Cross-linked with divinyl sulfone

The first cross-linked hyaluronan gel developed and clinically tested for dermal augmentation was produced by cross-linking with divinyl sulfone (DVS hylan B)... 

Since Merle s data indicate that deviation from ideality of the charged species is negligible in the gel, contrary to expectations derived from the preceeding analysis, we reexamined the potentiometric properties of the flexible carboxymethyldextran gel system (Sephadex CM-50) studied by Merle. We also carried out a parallel investigation of the much more rigid PM A resin (IRC-50) cross-linked with approximately 5 wt % divinyl benzene. The titrations of these polymers with standard b,ase were made in the presence of sodium polystyrene sulfonate. The pH and pNa of the solution phase and the volume (Vp) of the gel (resin) phase were measured at selected a values covering the complete neutralization range. 

Fig. 11.10 Water uptake isotherms of various ionomers and sulfuric acid at 80 C. Dowex 50 is an ion-exchange resin made of 4% cross-linked polystyrene divinyl benzene BPSH 40 is a 2-mil 40% randomly sulfonated biphenol sulfone 700 EW PFSA is a 1-mil membrane with a structure similar to Nafion Nafion 112 is a 2-mil extruded membrane and, PAEK triblock is a 1-mil triblock polyaryl ether ketone with a sulfonated middle block (Reproduced from C.K. Mittelsteadt and H. Liu. [30] by permission from John Wiley Sons)...

Armes and co-workers [242, 243] have also extended their pioneering work on aminoacrylate-based block copolymers to micellar studies of A-B-C copolymers such as PEO-PDMAEMA-PDEAEMA and PEO-PDMAEMA-PBAEMA in which the central PDMAEMA block was cross-linked by a difimctional alkyl iodide. For PEO-PHEMA-PDEAEMA, in view of biomedical applications, this cross-linking could preferably be achieved with divinyl sulfone, that reacts selectively with the hydroxylated PHEMA block. 

Figure 10 Separation of monochloroacetate, dichloroacetate, and trichloroacetate on a sulfonated poly(styrene-divinyl benzene) column with suppressed conductivity detection. Column 2% cross-linked sulfonated poly(styrene-divinyl benzene) capacity 0.02 meq/g. Flow rate 64 ml/hr. Eluant 15 mM sodium phenate. Suppressor 0.28 x 25 cm Dowex 50W X8 column (200-400 mesh). Detector Chromatronix conductivity cell connected to a Dow conductivity meter. (Reprinted with permission from Small, H., Stevens, T. S., and Bauman, W. C., Anal. Chem., 47,1801,1975. 1975 Analytical Chemistry.)...

There is experimental evidence to support the estimate that t/H = t/Na in this system. In the research of Travers and one of the present authors (2), a study of the complexation of divalent metal ions by poly-methacrylic acid (PMA) showed that deviation from ideality with a of the divalent ions exposed to the same potential as the H+ ion was described exactly by the deviation term deduced from the potentiometric properties of the PMA. Additional evidence for this estimate is available in the ion-exchange literature (3,4,5). At a relatively low cross-linking percentage (2 wt % divinyl benzene) j/h is about equal to t/Na> as evidenced by the ion-exchange distribution of Na+ and H+ between a polystyrene sulfonate-based resin and a simple dilute electrolyte mixture of Na+ and H+ (Na H+, X"). The selectivity coefficient measured over the complete composition range of the resin deviates very little from unity to demonstrate this as an experimental fact (KHNa = 1.02 zt 0.02... 

To overcome such limitations, Imura et al. covered the surface of a silica gel with sulfonated cross-linked polystyrene [5]. After adsorption of styrene, divinyl-benzene, and r-butyl peroxide and subsequent free-radical polymerization, the acid groups are introduced via classical sulfonation. Control of the thickness of the crosslinked polymer layer on the surface is essential to prevent pore clogging. This sulfonated polystyrene-Si02 hybrid material preserves a large specific surface area, with a typical ion-exchange capacity of 1.8 meq g. Alternatively, a sulfonated layer can be deposited on silica by copolymerization of silica-supported methacrylate and potassium p-styrene sulfonate [6]. 

Hydrogels were synthesized by cross-linking HA with DVS and poly (ethylene glycol)-functionalized divinyl sulfone (VS-PEG-VS). These gels were loaded with vitamin E succinate (VES) and bovine serum albumin (BSA), as models of antiinflammatory proteins and drugs, and their release kinetics were measured in vitro. The rate of release from HA-VS-PEG-VS-HA hydrogels was faster than that from HA-DVS-HA hydrogels, presumably because of the lower cross-linked density in the former (75). 

Difunctional reagents containing two active vinyl groups are capable of reacting with reduced keratin hbers and forming cross-links. Divinyl sulfone has been used for this purpose [91],... 

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