Design and optimization of polymerization parameters of carboxymethyl chitosan and sodium 2-acrylamido-2-methylpropane sulfonate hydrogels as wound dressing materials

This research focused on the synthesis, characterization and property testing of the hydrogel wound dressing. It was carried out in two main parts, the first part is the synthesis and characterization of carboxymethyl chitosan (CMCTS) and the second part is preparation of hydrogels composed of the sodium 2-acrylamido-2-methylpropane sulfonate (Na-AMPS) and different compositions of CMCTS with various concentrations of poly(ethylene glycol) diacrylate (PEGDA, Mn 575) (crosslinker). CMCTS was synthesized by the direct alkylation method. After purification, the CMCTS was obtained as an off-white powder and was characterized its structure by Fourier transform infrared spectroscopy (FTIR) and proton- and carbon-13 nuclear magnetic resonance spectroscopy (1H-NMR and 13C-NMR). It was found that N,O-carboxymethyl chitosan (N,O-CMCTS) was obtained. The thermal properties of CMCTS was characterized by differential scanning calorimetry (DSC). The degree of substitution (DS) of carboxymethyl groups per chitosan repeat unit and the viscosity-average molecular weight (Mv) of the CMCTS were determined by conductivity titration and dilute-solution viscometry as 1.37 and 3.16 × 104 g/mol, respectively. Hydrogel sheets were then synthesized from Na-AMPS and CMCTS in different compositions and various concentrations of poly(ethylene glycol) diacrylate (PEGDA, Mn 575) (crosslinker). The hydrogel sheets were fabricated by UV-photopolymerization method. The CMCTS was used to blend with Na-AMPS to form semi-interpenetrating polymer network (semi-IPN). A series of hydrogel sheets were characterized in terms of their structures by FTIR, morphologies by scanning electron microscopy (SEM). Additionally, the hydrogels were determined gel content, swelling, water retention, water vapor transmission rate and mechanical properties by tensile testing. The hydrogels sheet was also investigated the skin adhesion and cytotoxicity testing with a view to their potential biomedical use as wound dressings.