Resins functional group effect

Even in solution the relative rigidity of the polymer support can play a significant role in the reactivity of attached functional groups. Contrasting studies conducted with chloromethylated derivatives of poly(arylene ether sulfone) (Tg 175°C), phenoxy resin (Tg= 65°C) and polystyrene (Tg= 105°C) allow evaluation of chain rigidity effects. We have shown that the rates of quaternization of chloromethylated poly(arylene ether sulfones) and phenoxy resin deviate from the anticipated second order process at... 

Fig. 2. Preparation of CSG affinity resins of compound without effective inherent functional groups after bioconversion using S9 mixture, (a) Preparation of CSG affinity resins of valdecoxib (5) that has no effective inherent functional groups for immobilization, (b) Capture of C0X2 from sheep placenta lysate (Fig. 2b upper). Due to previously reported structure-activity relationships (8), we believe that conversion of the methyl group to hydroxymethyl was achieved by the S9 treatment. Moreover carbonic anhy-drase type 2 (CA2) was also captured by these resins from THP1, a human leukemic cell line, lysates (Fig. 2b lower). CA2 has been recently reported to be specifically inhibited by valdecoxib at 43 nM (10).

Oxidation studies have been made for cured epoxy resins and the relative stability of the functional groups was established by following the changes in the absorbance ratios of bands associated with the particular functional group 231>. Hence the most unstable groups can be determined easily and their reactions separated from the more stable units. The irreversible 232) and reversible 2331 effects of moisture on epoxy resin systems have also been studied by FT-IR using the difference spectrum method 234). (Fig. 20) shows the interaction spectra obtained after three cycles of water sorption and redrying. The reversible nature of the interactions are clearly demonstrated. 

The use of the anion-exchange resin Duolite A-7 for concentrating organic acids was reported as early as 1965 by Abrams and Breslin (7) and more recently by Leenheer (8). A-7 is a high-surface-area, macro-porous, phenol-formaldehyde, weak-base resin. This resin combines weak-base, secondary-amine functional groups with the relatively hydrophilic phenol-formaldehyde matrix to effectively sorb and elute organic acids. 

The potential effect of chlorine residual on the material used in the concentration scheme (e.g., resin, membranes) must be assessed. Moreover, the development and application of several different concentration schemes require that a strict comparison be based on the recovery of selected model organic substances representative of a wide range of chemical classes, functional group contents, and molecular weights. 

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