Design And Application Of PVDF-HFP/PAN Bicomponent Nanofiber Composite Fabric Doped With Carbon Nanotubes

At present,multifunctional protective textiles are developed increasingly towards deeper and higher levels with specific properties,such as thermal response,insulation,piezoelectricity,electromagnetic shielding,etc.These textiles are widely used in medical and health care,security and protection,and military applications.It is of great importance for ensuring the safety of people,saving resources and protecting the environment.In this study,multi-walled carbon nanotubes(MWCNT)were doped into polyvinylidene fluoride-hexafluoropropylene(PVDF-HFP)and polyacrylonitrile(PAN)to form different concentrations of spinning solutions.MWCNT-doped PVDF-HFP/PAN two-component nanofiber composite yarns with temperature-control and electromagnetic shielding functions were prepared,and MWCNT-doped PVDF-HFP/PAN two-component nanofiber composite films with piezoelectric and electromagnetic shielding functions were prepared on this basis.1)MWCNT-doped PVDF-HFP/PAN two-component nano yarns were designed and spun by means of conjugate electrostatic spinning and designed as intelligent temperaturecontrolled fabrics.When the humidity of the human body changes,the distance between the fiber changes due to the difference in hydrophobicity of the nanofibers and the distance of the MWCNT changes accordingly,thus enabling temperature control through the electromagnetic coupling effect.Experiments have shown that the designed fabric has a cooling performance of around 5.5°C and a warming effect of around 20°C.The best electromagnetic shielding performance of 29 d B is achieved.The mechanical properties of the single yarn reached 17.78 N.The application of the designed temperature-controlled fabric to a partially temperature-controlled garment also fulfils this function very well.2)MWCNT-doped PVDF-HFP/PAN two-component nanofibrous Janus membranes were designed and spun by means of electrostatic spinning.One layer is a hydrophobic layer,using doped MWCNT to improve the piezoelectric properties of PVDF-HFP,while the other layer uses PAN,which is also piezoelectric and hydrophilic,to induce deformation in response to changes in external humidity.It has been found that high temperatures,high voltage power supplies and near infrared light sources can also cause deformation.The best piezoelectric performance is achieved when multi-walled carbon nanotubes are doped at 5%:5.73 n V and 6.13 n A of current.The best mechanical performance is 1220 k Pa at a MWCNT concentration of 3% and the best electromagnetic shielding performance is 19 d B.The piezoelectric function of this nanofiber composite membrane has been applied to the field of piezoelectric sensing to design piezoelectric sensing gloves and piezoelectric sensing wrist guards to monitor changes in finger and wrist flexion.