External stimuli response on a novel chitosan hydrogel crosslinked with formaldehyde

Abstract

Keeping in mind the significance of hydrogels as an external stimuli sensitive super absorbing material, some transparent covalent hydrogels of chitosan were prepared by crosslinking with varying amounts of formaldehyde solution used as crosslinking agent. The characteristics of hydrogels were investigated by Fourier transform infrared (FT-IR) spectroscopy and swelling experiments. The effect of crosslinking agent on water absorbency has been investigated. The hydrogels exhibited a relatively higher swelling ratio in the range of 2066-3306% and equilibrium water content (EWC) in the range of 95⋅ ⋅38-97⋅ ⋅06% at pH 7 and 35°°C temperature. The influence of external stimuli such as pH, temperature, and ionic strength of the swelling media on equilibrium swelling properties has been observed. Hydrogels showed a typical pH and temperature responsive behaviour such as low pH and high temperature has maximum swelling while high pH and low temperature show minimum swelling. An increase in the ionic strength of swelling media caused a continuous decrease in the swelling of hydrogels at both acidic and basic pH.

Interpenetrated Chitosan-Poly(Acrylic Acid-Co-Acrylamide) Hydrogels. Synthesis, Characterization and Sustained Protein Release Studies

“…Hydrogels are three dimensional hydrophilic polymer networks that swell, but do not dissolve, when brought into contact with water [1]. Hydrogels have been actively studied, particularly those experiencing reversible volume changes in response to external stimulus, such as pH, temperature and ionic concentration.…”

“…Of particular interest are those based on the graft polymerization of monomers such as acryl amide [18], acrylic acid [19], N-isopropylacrylamide [20] and N-vinylpyrrolidone [21] onto chitosan. Chitosan, (1,4)-[2-amino-2-deoxy-β-Dglucan] is a deacetylated derivate of chitin, a natural occurring polymer. It is widely studied in pharmaceutical and biomedical fields because of its biodegradability, biocompatibility, non toxicity and interesting structural properties [22].…”

Sintesis dan Karakterisasi Hidrogel Superabsorben Kitosan Poli(N-Vinilkaprolaktam) (Pnvcl) Dengan Metode Full IPN (Interpenetrating Polymer Network)

“…Rohindra, et al (2004) mensintesis hidrogel kitosan dengan glutaraldehida sebagai agen pengikat silang. Sedangkan sintesis hidrogel kitosan terikat silang formaldehida dilakukan oleh Singh, et al (2006). Modifikasi dengan polimer lain pada pembuatan hidrogel kitosan juga dapat dilakukan, seperti oleh Sadeghi, et al (2011) …”

Synthesis of a Semi-Interpenetrating Polymer Network as a Bioactive Curcumin Film

“…Many polymers including the natural polymers have major drawbacks such as poor mechanical properties and rapid degradation which limits their application in the skin and tissue engineering field. Interest in the use of genipin as a crosslinker is on the increase due to the many toxic effects of other chemical crosslinkers such as glutaraldehyde (25), glyoxal (26), epichlorohydrin (27), and formaldehyde (28). Genipin is extracted from the Gardenia jasminoides fruit and is an iridoid glucoside that has been used by the food industry and Chinese traditional medicine as a blue colorant.…”