Preparation and Characterization of Waterborne Polyurethane/Hydroxypropyl Chitosan Nanocomposites

New antibacterial polyurethane/chitosan nanocomposites were prepared from waterborne polyurethane (WPU) and water-soluble hydroxylpropyl chitosan (HPCS) in this paper. The structures and properties of WPU/HPCS nanocomposites were analyzed with infrared spectroscopy (IR), transmission electron microscopy (TEM), thermal analysis, tensile test, and microcalorimetric analysis. The results from IA and TEM indicated that WPU latex particles as core were coated with HPCS as shell to form core shell nano-structure by the ionic interaction of anionic carboxyl of WPU and cationic amino of HPCS. The addition of HPCS enhanced the mechanical strength but resulted in the continuous decrease of the enlongation at break for WPU/HPCS nanocomposites. The mechanical strength reached a maximum of 2.5 times of the pure WPU value when the HPCS content was 15 wt%. And also, the incorporation of HPCS into polyurethane matrix caused the improvement of thermal stability and thermal transition for the nanocomposites. With the increased of HPCS content, the swelling ratio of the nanocomposites in organic solvents decreased, whereas it increased in water together with the hydrolytic degree in PBS. The obtained WPU/HPCS nanocomposites had antibacterial activity from the microcalorimetric results. The addition of HPCS could postpone the growth of Escherichia coli, but not completely inhibited the growth of target bacteria.