Graft polymerization of vinyl monomers inside macroporous polyacrylamide gel, cryogel, in aqueous and aqueous‐organic media initiated by diperiodatocuprate(III) complexes

Abstract

Graft polymerization initiated by diperiodatocuprate(III) complex (Cu(III)) initiator was found to be an effective and convenient method for graft polymerization of vinyl monomers onto macroporous polyacrylamide gels, the so-called cryogels (pAAm-cryogels). The effect of time, temperature, monomer and initiator concentration during the graft polymerization in aqueous and aqueous-organic media was studied. The graft polymerization of water-soluble monomers as [2-(methacryloyloxy)ethyl]-trimethylammonium chloride, 2-hydroxyethyl methacrylate, N-isopropylacrylamide, and N,N-dimethylacrylamide proceeds with higher grafting yield in aqueous medium, as compared with that in aqueous-organic media. Graft polymerization in aqueous-organic media such as water-DMSO solutions allows grafting of water-insoluble monomers such as glycidyl methacrylate and N-tert-butylacrylamide with high grafting degrees of 100 and 410%, respectively. It was found that the deposition of initiator on the pore surface of cryogels promoted graft polymerization by facilitating the formation of the redox couple Cu(III)-acrylamide group

Cryogels: Morphological, structural and adsorption characterisation

“…When the dense population of polymer brushes is formed, this effect being similar to physical cross-linking of the polymers, it hinders the ionexchange groups inside a more strongly compacted grafted polymer layer, making them inaccessible for large biomolecules. In this case, the adsorption becomes independent of the ionexchange group capacity but depends on the surface area accessible for macromolecules [32,42].…”

“…For instance, macroporous cryogels can have the adsorption capacity for proteins of 3-7 mg/mL [42]. Grafting of such ion-exchange polymers as poly(2-dimethylamino-ethyl methacrylate), polyacrylic acid and poly(2-methacryloyl-oxyethyl-trimethylammonium chloride) to 9 the cryogel surface considerably increases the number of the ion-exchange groups introduced into the cryogel [32]. The ion-exchange capacity of such cryogels does not depend on the matrix surface area anymore as ion-exchange groups are located on the flexible polymer chains attached by one end to the surface of pore walls to form brushes in macropores.…”

“…This is due to the interconnected system of macropores, and the spongy and elastic morphology of the cryogels as a whole [2][3][4][30][31][32][33][34][35][36][37][38][39][40]. These features, in combination with a molecular-imprinting polymer (MIP) technique, provide a new approach for various biotechnological and environmental applications [2,3].…”

“…Polymerisation or crosslinking of a precursor in these liquid inter-crystallite layers results in the formation of relatively thin nano/microporous walls of macropores [2][3][4][30][31][32][33][34][35][36][37][38][39]. The growth of ice crystallites can cause a significant pressure on the formed pore walls.…”

“…Therefore, determination of the amounts of different types of water in cryogels [50,51,54] is of importance to understand the nature of adsorption/desorption and diffusion processes within the pore network in cryogels, as well as to estimate the biocompatibility and structural organisation of whole cryogels [2][3][4][10][11][12][13][14][15][16][17][18][19][20][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]54]. A variety of experimental methods sensitive to the water state can be used for these purposes [50][51][52][53][54][55][56].…”