photo initiating system to synthesize an absorbent hydrogel

Synthesis of using photo initiating system to prepare an absorbent hydrogel
Abstract
In order to synthesis absorbent hydrogel, Carboxymethyl cellulose (CMC) was prepared by different DS.
A superabsorbent hydrogel of carboxymethylcellulose (CMC) was initiated by UV system using methylenebisacrylamide (MBA) as a crosslinking agent and Photo initiator.
For investigation the reaction of water absorbency of the hydrogels, the synthetic conditions were systematically optimized through studying the influential factors.
The photosensitized vinyl monomers and acrylic monomers onto a range of polymeric substrates has been the subject of particular interest in the recent past (1). Much of this interest originates in the recognition that many of the co-polymeric products possess an interesting range of physical and/or chemical properties.
Among the various methods allowing the generation of radicals, e.g.  irradiation, redox chemical initiation, heating, dye-sensitized reaction and UV light-induced grafting, sensitized reactions are more attractive. UV light-induced grafting allows the use of larger wavelengths of excitation, thus increasing the possibility of potentially valuable commercial exploitation.
However, this kind of reaction requires knowledge of the photo-reactivity of the initiator with respect to the chemical nature of the monomer and of the macroradical. Since polymers absorb light below 300 nm, photosensitiser or photoinitiator that absorb near UV or visible light have been generally added to formulations. The excited molecule may then split and/or react with the subsequent formation of reactive radicals that are capable of attacking the polymeric backbone.
Free radical generation in cellulose, by photosensitized excitation, has shown unequivocally that UV irradiation, both in photosensitized and unsensitised experiments, results in chain scission and radical generation on the glucosidic cycle . By proper choice of the sensitizer, the scission of glucosidic bonds can be reduced and radical generation can be enhanced, thus resulting to a lower degradation of the polymer and an increase in the rate of photochemical reaction.
The reason of this study to produce poly (MBA)-CMC graft copolymer with superabsorbent character
In the current study, a water-soluble photosensitiser, 4-(trimethyl ammonium methyl) benzophenone chloride, symbolized as PI, was used to initiate the graft copolymerization of methylenbisacrylamide onto CMC in an aqueous medium. Factors affecting the graft copolymerization reaction i.e., loading of the photoinitiator and methylenbisacrylamide, irradiation time, polymerization temperature, material: liquor ratio and the DS of the CMC used were studied.