Chemical modification of shaped hydrogels in non-aqueous medium
Center for Innovative Technology
Virginia Polytechnic Institute and State University
Virginia Tech Intellectual Properties, Inc.
Glasser, Wolfgang G.
Frazier, Charles E.
Samaranayake, Gamini S.
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A method is described for the chemical modification of pre-shaped hydrogels in non-aqueous medium. The conditions permit the reaction of highly expanded, porous hydrogel particles, such as spherical beads, using pseudo homogeneous reaction conditions in the absence of water. The method involves a three step procedure in which the porous gels are solvent exchanged int a water-free solvent (step 1) with minimal change in gel dimension and porosity; followed by reaction under non-aqueous condition (step 2); and followed by solvent exchange into water (step 3). Many different types of reactions requiring non-aqueous conditions may be carried out using these conditions. The method has particularly been demonstrated for crosslinking fluorinating beads, and for esterifying beads in a reaction involving multifunctional free carboxylic acids in the presence of dicyclohexylcarbodiimide (DCC).
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