Preparation And Properties Of Chitosan Derivatives Superabsorbent Hydrogels

Superabsorbent hydrogels are three-dimensional cross-linked network structure with a large amount of hydrophilic groups.As a result,it can absorb a great lot of water.Superabsorbent hydrogels are mainly made by acrylic base in traditional raw materials.This kind of synthetic superabsorbent hydrogels are poor biodegradability.And with the development of society,the requirement of superabsorbent hydrogels properties becomes higher,like antibacterial activity.The common antibacterial agent to improve antibacterial activity of superabsorbent hydrogels is Ag in previous study.But Ag is not biocompatibility.As a result,other antibacterial agents with biocompatibility have been developed gradually.Chitosan is a kind of natural polymers with good biodegradability and biocompatibility.In our study,N-succinyl chitosan and quaternary ammonium chitosan with good water solubility were chosen as raw materials to prepare superabsorbent hydrogels.The products had excellent water absorbency as well as antibacterial activities.Study contents and the conclusions of this topic are as follows:(1)Superabsorbent hydrogels were prepared successfully from N-succinyl chitosan(NSCS)grafted poly(acrylic acid-co-acrylamide).The potassium persulfate(KPS),N,N'-methylenebisacrylamide(MBA)were used as the initiator and crosslinker respectively.Fourier transform infrared spectroscope(FTIR)and scanning electron microscopy(SEM)were used to confirm the structure of superabsorbent hydrogel.The effects of reaction parameters on swelling behaviors of the superabsorbent hydrogels were investigated.The results indicated that water absorbency increased first,and then decreased gradually with the increase of the contents of monomer(AA+AM),KPS,MAB or acrylamide.The product had excellent water absorbency of 1375 g/g in distilled water and 83 g/g in 0.9 wt% NaCl solution.Simultaneously,the superabsorbent hydrogels were pH sensitive.The antibacterial activities of hydrogels against Escherichia coli were improved effectively because of polyamidoamine(PAMAM)dendrimer absorbed in hydrogels.(2)Superabsorbent hydrogels were successfully synthesized by acrylic acid(AA),acrylamide(AM)and quaternary ammonium chitosan with high substitution degree.And the potassium persulfate(KPS),N,N'-methylenebisacrylamide(MBA)were used as the initiator and crosslinker respectively.Fourier transform infrared spectroscope(FTIR)and scanning electron microscopy(SEM)were used to confirm the structure of superabsorbent hydrogels.The water absorbency and antibacterial activities of the superabsorbent hydrogels against Escherichia coli and Staphylococcus aureus were investigated.With the introduction of quaternary ammonium chitosan,the antibacterial activity was improved.And the contents of crosslinker,initiator and AM had certain influence on water absorbency as well as antibacterial activity against E.coli.AM could enhance the hydrogel strength apparently.In addition,AM(the content was 10%)could increase water absorbency in 0.9 wt% NaCl solution obviously.And the superabsorbent hydrogels were pH sensitive.(3)Chitosan was quaternized modified by 2,3-epoxypropyltrimethylammonium chloride to make 2-hydroxypropyltrimethyl ammonium chloride chitosan(HACC)with different substitution.Superabsorbent hydrogels were made by NSCS and HACC.Epichlorohydrin(ECH)was chosen to be crosslinker.Fourier transform infrared spectroscope(FTIR)and scanning electron microscopy(SEM)were used to confirm the structure of superabsorbent hydrogel.The weight ratio of NSCS and HACC,the content of ECH,the degree of substitution had significant influences on water absorbency and antibacterial activity of superabsorbent hydrogel.The introduction of NSCS could improve the water absorbency,and HACC could improve the antibacterial activity of superabsorbent hydrogel against Escherichia coli.Too less or excess ECH content,concentration of NaOH and degree of substitution would reduce the water absorbency.The higher concentration and degree of substitution of HACC could strengthen the antibacterial activity of superabsorbent hydrogel.Meanwhile,the antibacterial activity of superabsorbent hydrogel was affected by swelling property.The superabsorbent hydrogels were pH sensitive as well.