SDVB copolymers

Sulfonic acid resin from styrene—furfural copolycondensate Sulfonic acid resin from a-pinene—furfural copolycondensate Commercial sulfonic acid resin from phenol—formaldehyde resin Commercial sulfonic acid resin from SDVB copolymer Phosphonic acid resin from PNVC Phosphonic acid resin from NVCF Phosphonic acid resin from PNVCF... 

The cation-exchange resins obtained from SDVB copolymers prepared by conventional pearl polymerization technique mostly have the gel structure. The conventional SDVB copolymer has been modified by using a solvent or a linear.polymer in the monomer mixture during the polymerization to make porous SDVB copolymers. 

Resins from Solvent-Modified SDVB Copolymers. Millar et al. have made a systematic study of the modification of SDVB copolymer networks by carrying out the polymerization in presence of diluents. From such polymers ion-exchange materials have been prepared whose mechanical properties, exchange kinetics, and equilibria differ from those of corresponding materials prepared from SDVB copolymers obtained by conventional method. The diluent may be a solvent, nonsolvent or a poor solvent for the copolymer, and, depending on the nature of the diluent used, the properties of the products differ. 

The characteristic structure of the diluent-modified SDVB copolymers is retained in their sulfonated derivatives. A comparison of the solvent regains of macroporous sulfonic acid resin, conventional sulfonic acid resin, and their parent hydrocarbon matrices is made in Table 1. The sulfonated macroporous product like its parent hydrocarbon copolymer also takes up normally incompatible solvents and the close similarity of their regains in the sulfonated material to the water regain of the hydrocarbon matrices, expressed in compatible units, shows that the macropores have largely survived the sulfonation... 

The ion-exchange resins synthesized from SDVB copolymers obtained by two-stage copolymerization, described as above, have higher porosity, real density, and exchange capacity as compared to those prepared from SDVB copolymers obtained by one-stage polymerization of styrene and DVB The extent of improvement depends on the composition of the first stage. The best properties are obtained when the first stage contains 10% DVB units. 

Furfural-salicylic acid and furfural-P-naphthalenesulfonic acid resins possess thermal stabilityexceeding that of KU-1 (sulfonated phenol-formaldehyde resin) and approaching that of KU-2 (sulfonated SDVB copolymer). The heat resistance of toluenesulfonic acid-furfural resin is quite similar to that of KU-2 resin. The improved thermal stability of furfural-based cation-exchange resins is attributed to the presence of heterocyclic and aromatic rings in these resins. 

The preparation and properties of SDVB copolymers have been described in the preceding section. SDVB copolymers can be converted to anion-exchange resins through chloromethylation with monochlorodimethyl ether using a FriedehCrafts catalyst followed by treatment with different aminesAnderson studied in detail the influence of various Friedel-Crafts catalysts for the diloromethylation of SDVB copolymers. A chlorosulfonic acid — methylal mixture has also been used for the chloromethylation of SDVB copolymers... 

Anion-exchange resins have also been prepared through the nitration of SDVB copolymers with sulfuric acid-nitric acid mixture followed by the reduction of nitro groups with sodium sulfide . Such resins containing —NHj groups have been further modified with ethylenimine or hydroxylamine Aminated polystyrene can be crosslinked with dichloroethane to give an anion-exchange resin... 

The synthesis of anion-exchange resins from acrylonitrile — SDVB copolymer has been reported The copolymer beads are converted to imino ester form by passing dry hydrogen chloride gas into a slurry of the beads in anhydrous methanol at 5 °C. These beads, after washing with anhydrous methanol, are refluxed with a mixture of ethylene diamine and anhydrous methanol. The resin thus synthesized has a capacity of 5 meq/g in Cl" form. Other diamines used for the synthesis of such type of resins are aminoethanolamine, neopentyldiamine, and trimethylenediamine Other monomers which are used for the synthesis of polymer matrices are methyl-acrylonitrile, vinylidene cyanide, cyanoalkyacrylates, and methacrylates, o-, m-, and />-cyanostyrene, 1-cyanobutadiene, 2-cyanobutadiene, methyl, ethyl, propyl,... 

A mixture of SDVB copolymer, thermoplastic polypropylene, and dibutyl phthalate, when extruded at 170-190 °C, gives a composite material which on sulfonation yields an ion-exchange resin suitable for use as a high-temperature ion-exchange catalysts possessing high capacity... 

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