Synthesis And Conductivity Properties Of Methyl Methacrylate-Styrene Copolymer/Multiwalled Carbon Nanotube Composites

Carbon nanotubes (CNTs) have excellent mechanical, electrical, thermal and other properties, as an excellent material and doped polymer composite, is considered the great potential of composite materials with broad application prospects. In this thesis, a series of conductive polymer composites of methyl methacrylate-styrene copolymer (P(MMA-St)) and multiwalled carbon nanotubes (MWNTs) were prepared via situ emulsion polymerization and then modified by heat-treatment. The morphology, properties, structure and interaction of the composites were studied. The work is summarized as following:1. Synthesis and characterization of P(MMA-St)/MWNTs compositesP(MMA-St)/MWNTs composites were prepared via situ emulsion polymerization. FESEM show MWNTs were wrapped by P(MMA-St). The results of FTIR, Raman and TGA indicated that some MWNTs could take part in the polymerization of P(MMA-St), which led to the composites containing MWNTs grafted from P(MMA-St). The thermal stability and solubility in ethyl acetate of the composites were significantly improved.2. Study on conducting property of P(MMA-St)/MWNTs compositesThe influence of the MWNTs content and the monomer ratio of P(MMA-St) on the properties of the composites were studied. The results of FESEM, Raman, XPS and TGA indicated that the thermal stability and electrical conductivity of the composites were enhanced with addition of MWNTs. When the content of MWNTs unchanged, the interaction between P(MMA-St) and MWNTs enhanced with increasing the content of PMMA chains segment. P(MMA-St) were encapsulated on the surface of MWCNTs evenly and the thermal stability and electrical conductivity of the composites became higher.3. Study on conducting property of P(MMA-St)/MWNTs composites after temperature modificationThe influence of temperature modification on the conductivity of the composites was studied. The conductivity of the P(MMA-St)/MWNTs composites in the threshold value was increased by2orders of magnitude after temperature modification at200℃for1h. The results of FTIR, XPS and XRD indicated that some ester and acid in the PMMA change into anhydride after temperature modification. The change can prolong the effective conjugation and enhance the interaction between copolymers and MWNTs that the conductivity of the composites improved.