Preparation And Properties Of L-aspartic Acid Ionic Liquid/PVA Based Functional Membranes

Conductive substrates are important component of electronic device.They support the operation of electronic device.Traditional conductive substrates are mainly composed of inorganic semiconductor materials（such as silicon base）and Hard polymer base ma-terial.However,their low flexibility,low ductility and rigid brittleness limit their appli-cation in electronic devices.Therefore,soft flexible polymer materials have potential ap-plication value in electronic devices.The excellent transparency and flexibility of poly-vinyl alcohol（PVA）makes it a promising candidate for use in the core components of wearable devices and electronic devices.However,PVA film has the disadvantages of inflammability and insulation,which greatly limits the application of PVA film in elec-tronic devices.Therefore,it is urgent to study the flame retardancy and conductivity of enhanced PVA film.In this paper,L-aspartic acid ionic liquid was used as plasticizer and flame retardant of PVA film,which gave PVA flame retardant property while maintaining its flexibility.Took the flame retardant film as substrate,two-dimensional lamellar Ti₃C₂T_x and one-dimensional rod-shaped multi-walled carbon nanotubes（MWCNTs）as the conductive fillers,and the performance application were studied.The main research contents were as follows:1.Using L-aspartate sulfuric acid ionic liquid（[Asp][HSO₄]）and L-aspartate phos-phoric acid ionic liquid（[Asp][H₂PO₄]）as plasticizers and flame retardants.PVA flame retardant films were prepared by hydrogen/covalent bond interaction between PVA and ionic liquid.Films’structures and properties were analyzed.The results showed that the addition of L-aspartic acid ionic liquid did not reduce the transparency of PVA film.At the same time,due to the plasticization of ionic liquid and its own weak conductivity,the PVA composite film maintained the flexibility and got weak conductivity.When L-aspar-tic acid ionic liquid was added to 20.0 wt%,the limiting oxygen index（LOI）of[Asp][H₂PO₄]/PVA film reached 30.1%,which increased by 58.4%,and the flame retard-ant grade reached V-0.The composite film had good flame retardant property.The per-formance of[Asp][H₂PO₄]/PVA composite membrane was better than that of[Asp][HSO₄]/PVA membrane.[Asp][H₂PO₄]/PVA was selected as the substrate for sub-sequent experiments.2.Using[Asp][H₂PO₄]/PVA as the base material,two-dimensional chip Ti₃C₂T_x was added to the base material as conductive powder（modified by imidazolium hexafluor-phosphate ionic liquid）by integrated blending method and spraying method.Films’prop-erties were tested and analyzed.The results showed that the addition of modified Ti₃C₂T_xgreatly improved the conductivity of[Asp][H₂PO₄]/PVA composite film.When the addi-tion amount was 2.5 wt%,the conductivity of the integrated composite membrane is1.07×10^-3s/m,which was nearly 10 times higher than that of the[Asp][H₂PO₄]/PVA com-posite membrane.The transparency of spraying composite films was less affected,but the surface of the film was rough,and the powder was easy to fall off on the film,the perfor-mance was unstable,which will limit films’application.The surface of the blended com-posite membranes was smooth,and the powder will not fall off easily in the process of use.The sensitivity of the blended composite film in the 0-50%strain range was higher and more stable than that of the spraying type composite film,and the blended composite film maintained good flame retardant.In the follow-up experiments,the blending method was used to prepare composite films.3.Using[Asp][H₂PO₄]/PVA as the base material,one-dimensional rod-modified MWCNTs were used as conductive powder（γ-aminopropyl triethoxysilane as the modi-fier）,and[Asp][H₂PO₄]/PVA/MWCNTs composite membrane was prepared by blend method.The rod-shaped powders were cross-linked to form conductive network.Consid-ering that adding too much powder will greatly weaken the flexibility and transparency of the composite film,the addition amount of powder in this chapter was reduced to 10%of the original compared with the experiment in the previous chapter.When the addition amount of rod-modified MWCNTs was 0.25 wt%,the conductivity reached 80%of the conductivity of[Asp][H₂PO₄]/PVA/Ti₃C₂T_x-2.5,indicating that the conductive network composed of carbon nanotubes was more complete than that composed of Ti₃C₂T_x.Com-pared with[Asp][H₂PO₄]/PVA/Ti₃C₂T_x-2.5 composite films,the percolation threshold was lower,and the modified composite films maintained good flame retardancy.4.Using[Asp][H₂PO₄]/PVA as the base material,the modified two-dimensional lamellated Ti₃C₂T_x and one-dimensional rod-shaped MWCNTs were used as the conduc-tive fillers,and the PVA-[Asp][H₂PO₄]-Ti₃C₂T_x-MCNTs were prepared by an integrated blending method.A more complete conductive network was formed in the composite film.When the total addition of the powder reached 2.5wt%,the MWCNTs were 0.5 wt%,the conductivity reached 9.58×10^-3 s/m.Compared with the single Ti₃C₂T_x packing compo-site film and single MWCNTs packing composite film,increased 795%and 500%respec-tively.The composite film also remained flame retardant.The composite films were tested in human monitoring,and it was found that with the bending of fingers and arms,the resistance of the composite film changed significantly,and the response strength of the composite film was greatly enhanced after soaking in water.The conductive composite film prepared has potential application value in wearable devices and electronic devices.Figure[60]table[17]reference[142]...