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Freezing characteristics of acrylamide-based aqueous solution used for the preparation of supermacroporous cryogels via cryo-copolymerization

Chemical Engineering Science
Publication Date
DOI: 10.1016/j.ces.2006.11.027
  • Supermacroporous Cryogel
  • Monolith
  • Solvent Freezing Crystallization
  • Freezing Curve
  • Freezing Point Temperature
  • Initial Solvent Crystallization Temperature


Abstract Solvent freezing crystallization is a crucial step to the satisfactory formation of homogenous and interconnected supermacropores within cryogels during the preparation of supermacroporous cryogel beds via cryo-copolymerization. In this work, the freezing characteristics of an aqueous solution system containing acrylamide (AAm), N ′ , N ′ -methylene-bis-acrylamide (MBAAm) and allyl glycidyl ether (AGE) for the production of polyacrylamide-based cryogels were investigated experimentally under various cooling conditions. Freezing curves of solution of AAm + AGE + MBAAm under various concentrations were measured to determine the corresponding values of freezing point temperature T mc and the actual initial solvent crystallization temperature T c . The effects of freezing rate and monomer concentration on T c and T mc were addressed. The results showed that the freezing rate had a limited effect on T mc when the freezing rate was very low under the present work. At the same time, T c changed randomly in a certain range with monomer concentration and freezing rate, while T mc decreased with the increase of monomer concentration under freezing condition at a constant freezing rate. Based on these results, the in-column freezing behaviors of 7% (w/w) aqueous solution of AAm + AGE + MBAAm reactive system initiated by ammonium persulfate (APS) and N, N, N ′ , N ′ -tetramethylethylenediamine (TEMED) under different freezing-temperature variation conditions were measured to reveal the actual solvent crystallization processes occurring within the column during the cryo-copolymerization. The properties of these cryogels were also measured and discussed.

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