Preparation And Properties Of Modified Acrylic Acid-based Superabsorbent

Superabsorbent resin is a new type of function polymer which can absorb andretain huge amount of water or aqueous solutions and there are some hydrophilicgroups in their molecular structure，for example，-COOH，-OH and the like. Acrylicacid based superabsorbent which has a high water absorption is one of the mostwidely used superabsorbent. Chitosan，which is a kind of non-toxic，biodegradablenatural polymer，has good compatibility and is an ideal material for preparingantibacterial agent. In this paper， chitosan derivatives were used to modifypolyacrylic acid resin to make it have antibacterial properties. The main contents andconclusions of this paper are as followed:(1) Modified acrylic acid superabsorbent was synthesized by grafting chitosaninto acrylic acid. The structure was characterized by FT-IR and SEM. The effect ofthe following factors，initiator concentration，crosslinking agent concentration，thepolymerization reaction time，neutralization degree of acrylic acid and the weightratio of chitosan and acrylic acid on the swelling capacity was studied.The swellingcapacity was tested at different pH environments. SEM images showed there wereobvious three-dimensional porous structures. The absorption tests showed that asinitiator concentration，crosslinking agent concentration，the polymerization reactiontime，neutralization degree of acrylic acid increased，swelling capacity increasedfirstly，then decreased; as the weight ratio of acrylic acid and chitosan increased，swelling capacity increased; absorbency was sensitive to environmental pH.(2) Chitosan was quaternized by2，3-Epoxypropyltrimethylammonium chloride.Polyacrylic acid superabsorbent grafted quaternary chitosan was obtained by graftcopolymerization. The products were characterized by FTIR，1H NMR and SEM.Swelling capacity of resin was tested at different pH environments. The effect of thefollowing factors，initiator concentration，crosslinking agent concentration，and theweight ratio of acrylic acid to chitosan quaternary ammonium on the swellingcapacity was studied，as well as the antibacterial activity against E.coli and S.aureus.SEM images showed the formation of a three-dimensional structure. Swelling resultsshowed that: Absorbency was sensitive to environmental pH; as initiator concentration，crosslinking concentration increased，swelling capacity improvedfirstly，then decreased; with the ratio of acrylic acid and chitosan quaternaryammonium increased，swelling capacity increased. Antimicrobial experimental resultsshowed that: the hydrogels performed good antibacterial activities against E. coli andS. aureus.(3) Polyacrylic acid superabsorbent grafted with carboxymethyl chitosan wasobtained by graft copolymerization. The products were characterized by FTIR andSEM. The effect of the following factors，crosslinking agent concentration，thepolymerization reaction time and the weight ratio of acrylic acid to carboxymethylchitosan on the ability to absorb water of resin was studied. Water absorbency atdifferent pH environments and water absorption rate was tested. SEM images showedthe interior of resin had formed porous three-dimensional network structure. The testsshowed that as crosslinking agent concentration，the polymerization reaction time，water absorbency of resin increased firstly，then decreased; as the weight ratio ofacrylic acid to carboxymethyl chitosan increased，water absorbency increased;absorbency was sensitive to environmental pH. The absorption rate curves showedthat this three factors had a certain impact on swelling capacity.