Abstract:

Thermally-responsive PNIPAm-g-cellulose nanofibers hydrogels were prepared by thermally-responsive poly(N-isopropyl acrylamide)(PNIPAm) grafted electrospun cellulose nanofibrous membranes. The effect of mass ratio of monomer and cellulose, reaction temperature, reaction time and amounts of initiator on grafting rate, swelling rate and morphology were investigated. The results show that the optimum reaction condition are as follows:mass ratio of monomer and cellulose in 15:1, reaction temperature at 40 ℃, reaction time for 3 h and initiator concentration of 10 mmol/L, the grafting rate and swelling rate of PNIPAm-g-Cell at 35% and 31%, respectively. Compared with PNIPAm hydrogels, the lower critical solution temperature(LCST) of PNIPAm-g-Cell hydrogels is obviously increased, indicating that hydrophilic-hydrophobic balance was changed by adding hydrophilic cellulose. Deswelling kinetics of the PNIPAm-g-Cell hydrogels shows that water-retention rate is decreased to 93% and 61% for grafting rate of 25% and 35%, respectively, in initiatory 0.5 min. PNIPAm-g-Cell hydrogels with high grafting rate have greater sensitivity to temperature.

Key words: cellulose, poly(N-isopropyl acrylamide), grafting, thermally-responsive, hydrogels