purchased from Amicon (Danvers, MA). 

Figure 2. Cross-linking of a,o>-divinyl-PDMS by HMS-DMS copolymers.

Lipase CA catalyzed the polymerization of cyclic dicarbonates, cyclobis (hexamethylene carbonate) and cyclobis(diethylene glycol carbonate) to give the corresponding polycarbonates [105]. The enzymatic copolymerization of cyclobis(diethylene glycol carbonate) with DDL produced a random ester-carbonate copolymer. As to enzymatic synthesis of polycarbonates, reported were polycondensations of 1,3-propanediol divinyl dicarbonate with 1,3-propanediol [110], and of diphenyl carbonate with bisphenol-A [111]. 

Ruthenium-catalyzed ATRP was employed in the synthesis of PMMA-fr-PnBuMA block copolymers. Subsequent reaction with the divinyl compound 1 (Scheme 82) resulted in the synthesis of the star-block structures in almost quantitative yield [157]. The divinyl compound 2 was also employed for the Unking of PnBuMA-fr-PMMA through the PMMA blocks. Narrow molecular weight distribution products were obtained in all cases. 

The most widely used type of resin is a copolymer of styrene and divinyl benzene produced in bead form by suspension polymerization in an aqueous medium. 

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