We controlled the charge through combinations of different polymers: polyacrylamide (PAAm), poly(acrylic acid) (PAA), poly(N-vinylformamide) (PNVF) and polyvinylamine (PVAm). First, the synthesis and characterization of a novel polymer, PNVF, was created from N-vinyl formamide (NVF). NVF is an isomer of acrylamide (AAm), is a liquid monomer at room temperature, which is easier to process than the solid form of AAm; and is less toxic than AAm. PNVF can be easily hydrolyzed to form the cationic gel PVAm. PVAm cannot be formed through direct methods but is beneficial because it has a high charge density and can be readily functionalized. PNVF hydrogels were synthesized by cross-linking aqueous NVF solutions into using a novel cross-linker, 2-(N-vinylformamido)ethylether (NVEE) and the thermally-activated initiator VAZO-44. Although for the same formulation of PNVF as PAAm the PNVF is slightly more hydrophilic, a PNVF formulation can be modified to match the same swelling of a given PAAm gel, thus have the same mechanical strength. Interpenetrating networks have been made of combinations of PNVF, PVAm, PAAm and PAA. Following hydrolysis of the IPN, complexation is controlled at different length scales. With the correctly balanced formulations these gels a collapse due to charge complexation. These materials are being explored as drug delivery platforms. 

Interpenetrating network hydrogels based on poly(N-vinylformamide) and polyacrylamide with controlled charge complexation

245th National Meeting (2013)

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