C - Chemistry – Metallurgy – 08 – B
Patent
C - Chemistry, Metallurgy
08
B
C08B 3/00 (2006.01) C08B 3/14 (2006.01)
Patent
CA 2185140
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 into 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).
L'invention concerne un procédé de modification chimique d'hydrogels préformés dans un milieu non aqueux, dans des conditions autorisant la réaction pseudo-homogène de particules d'hydrogel extrêmement expansées et poreuses, telles que des perles sphériques, en l'absence d'eau. Ce procédé consiste en trois étapes: on remplace le solvant des gels poreux par un solvant exempt d'eau (étape 1), ce qui modifie peu la dimension et la porosité du gel; on fait intervenir une réaction dans des conditions non aqueuses (étape 2); on remplace le solvant par de l'eau (étape 3). On peut, de ce fait, faire intervenir de nombreuses réactions différentes nécessitant des conditions non aqueuses. Ce procédé s'est avéré particulièrement efficace pour la réticulation de perles de fluoruration, ainsi que pour l'estérification de perles dans une réaction comprenant des acides libres carboxyliques et multifonctionnels en présence de dicyclohexylcarbodiimide (DCC).
Frazier Charles E.
Glasser Wolfgang G.
Samaranayake Gamini
Macrae & Co.
Virginia Tech Intellectual Properties Inc.
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