Synthesis and Characterization of Chitosan Based Biocompatible Polyurethanes

Abstract

Polyurethanes can be tailored with outstanding precision for any specific application. The novelty in performance properties of PUs is mainly associated with careful choice of the polyols/polyamines and chain extenders because about 50% volume of PU is comprised of these reactants. Hence, the PUs for desired application can be developed through selecting different polyols and chain extenders. This research project was aimed to synthesis the chitosan based biocompatible PUs for textile applications using isophorone diisocyanate (IPDI), polyethylene glycol (PEG), DPMA and chitosan as chain extender. This study was portioned into three parts. In Part-I, water dispersible PUs were prepared by using mixtures of chitosan (Mol. Wt. 50,000 g/mole) and BDO as chain extender in different mole ratios. In Part-II, PU dispersions were prepared using nanochitosan as chain extender. NCS of 267 nm average particle size was prepared by ionic gelation method. In Part-III, low molecular weight chitosan (CS(LMW)) was used as chain extender. CS(LMW) was prepared by oxidative depolymerization of chitosan with hydrogen peroxide and molecular weight (Mv=12400) was determined by viscometry. The Fourier Transform Infrared (FT-IR) spectroscopy was used for molecular characterization of CS-PU dispersions. The physical properties of CS-PUs including dispersion stability and solid contents were determined and correlated with other findings. The dyed and printed poly-cotton blend fabrics were finished with 10% and 20% solutions of all these CS-PU dispersions by pad-dry-cure method followed by the evaluation of physical, mechanical and antibacterial properties of finished p/c fabrics by standard test procedures. The scanning electron micrographic imaging of finished fabrics was also carried out for morphological study. The pill resistance, ultraviolet protection factor (UPF), Air permeability (AP), crease recovery angle (CRA), tear and tensile strength of the finished blend fabrics were investigated by standard methods and the results revealed that all the chitosan based polyurethane dispersions improved the UPF, CRA, stiffness and tensile strength of the blend fabrics. However, tear strength of the fabrics was decreased. The superior results for CRA, tear and tensile strengths were obtained by applying CS-PUs based on CS(LMW). Finally, antibacterial properties were evaluated by disc diffusion method and no bacterial growth was observed above, below or in close proximity of the fabrics swatches with visible inhibition zones which were improved with the increase in chitosan amount in dispersions.