Study On Preparation And Performance Of Nano-scale Flexible Electric Heating Films With High Light Transmittance

Free-standing,transparent,and ultrathin films assembled from low-dimensional nanomaterials(LDMs)have great potential for applications in flexible wearable devices,transparent electrothermal films,and many other fields.Although the technology of assembling low-dimensional nanomaterials by vacuum filtration technology is mature.However,efficient and non-destructive self-exfoliation of assembled films is still a great technical challenge,especially the rapid preparation of nano-thick transparent ultrathin films.There is an urgent need to develop a rapid preparation method capable of self-exfoliation to meet the technological development needs of self-supporting transparent ultrathin films.This study proposes a method to fabricate free-standing,transparent,and ultrathin films by creating physical isolation through oxidative bubble formation,exploiting the insufficiency of MXene’s easy oxidation reaction as the key to controllable interfacial reactions and liquid phase separation of the films.The MXene/LDM bilayer membrane was filtered layer by layer by vacuum filtration.The MXene layer in the layer-by-layer filtered MXene/LDM bilayer is dissolved by an oxidant,and the bubble layer is generated in situ to form the physical isolation between the ultrathin film layer and the suction filtration substrate.The stable buoyancy of the bubble layer facilitates the rapid and nondestructive exfoliation of the deposited LDM layer on the liquid surface.The oxidation products of the oxidation reaction of the MXene layer and the physical and chemical morphologies of the ultrathin films before and after preparation were investigated.It was confirmed that the oxidation reaction of the MXene layer does not affect the physicochemical properties of the ultrathin films prepared by this method.The key factors affecting the preparation of ultrathin films,such as MXene sacrificial layer,oxidant and suction filtration substrate,were also studied.The research found that:1)The preparation method is versatile,and a variety of MXene materials,oxidants and suction filtration substrates are suitable for this method.2)The suction filtration base can be reused for many times,and the water flux of the suction filtration base after being used for 5 times still remains above 80%of the initial value.3)The loading of MXene layer is the most important factor affecting the integrity and self-stripping time of ultrathin films.Both too small and too high MXene loadings lead to the integrity of ultrathin films.The optimal loading amount is 500 mg/m~2.The properties of ultrathin films of various low-dimensional nanomaterials have been studied.Using this method,rapid exfoliation of ultrathin films assembled from various low-dimensional nanomaterials including single-walled,double-walled and multi-walled carbon nanotubes,silver nanowires,clay,and carbon nanotubes/Graphene was achieved.The prepared ultrathin films are transparent,self-supporting and thickness-controllable.It only takes 80 s to completely peel off a film with a diameter of 40 mm,a thickness of 15 nm,and a transmittance of more than 90%,through the optimized interfacial reaction.And the preparation process is easy to scale up.The obtained self-supporting film can be easily transferred to any substrate,cut into any shape and reused.The ultrathin,transparent carbon tube films prepared by this method are processed into flexible transparent heaters.The single-walled carbon nanotube electrothermal film with a thickness of 38 nm reaches a steady-state temperature of 235°C within 40 s under an applied voltage of 30 V.It exhibits excellent flexibility,light transmittance and rapid heating and constant temperature performance.It is expected to play an important role in the field of de-icing and anti-icing of aircraft and automobile windows.