Study On Preparation, Structure And Performance Of Polyaniline/para-phenylenediamine Functionalized MWNTs Conducting Composites

In this dissertation, polyaniline (PANI) / para-phenylenediamine functionalized multi-walled carbon nanotubes conducting composites were prepared by in-situ polymerization. Structure and performance of the composites were studied by using Raman spectra, XPS, TEM,XRD and four probe method et al.Modification does not decrease the integrity of outer graphite sheets in para-phenylenediamine modified MWNTs (p-MWNTs) excessively and results in phenylamine groups with concentration of 3.7% covalently grafted on the surface of p-MWNTs via amide bond. p-MWNTs has the electrical conductivity at room temperature of 71.69 S/cm.Co-axial wrapped hydrochloric acid doped PANI/p-MWNTs conducting composites with core (p-MWNTs)-shell(HCl doped PANI) structure were synthesized by in situ solution polymerization. Phenylamine groups on the surface of p-MWNTs join in situ polymerization, which lead to PANI linked with p-MWNTs via amide bond. Microcrystalline domains are enriched in the inner PANI layers, and with polymerization time extended, more amorphous parts are distributed in the outer layers of PANI coatings. Thermal stability of the composites are highly improved in the range of 300~500℃and electrical conductivities at room temperature for the composites are increased by at least one order of magnitude compared with that of hydrochloric acid doped PANI.DBSA re-doped PANI/p-MWNTs conducting composite with high solubility and stability in N-methyl-2-pyrrolidinone (NMP) was prepared by de-doping HCl doped PANI/p-MWNTs composite and re-doping reaction for the first time. In virtue of the strengthen of chemical bonding between p-MWNTs and polymer chains as well as the solubility of DBSA re-doped PANI, DBSA re-doped PANI/p-MWNTs composite achieves stability for about 1 month and solubility of 35.56mg/mL in NMP. Electrical conductivity at room temperature for the composite is increased by about two orders of magnitude compared with that of DBSA re-doped PANI.Water-soluble and conducting sulfonated polyaniline (SPAN)/p-MWNTs composite was prepared by sulfonation and hydrolysis of HCl doped polyaniline/p-MWNTs composite for the first time. -SO3H groups have been attached to the backbones of SPAN chains with molar ratio of–SO3H groups to nitrogen atoms closed to 1:1. High ratio of S/N in the SPAN/p-MWNTs composite as well as water-soluble SPAN chains covalently attached to p-MWNTs result in the composite soluble in water with solubility of 43.56 mg/mL and stable in water for about 2 month. Electrical conductivity at room temperature for the composite is increased by about two orders of magnitude compared with that of SPAN.DBSA doped PANI/p-MWNTs waterborne latex and conducting composites with solubility and stability in organic solutions were synthesized by in situ emulsion polymerization in the presence of p-MWNTs. Phenylamine groups on the surface of p-MWNTs join in the in-situ polymerization, which lead to PANI linked with p-MWNTs via amide bond and the formation of core(p-MWNTs)-shell(DBSA doped PANI) nano-structures. Order of DBSA doped PANI coatings on the surface of p-MWNTs are increased compared with that of neat DBSA doped PANI. Electrical conductivity at room temperature for the composite is increased by at least one order of magnitude compared with that of neat DBSA doped PANI.