Sulfone polymers properties

The aromatic sulfone polymers are a group of high performance plastics, many of which have relatively closely related stmctures and similar properties (see Polymers containing sulfur, polysulfones). Chemically, all are polyethersulfones, ie, they have both aryl ether (ArOAr) and aryl sulfone (ArS02Ar) linkages in the polymer backbone. The simplest polyethersulfone (5) consists of aromatic rings linked alternately by ether and sulfone groups. 

Modification of the membranes affects the properties. Cross-linking improves mechanical properties and chemical resistivity. Fixed-charge membranes are formed by incorporating polyelectrolytes into polymer solution and cross-linking after the membrane is precipitated (6), or by substituting ionic species onto the polymer chain (eg, sulfonation). Polymer grafting alters surface properties (7). Enzymes are added to react with permeable species (8—11) and reduce fouling (12,13). 

Nafion, a perfluorinated sulfonated polymer, is a typical example of an ion-exchangeable resin with high promise as a catalyst support. Its properties are significantly different from those of common polymers (stability towards strong bases, and strong oxidizing and reducing acids and thermal stability up to at least 120 °C if the counter ion is a proton, and up to 200-235 °C if it is a... 

Other vaginal gels with virucidal properties or capable of interfering with sexually transmitted diseases (in particular with HIV virus) have been reported [25], In particular, gel formulations based on a naphthalene sulfonate polymer named PRO 2000 and dextrin sulfate have been developed as topical microbicides to protect against HIV and other sexually transmitted pathogens. 

Sulfonation is very useful chemical modification of polymer, as it induces high polarity in the polymer changing its chemical as well as physical properties. Sulfonated polymers are also important precursors for ionomer formation [75]. There are reports of sulfonation of ethylene-propylene diene terpolymer (EPDM) [76, 77], polyarylene-ether-sulfone [78], polyaromatic ether ketone [79], polyether ether ketone (PEEK) [80], styrene-ethylene-butylene-styrene block copolymer, (SEBS) [81]. Poly [bis(3-methyl phenoxy) phosphozene] [82], Sulfonated polymers show a distinct peak at 1176 cm"1 due to stretching vibration of 0=S=0 in the -S03H group. Another peak appears at 881 cm 1 due to stretching vibration of S-OH bond. However, the position of different vibrational bands due to sulfonation depends on the nature of the cations as well as types of solvents [75, 76]. 

The ionic aggregates present in an ionomer act as physical crosslinks and drastically change the polymer properties. The blending of two ionomers enhances the compatibility via ion-ion interaction. The compatibilisation of polymer blends by specific ion-dipole and ion-ion interactions has recently received wide attention [93-96]. FT-IR spectroscopy is a powerful technique for investigating such specific interactions [97-99] in an ionic blend made from the acid form of sulfonated polystyrene and poly[(ethyl acrylate - CO (4, vinyl pyridine)]. Datta and co-workers [98] characterised blends of zinc oxide-neutralised maleated EPDM (m-EPDM) and zinc salt of an ethylene-methacrylic acid copolymer (Zn-EMA), wherein Zn-EMA content does not exceed 50% by weight. The blend behaves as an ionic thermoplastic elastomer (ITPE). Blends (Z0, Z5 and Z10) were prepared according to the following formulations [98] ... 

Another way to achieve desirable polymer properties is the modification of preformed polymers. This modification may take place on the reactive sites of the polymer chain through alkylation, hydrolysis, sulfonation, esterification, and other various reactions of polymers. Examples of natural polymers and their modifications are cellulose and its derivatives, chitin and chitosan, and polysaccharides. These are still to this day very important polymers for pharmaceutical applications. 

The beads were transferred to a Buchner funnel, drained free of bulk water by aspiration, and dried in a pyrex dish in a convection oven at 106°C for 8 hr. For measurement of the internal physical properties, the sulfonated polymer must be completely free of water. The atmospherically dried product was washed three times with one bed-volume of methanol for each washing. The methanol-wet beads were dried in a vacuum oven at 50-70°C at full vacuum (760 mm Hg) for 4 hr. The completely dried beads were hygroscopic and had to be handled without exposure to moisture. 

As indicated earlier, another powerful tool for upgrading polymer properties is the postpolymerization reaction of preformed polymers. These reactions may occur on reactive sites dispersed in the polymer main chain. Such reactions include chain extensions, cross-linking, and graft and block copolymer formation. The reactions may also occur on reactive sites attached directly or via other groups/chains to the polymer backbone. Reactions of this type are halogenation, sulfonation, hydrolysis, epoxidation, surface, and other miscellaneous reactions of polymers. In both cases these types of reactions transform existing polymers into those with new and/or improved properties. 

A novel sulfonated copolymer, claimed to be superior to the aforesaid sulfonated polymers, has been introduced for boiler and cooling water treatment [20]. The polymer is said to have a unique composition based on multiple sulfonic acid containing monomers which provide hydrophobic character and high charge density [20]. This composition has been shown to provide a range of exceptional properties. The new polymer demonstrates not only equivalent or better performance for calcium phosphate and zinc stabilization, but also superior thermal stability when compared to other sulfonated polymers. A notable property of the new polymer is its ability to disperse and resolubilize preexisting scale and corrosion product. 

The properties of acid-bearing polymers are determined by (a) the chemical nature of the monomers (b) the microstructure of the polymer (c) their molecular weight and molecular weight distribution and (d) their morphology in the solid state. Sulfonated polymers usually exhibit a much higher proton conductivity than phosphonylated or carboxylated polymers for a given ion content, and generally aromatic polymers exhibit better chemical and thermal stability than aliphatic polymers. Moreover, physicochemical... 

Sulfonated polybenzoimidazole (sPBI) membranes have also been prepared by poly condensation of 2-sulphoterephthalic acid with 1,2,4,5-tetraaminobenzene tetrahydrochloride [193] or by grafting alkyl or aryl sulfonates on to the imidazole ring [194]. ABPBI was sulphonated by immersion in sulfuric acid followed by heat treatment at 450 °C [195]. Other methods of sulphonation have been reviewed by Asensio et al. [196], along with a detailed description of the properties of PBI blends with sulfonated and non-sulfonated polymers, and block PBI copolymers. 

Siegmund G., Klemm D., Cellulose Cellulose sulfonates preparation, properties, subsequent reactions, Polym. News, 27, 2002, 84-90. 

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