CN-117511365-B - Polylactic acid/polydopamine/mica nano composite coating and preparation method and application thereof

Abstract

The invention relates to the technical field of composite coatings, and provides a polylactic acid/polydopamine/mica nano composite coating, and a preparation method and application thereof. According to the invention, polydopamine modified mica is used as a nano filler, so that the interfacial compatibility of the mica and polylactic acid can be improved, and stable dispersion of the mica in the polylactic acid can be realized; the film or coating prepared by the coating has excellent mechanical property, thermal stability and ultraviolet shielding property. The polylactic acid/polydopamine/mica nano composite coating is used for preparing the coating on the surface of the substrate, so that the surface glossiness and hardness of the substrate can be improved, and the interface binding force between the substrate and the coating is strong.

Inventors

• NIU XIAOTING
• WEI XINYUE

Assignees

• 东北林业大学

Dates

Publication Date

20260512

Application Date

20231128

Claims (5)

1. 1. The application of the polylactic acid/polydopamine/mica nano composite coating on the surface of the wood is characterized in that the wood and the polylactic acid/polydopamine/mica nano composite coating arranged on the surface of the wood form a coating composite, wherein the polylactic acid/polydopamine/mica nano composite coating comprises polylactic acid and polydopamine modified mica dispersed in the polylactic acid; the polylactic acid/polydopamine/mica nano composite coating comprises polylactic acid, polydopamine modified mica and an organic solvent, wherein the mass of the polydopamine modified mica is 10-25% of that of the polylactic acid, the polydopamine modified mica comprises mica and polydopamine loaded on the mica, and the mica is mica nano sheet; The preparation method of the polylactic acid/polydopamine/mica nano composite coating comprises the following steps: Firstly mixing water, an alkaline buffer solution, mica and dopamine, and centrifuging the obtained mixed solution to obtain polydopamine modified mica, wherein the mass ratio of the mica to the dopamine is 3:4-3:5; The polylactic acid, the organic solvent and the polydopamine modified mica are mixed for the second time to obtain the polylactic acid/polydopamine/mica nano composite coating, wherein the organic solvent is one or two of dichloromethane and chloroform, and the dosage ratio of the polylactic acid to the organic solvent is 1-2 g:20-40 mL; the thickness of the polylactic acid/polydopamine/mica nano composite coating is 80-100 microns.
2. 2. The application of claim 1, wherein the first mixing comprises adding mica into water for ultrasonic dispersion to obtain mica dispersion, adding an alkaline buffer solution into the mica dispersion, adjusting the pH value of a system to 8-10, adding dopamine into the mica dispersion for stirring and mixing, wherein the alkaline buffer solution is Tris-HCl buffer solution, the ultrasonic dispersion power is 280-320W, the ultrasonic dispersion time is 10-20 min, and the stirring and mixing time is 23-25 h.
3. 3. Use according to claim 2, characterized in that the mica is pretreated before being added to water; the pretreatment method comprises ultrasonic cleaning of mica in water, and drying.
4. 4. The use according to claim 1, wherein the second mixing comprises mixing polylactic acid with an organic solvent to obtain a polylactic acid solution, adding the polydopamine modified mica to the polylactic acid solution, and sequentially homogenizing and ultrasonically dispersing.
5. 5. The method according to claim 4, wherein the homogenizing speed is 8000-10000 rpm for 10-15 min, the ultrasonic dispersing power is 280-320W, and the ultrasonic dispersing time is 15-20 min.

Description

Polylactic acid/polydopamine/mica nano composite coating and preparation method and application thereof Technical Field The invention relates to the technical field of composite coatings, in particular to a polylactic acid/polydopamine/mica nano composite coating, and a preparation method and application thereof. Background Polylactic acid is regarded as a promising material because of its excellent safety, biocompatibility and biodegradability. However, the wide use of polylactic acid is still limited by its insufficient properties (such as low heat resistance, low mechanical strength) or complicated manufacturing process, and high cost. In order to further improve the properties of polylactic acid, fillers are generally added to polylactic acid, and inorganic fillers are widely used due to their high aspect ratio and abundant amounts. Compared with graphene oxide, boron nitride and other artificially synthesized nanoscale fillers, the nano mica sheet has more excellent mechanical strength, thermal stability and ultraviolet shielding performance, and has obvious cost advantages. Interfacial adhesion between the polymer and the filler is one of the most important factors affecting the mechanical and thermal properties of the polymer composite. Since polylactic acid and mica have different hydrophobicity, mica is easily agglomerated by adding to polylactic acid. Therefore, there is a need to improve the polarity, roughness and surface activity of mica by an effective and robust strategy to increase the interfacial compatibility between mica and polylactic acid. In recent years, biomimetic modified materials inspired by mussels are attracting attention of researchers due to their environment-friendly properties. Polydopamine (PDA) as a representative of mussel bionic materials has become a research hotspot due to its super-strong adhesiveness, biocompatibility and hydrophilicity to nanomaterials. However, there is no report in the art on improving interfacial compatibility between mica and polylactic acid by modification with polydopamine. Disclosure of Invention In view of the above, the invention provides a polylactic acid/polydopamine/mica nanocomposite coating, and a preparation method and application thereof. According to the invention, the polydopamine is used for modifying the mica, so that the interfacial compatibility between the mica and polylactic acid can be obviously improved, the polydopamine modified mica in the obtained composite coating is uniformly dispersed, and the film or coating prepared by the composite coating is excellent in performance. In order to achieve the above object, the present invention provides the following technical solutions: The polylactic acid/polydopamine/mica nano composite coating comprises polylactic acid, polydopamine modified mica and an organic solvent, wherein the mass of the polydopamine modified mica is 0-25% of that of the polylactic acid and is not 0, and the polydopamine modified mica comprises mica and polydopamine loaded on the mica. Preferably, the mass of the polydopamine modified mica is 5-25% of the mass of the polylactic acid. The invention also provides a preparation method of the polylactic acid/polydopamine/mica nano composite coating, which comprises the following steps: Firstly mixing water, alkaline buffer solution, mica and dopamine, and centrifuging the obtained mixed solution to obtain polydopamine modified mica; And secondly mixing polylactic acid, an organic solvent and the polydopamine modified mica to obtain the polylactic acid/polydopamine/mica nano composite coating. The first mixing method comprises the steps of adding mica into water for ultrasonic dispersion to obtain mica dispersion liquid, adding alkaline buffer solution into the mica dispersion liquid, adjusting the pH value of a system to 8-10, adding dopamine for stirring and mixing, wherein the alkaline buffer solution is Tris-HCl buffer solution, the ultrasonic dispersion power is 280-320W, the ultrasonic dispersion time is 10-20 min, the stirring and mixing time is 23-25 h, and the mass ratio of the mica to the dopamine is 3:4-3:5. Preferably, the mica is pretreated before being added into water, and the pretreatment method comprises the steps of ultrasonically cleaning the mica in water and then drying. Preferably, the second mixing comprises mixing polylactic acid and an organic solvent to obtain a polylactic acid solution, and adding the polydopamine modified mica into the polylactic acid solution, and sequentially homogenizing and ultrasonically dispersing. Preferably, the organic solvent is one or two of dichloromethane and chloroform, the dosage ratio of the polylactic acid to the organic solvent is 1-2 g:20-40 mL, the homogenizing rotating speed is 8000-10000 rpm, the time is 10-15 min, the power of ultrasonic dispersion is 280-320W, and the time is 15-20 min. The invention also provides a polylactic acid/polydopamine/mica nanocomposite, which comprises polylactic ac