The Research On Functionalization And Liquid Crystalline Polymer Of Multi-walled Carbon Nanotubes

In the work, multi-walled carbon nanotbes (MWNTs) were first functionalized with aryl diazonium salts by solvent-free technique. Subsequently, liquid crystalline polymer HTH-6 was synthesized. MWNTs were further covalently modified by in situ polycondensation of HTH-6 after functionalized with diozanium salts generated by p-aminophenol and MWNT-HTH-6 was obtained. Finally, MWNT-HTH-6/HTH-6 nanocomposite was prepared by solution blend.(1) MWNTs were successfully functionalized with aryl diazonium salts by solvent-free technique. Raman spectroscopy,FTIR,TG-DSC,TEM and dispersibility test were used to characterize the products. In Raman spectra of the resulting materials, characteristic peaks, D- and G-bands, are shifted toward low frequencies for about 10 cm-1. At the same time, the relative intensity ratios between the D- and G-bands increase in comparison to that in the spectrum of purified product. FTIR reveals the presence of the functional groups on their surface. TEM images directly confirm the significant buildup of sidewall organic moieties on the treated materials. The weight loss of various functional moieties determined by TG-DSC is about 18-33%. The dispersibility of functionalized materials in solvents, such as chloroform, tetrahydrofuran and water, is improved obviously.(2) Liquid crystalline polymer HTH-6 was synthesized by polycondensation. Subsequently, the product was characterized using FTIR, HNMR, TGA, DSC and POM. FTIR and HNMR confirm the molecular structure of HTH-6. TGA reveals that HTH-6 is provided with excellent thermal stability and weight loss reaches 5% at 325℃. DSC and POM indicate that HTH-6 is thermotropic liquid crystalline polymer with typical nematic mesophase.(3) MWNTs were functionalized with diozanium salts generated by p-aminophenol and MWNT-ph-OH was obtained. Then, MWNT-ph-OH was further modified by in situ polycondensation of HTH-6 and MWNT-HTH-6 was prepared. MWNT-ph-OH was analyzed by FTIR, Raman spectroscopy, TGA and dispersibility test. The results show that MWNTs were successfully functionalized. FTIR, Raman spectroscopy, SEM, TEM, TGA and solubility test were used to characterize MWNT-HTH-6. The results exhibit that HTH-6 covalently links to carbon nanotubes. According to TGA, HTH-6 holds above 53% in MWNT-HTH-6. More over, MWNT-HTH-6 is dispersible in trifuoroacetic acid for more than a month.(4) MWNT-HTH-6/HTH-6 nanocomposite was prepared by solution blend, followed by characterizing using SEM, TGA and DSC. The results show that MWNTs disperse well in polymer matrix. The temperature of weight loss 5% improves by about 30℃. Melting point does not change, while clearing point improves by 18℃.