CNWs loaded poly(SA) hydrogels: effect of high concentration of CNWs on water uptake and mechanical properties

In this work, poly(sodium acrylate) (poly(SA)) hydrogel films, doped with cellulose nano-whiskers (CNWs), are prepared via free radical polymerization of sodium acrylate (SA) in aqueous medium. The CNWs were added into the polymerization feed mixture, in the concentration range of 4.8-24.3 wt% of monomer and the resulting CNWs/poly(SA) hydrogel films were investigated for their water absorbency in the physiological fluid (PF). The addition of CNWs caused a decrease in the equilibrium water uptake. The kinetic water uptake data of all hydrogel samples were best interpreted by the second order kinetic. The water vapor permeation studies were also carried out. The water vapor transmission rate (WVTR) of all the film samples was quite low. The mechanical properties of films such as tensile strength (TS) and percent elongation (PE) varied with the CNWs content. All the film samples showed fair folding endurance (FE), with more than 600 times folding without suffering from any crack.