| abstract |
PCT No. PCT/US94/05400 Sec. 371 Date Nov. 8, 1996 Sec. 102(e) Date Nov. 8, 1996 PCT Filed May 13, 1994 PCT Pub. No. WO95/31498 PCT Pub. Date Nov. 23, 1995A microporous, cross-linked, reversibly responsive gel obtainable from a polymeric precursor is disclosed. The microporous gels exhibit a volume change response on the order of seconds, many times faster than nonporous volume change gels of similar dimension. A method of making a microporous, fast response and reversibly responsive gel having a defined pore size and defined strut thickness is also disclosed. The method comprises preparing a polymer solution having a certain initial concentration of polymer precursor, initiating phase separation of the polymer to produce a phase separated state; cross-linking the polymer in its phase separated state or cross-linking the polymer prior in its phase separated state, or both prior to and during its phase separated state, for a certain cross-linking reaction time; and allowing gelation to be completed. Particular uses of the fast response gels are also described. In one embodiment, a method for purifying and concentrating a solute from a solution is described. The method includes the steps of contacting a solution containing the solute with the microporous gel of the invention. Next, the gel is swollen to absorb a portion of the solution and exclude the solute by initiating expansion. This results in a concentrated solution of solute and microporous gel swollen primarily with solution lacking solute. |