Preparation And Performance Of Flexible Conductive Superhydrophobic Films

Flexible conductive sensing nanocomposite materials can produces good perception ability to stress such as stretching,bending and torsion in smart sensors,and it also arouses widespread attraction in wearable sensors,soft robot and human-machine interaction.However,preparation of superhydrophobic nanocomposite materials with excellent flexibility,waterproofing,anti-corrosion,outstanding sensitivity and environmental adaptability remains challenging.Therefore,inspiring by the surface of lotus leaves,the flexible conductive sensing nanocomposite materials with superhydrophobicity is an effective way to realize the self-cleaning,waterproofing and anti-resistance.In this paper,the conductive film are constructed with carbon nanomaterials and thermoplastic elastomers,which has the rough nanoarray on the film and dense conductive network inside the film.The relationships between the geometry of conductive nanomaterials,microstructure of conductive layer and conductive network is researched.In addition,the relationships between strain,deformation of the film and electrical response of strain sensor is also explored.The mechanism of evolution of conductive networks has revealed during the strain response,besides,the superhydrophobic property of flexible films with stretching is also reached.The preparation method of flexible conductive superhydrophobic films with high sensitivity,low resistance and repelling the liquid has been researching.The main research contents are summarized as follows:(1)Adjusting the dispersed state of conductive nanomaterials in the film,the flexible conductive film is endowed with superhydrophobic property for repelling a variety of liquids.Carbon nanotubes and thermoplastic elastomers are used to construct flexible conductive and superhydrophobic TPE/CNTs films by solvent-nonsolvent phase separation at the water/air interface.The stability of response sensitivity of the films in acid,alkali,salt and other liquids is studied.When the amount of CNTs is 1.5mg/mL in CNTs/TPE dispersion,the static contact angle,rolling angle and resistance of the flexible TPE/CNTs film respectively is 162°,2.6° and 14.8 k?,showing excellent superhydrophobicty and conductivity.The superhydrophobic surface on the flexible conductive film has property of anti-wetting and corrosion resistance.Moreover,the film exhibits stable superhydrophobic properties after stretching-restoreing cycles.Results show that the flexible conductive films as a sensor with sensitivity(0.89?1.80),the cycling stability of sensors could reached 1500 cycles,response time(100?150 ms),the response stability of different frequency and response range.(2)In order to realize the synergistic effect of the conductivity and superhydrophobicity on the flexible film.The TPE/CNTs film was prepared at the air/water interface,and decorating the surface with PDMS,the flexible TPE/CNTs/PDMS film with "sandwich" structure.With the 3.0 wt%of PDMS,the static contact angle,rolling angle and resistance of the flexible TPE/CNTs/PDMS film respectively is 165.3°,1.9° and 4.18 k?,which show excellent superhydrophobicity and conductivity.The superhydrophobic surface on the flexible conductive film has property of anti-wetting and corrosion resistance.Moreover,the film exhibits stable superhydrophobic properties after stretching-restoreing cycles.Results show that the sensitivity of the flexible TPE/CNTs/PDMS film is as high as 69.48,the response range is 0%-80%,the response time is 60-80 ms,the cycling stability of response could reached 1000 cycles,and the response stability of different frequencies and response range.The multi-layer conductive network and rough surface of flexible TPE/CNTs/PDMS film realize the synergistic effect of the conductivity and superhydrophobicity.Finally,the flexible conductive superhydrophobic film is used to monitor human pulse,detect pressure response in hot and humid environment and droplet volume.(3)Broadening the advantages of three-dimensional conductive network for high sensitivity,fast response time,and wide range,when it is used as strain sensor.Firstly,the TPU film is impregnated with polyethylenimine(PEI)solution,and then the film is impregnated with carbon black(SCB)dispersion after being dried.The SCB coating on the TPU fibers is repeatedly assembled layer by layer.The CNTs and F-SiO2 dispersion liquid is sprayed on the TPU/SCB film to prepare CNTs/F-SiO2 coating.Finally,the film was impregnated with a mixture of PDMS to form a flexible conductive superamphiphobic multilayer film.When the layer of SCB is 5 layers and the mass ratio of CNTs to F-SiO2 is 3:1,the static contact angle of film is more than 150°,the rolling angle of film is less than 10°,and the resistance is 7.14 k?,which shows that superior superhydrophobicity function and low resistance of the flexible conductive superhydrophobic multilayer film material.The superhydrophobic surface on the flexible conductive film has property of anti-wetting and corrosion resistance.Moreover,the film exhibits stable superhydrophobic properties after stretching-restoreing cycles.Showing that the sensitivity(12.05?60.42),the response time(75?100 ms),the cycling stability of strain sensors could reached 1000 cycles,and the stability for different frequency and response range.The superamphiphobic film as flexible wearable strain sensor can be used to real-time human motion signal detection before and after the infiltration of sweat.In summary,the synergism of superhydrophobicity and conductivity are realized by regulating the distribution of conductive nanomaterials on the surface and inside of flexible conductive materials.Based on the relationship between the geometrical structure of conductive nanomaterials and the conductive paths,the microstructure of the conductive network and the strain response are studied.A new way of flexible conductive superhydrophobic films with high sensitivity and fast response has been obtained for the requirement of repelling the droplets(rain,sweet)in complex environments.We propose a new idea to develop a functional wearable flexible sensor,furthermore lay some experimental methods for the flexible electronic devices for various practical applications in complex environments.