Study On The Effect Of Pore Structure And Functional Group On The Conductivity Of Coal/PAN Composite

Coal/PAN complexes were synthesized by aniline monomer in situ polymerization in coal template initiated by APS, taking advantages of the acidic functional group, pore structure and specific aromatic ring of coal structure. Pore structure and functional groups were the key factors that affect the conductivity of Coal/PAN complexes. Based on the investigation of coal structure and properties, the effect of pore structure and functional groups on the conductivity of Coal/PAN complexes was mainly investigated from three aspects in this dissertation. HNO3, H2O2 and aniline extraction were chosen to change the pore structure in coal. The analysis results of conductivity, FTIR, and pore structure indicated that the conductivity of Coal/PAN was improved by oxidation and extraction, which developed the pore structure in coal, and then facilitated the process of aniline entering the swelled coal pore.Two methods were applied to investigate the effect of the change of functional groups change in coal on the conductivity of Coal/PAN. First, from the analysis of the total acidic groups in row coal and oxidized coal, FTIR, and conductivity change, the hydrolytic decomposition of weak ether bands and the transformation of carboxylate to carboxylic acid during coal oxidation increased the total acidic groups (—OH and —COOH) in coal. The increase of —OH and —COOH groups was benefit to improve the action between coal and aniline, in turn, increased the conductivity of the complex with a maximum of 4.72×10-1 S/cm. Second, two methods of introducing sulfonic groups into coal were investigated. From conductivity comparison, both methods were proved to be benefit to improve the conductivity of Coal/PAN. Proton acids doping caused the inter-molecular and inner-molecular delocalization in PAN and improved the conductivity. On the other hand, the sulfonic groups were relatively large, the inter-molecular action of PAN was decreased with sulfonic groups doping in PAN. The extension state of PAN molecules conformational also enhanced the charge delocalization, and then increased the conductivity.For further investigation of the effect of pore structure and functional groups on the conductivity of Coal/PAN, an aniline extracted product was used as the template to simulate the effect of through pore in free-ash coal on the conductivity of the complex, producing a complex with a maximum conductivity of 6.46×10-4 S/cm. Though the extracted product was a kind of natural porous material with superior performance, in the surface, there were less －OH, －COOH, =C=O, low density electric charge and less active site than that in un-extracted coal, which resulted in a relatively weak "hydration" in the surface. Thus it was difficult to distribute the extracted products in water. And then the polymer doping process was unable to be well done. Synthesizing the above analysis , the cooperation effect of pore structure and functional groups that enhanced the conductivity of Coal/PAN complex.