The Preparation Of Poly (Vinyl Alcohol) Multi-Walled Carbon Nanotubes Nanofiber Mat And Its Self-assembly

Along with the fast development electrospinning, it has been successfully used in the preparation of various nano fiber materials. Duing to their excellent properties, carbon nanotubes are applied to producing some useful nanomaterials by electrospinning gradually. Meanwhile, the application of carbon nanotube as the basic material in the transparent conductive film also catches wide attentiont. To a certain extent, applying the effective electrospinning technology to the field of carbon nanotube transparent conductive film can help to offer a new way.In this dissertation, Poly(vinyl acohol) (PVA)/Multi-walled carbon nanotubes (MWNTs) composite nanofiber mat were prepared by electrospinning, and the porous nanofiber mat became to a compact film by self-assembling in water, systematically, the mechanism of this self-assembly phenomenon were discussed, and the main contents include:1. MWNTs were functionalized with hydroxyl (-OH) and carboxyl (-COOH) groups by acidification method, a clear contrast were made between the distribution effect of MWNTs-OH and MWNTs-COOH and their interactions with cotton and PVA. The special solution airing method helped to prove that MWNTs-COOH had better dispersion as it had stronger combination with water molecules than MWNTs-OH, but MWNTs-OH can more easily wriggle itself free, so it had stronger bond with cotton and PVA. So MWNTs-OH were chosed as basic material in the further experiments.2. PVA/MWNTs-OH nanofibers were prepared by electrospinning, and the relationship between concentration of PVA,the adding amount of MWNTs-OH and the fiber morphology were discussed by SEM,FT-IR and DSC methods. It could get the best spinning effect when the concentration of PVA was 10% and the adding amount of MWNTs-OH was 2.5 mg/ml in the spinning solution. And as to the decomposition temperature of PVA/MWNTs-OH nanofiber, a critical value of MWNTs-OH content were found. 3. PVA/MWNTs-OH nanofiber mat started to self-assemble when it was put in water, it shrinked gruadually and finally hanged to another transparent and compact film. Characteristics of PVA/MWNTs-OH nanofiber mat self-assembly were described in details by XRD and SEM, such as mass conservation multilayers,controllability of the light transmittance and contractibility rate as well as moldability. What's more, the essential conditions of happening self-assembly were discussed by some other water-soluble film, it's proved that the special structure of nanofiber mat,characteristics and cotent of MWNTs-OH, and the water solubility of PVA played a great role in the self-assembly process.4. According to the experiment result and some raleted researches, we made a reasonable deduction of self-assembly process:①the PVA/MWNTs-OH nanofiber mat was wetted by water;②the absorption of water leaded to PVA swelling, and the activity ability of molecular chains improved;③PVA started to nuclear crystallize on the surface of MWNTs-OH;④duing to the van der Waals force, MWNTs-OH wrapped with PVA agglomerated quickly and PVA molecule chains rearrange along the MWNTs-OH surface;⑤the reunion of carbon nanotubes and PVA mixture gradually tended to the lowest energy state, and the self-assemble completed when they were at the most stable condition.