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Unprecedented Acid‐Promoted Polymerization and Gelation of Acrylamide: A Serendipitous Discovery
Author(s) -
Chan Siew Yin,
Goh Shermin S.,
Dou Qingqing,
Chan Benjamin Qi Yu,
Choo Wee Sim,
Young David James,
Loh Xian Jun
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201800552
Subject(s) - acrylamide , chemistry , self healing hydrogels , chaotropic agent , sonication , aqueous solution , pectin , polymerization , radical polymerization , radical , polymer chemistry , organic chemistry , biochemistry , chromatography , polymer , monomer
Dilute acid polymerizes degassed, aqueous acrylamide with concomitant gelation, without the need for added free radical initiator or cross‐linking agent. This reaction is accelerated by sonication or UV irradiation, but inhibited by adventitious oxygen or the addition of a free radical inhibitor, suggesting an acid‐accelerated free radical process. The resulting hydrogels are thixotropic in nature and partially disrupted by the addition of chaotropic agents, indicating the importance of hydrogen bonding to the 3D network. This discovery was made while trying to prepare pectin‐polyacrylamide hydrogels. We observed that pectin initiated the gelation of acrylamide, but only if the aqueous pectin samples had a pH lower than ca. 5.