Preparation method for polylactic acid grafted chitosan nanowhiskers

A method for preparation of a polylactic acid grafted chitosan (PLA-g-CS) nanowhisker, wherein the method is that:

• after lactide, a catalyst and chitosan are uniformly mixed, polymerization grafting is performed to prepare PLA-g-CS, and then the PLA-g-CS is dispersed into an alkali liquor to obtain the nanowhiskers by a repeated freezing/unfreezing method, with no solvent used in the polymerization grafting process;
• and wherein the method comprises:
• (1) preparation of PLA-g-CS:
• after adding lactide, a catalyst and chitosan are uniformly mixed, performing polymerization grafting to prepare and obtain the PLA-g-CS, wherein a mass ratio of the lactide to the chitosan is (2-10):1;
• and polymerization grafting conditions are:
• nitrogen gas atmosphere, a grafting temperature of 120 to 180° C., and grafting time of 3 to 5 hours;
• and
• (2) preparation of a PLA-g-CS nanowhisker:
• dispersing the PLA-g-CS prepared in step (1) in a mixed solution of NaOH:urea:H2O or LiOH:KOH:urea:H2O to obtain the PLA-g-CS nanowhisker and carrying out freezing/unfreezing, ultrasonic treatment, centrifugation and dialysis, wherein NaOH:urea:H2O=11:4:81, and LiOH:KOH:urea:H2O=(8-15):(5-9):8:(80-85);
• and
• an amount of the PLA-g-CS added is in a range of 0.25% to 0.5%.