Preparation And Multi-Functionalization Of Waterborne Polyurethane/Ag Composite Films

Flexible composite films have attracted the attention of researchers because of their advantages of lightweight,easy processing and portability.In the medical and health monitoring,electronic display,energy storage and other fields have been rapidly popularized.With the continuous development of the industry,the multi-functional application has become a hot research topic.In the preparation process of the product,such as the selection of polymer matrix,the dispersity of filler in the system and other issues are very important for the later application.Therefore,it is still a great challenge to apply flexible composite films to different fields while ensuring the corresponding performance.In this paper,waterborne polyurethane(WPU)was used as substrate and silver(Ag)with different shapes as filler.The composite films with different internal structure were prepared by solution blending and spraying process,and their multifunctional applications were explored.The main research results of this thesis are as follows:(1)Using fluorinated surfactants to reduce the surface tension of water,the Ag microplates/water mixture was obtained.WPU/Ag composite films with a “brick-mud”structure were prepared by spraying.Due to the formation of Ag’s high conductivity and conductive network,the composite films show excellent electromagnetic shielding and electrothermal properties.The electromagnetic shielding efficiency reaches 68.9d B.At a low voltage of 2 V,the surface of the film is heated rapidly to more than 120 ℃.In addition,the composite films show a good tensile strain response to electrical properties.(2)Using D-sorbitol as an additive,WPU/Ag microparticles self-adhesive composite films were prepared by the spraying process.The composite film fits onto the skin without any external help and accurately reflects changes in body movement.When the additive amount was 18.2 wt%,the average adhesion of the sample reached 2.2 N/m.In addition,it not only has good feedback to human fingers,wrist bending and other large strain behaviors but also has stable signal output to the small deformation of the abdomen when breathing,Adam’s apple when coughing and the pulse of the neck.(3)The multilayer composite films were prepared in the sequence of “WPU-Ag microparticles-MXene-WPU” by layer spraying.Through the hot pressing of the silver particle layer,the metal particles produce sintering effect and form a stable and continuous network structure.The results show that the composite multilayer has excellent energy collection and transformation ability.The maximum surface temperatures of the film reached 121.3 ℃ and 66.2 ℃ in the electrothermal and photothermal experiments,respectively.In addition,the composite film is modified into a single-electrode friction nanogenerator by using the difference in charge polarity,which can obtain electrical energy from mechanical motion.