# US 11,299,584 B2 · Preparation method for polylactic acid grafted chitosan nanowhiskers

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- Number: US 11,299,584 B2
- Document ID: US11299584B2
- Status: Granted
- Kind: B2
- Application number: 17/481,643
- Filed: 2021-09-22
- Published: 2022-01-06
- Granted: 2022-04-12
- Earliest claimed: 2019-09-30
- Assignees: Jiangnan University
- Applicants: Jiangnan University
- Inventors: Helan Xu; Guiqing Luo; Bomou Ma; Xiuliang Hou
- Web page: https://patentgrep.com/patent/US11299584B2

## CPC

- C08G 63/823: {for the preparation of polylactones or polylactides}
- C08B 37/003: {Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof}
- C08G 63/08: Lactones or lactides
- C08G 63/6852: {derived from hydroxy carboxylic acids}
- C08G 63/88: Post-polymerisation treatment
- C08J 3/075: Macromolecular gels
- C08L 5/08: Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
- C08L 67/04: Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C08L67/06 takes precedence)
- C08L 87/005: {Block or graft polymers not provided for in groups C08L1/00 - C08L85/04}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- C08J 2305/08: Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
- C08J 2487/00: Characterised by the use of unspecified macromolecular compounds, obtained otherwise than by polymerisation reactions only involving unsaturated carbon-to-carbon bonds
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

Disclosed is a preparation method for polylactic acid grafted chitosan nanowhiskers, and belongs to the technical field of materials. The preparation method of the disclosure 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 nanowhiskers by a repeated freezing/unfreezing method, with no solvent used in a polymerization grafting process. The method has advantages that the nanowhiskers can be prepared from the PLA-g-CS without a good solvent, and the whole reaction is efficient, clean, and environmentally friendly.

## Claims

### Claim 1

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%.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the catalyst is stannous octoate, and an amount of the stannous octoate added is 0.1 to 1‰ of the lactide.

### Claim 3 (depends on 1)

The method according to claim 1, wherein freezing conditions in step (2) are a temperature in a range of −80 to −20° C. and time in a range of 0.5 to 3 hours; unfreezing conditions are a temperature in a range of 5 to 10° C. and time in a range of 0.1 to 0.5 hour; and number of freezing/unfreezing cycles is for 2 to 5 times.