Polysulphonates polymer-derived

A range of polysulphones has been prepared with a variety of bis-phenols other than bis-phenol A. As might be expected from the discussion in Chapter 4 and from experience with the range of polycarbonates (Chapter 20), replacement of the isopropylidene link with a methylene, sulphide or oxygen link depresses the Tg whilst —C(CgH5)2— and sulphone links raise it. The bis-phenol derived from norcamphor leads to a polysulphone with a Tg of 250°C (195°C for a Udel-type polymer). 

These materials, the polymeric sulphones, also come into the category of hexavalent sulphur compounds and are derivatives of sulphonic acids. The photochemistry and the radiation chemistry of these substances have been reviewed in a variety of texts. Thus the radiation chemistry was reviewed in considerable detail in 1988147. Other texts have reviewed photodegradation and photooxidation of polymers in general with some reference to the polysulphones149. It appears that polysulphones have low thermal stability and as a result have failed to undergo commercial utilization149. 

Synthetic thermoplastics which soften on heating, e.g., cellulose derivatives, vinyl polymers, saturated polyesters, polyacrylates, polyethers, and polysulphones. 

An obvious need exists for membranes with improved permeability and permselectivity. In addition to several earlier pieces of work contained in ref. Zg and Zh studies involving radiation-modified poly(vinyl alcohol) ordered polycarbonates " and cellulosic ion-exchange membranes have been reported. A variety of reports have appeared of the evaluation of existing polymers, such as polysulphone, in biomedical applications for which they have not previously been used, and of the synthesis of new polymers which may find use in the biomedical area. Examples include polyorganophosphazenes, biodegradable poly(ethyene oxide)-poly(ethylene terephthalate) copolymers, collagen copolymers, block copolymers of l,4-bis(acryloyl) piperazine-AW -dimethylethylene diamine and styrene, and >olymers derived fi om a miscellany of heterocyclic monomers. Information on chemically modified polymers designed for biomedical use is also contained in Chapter 16 of this Volume. 

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