The Research Of Functionalized Carbon Nanotube And Its Composite With Polystyrene Nanoparticle

Due to their unique structures, carbon nanotubes (CNTs) own many outstandingproperties, and have been investigated for numerous applications especiallycomposites. However, the application of CNTs is largely impeded by theirinmeltability and insolubility as well as poor compatibility with other matrix materials.In order to improve not only their solubility but also the interactions between matrixand nanotubes for taking full advantage of CNTs in composites, the modification ofCNTs is an effective approach. Besides, the research on preparation of newlyCNT-based composites has recently becoming one of the most important aspectsin science. In this research,4-chloromethylstyrene (CMS) functionalized multi-walledcarbon nanotubes (MWCNTs) were first synthesized by esterification with the aid of aphase transfer catalyst. Based on previous step, a novel polystyrene nanoparticle-MWCNT (PSNP-MWCNT) nanocomposite was prepared by emulsion polymerization.Subsequently, the influencing factors of the above “modified emulsion polymerization”and the effect of three different preparing methods on properties of composites hadbeen studied. The main contributions are as follows:(1) Based on the oxidized MWCNTs, CMS functionalized multi-walled carbonMWCNTs (MWCNT-CMS) were first synthesized by esterification with the aid of aphase transfer catalyst. FT-IR, Raman, UV-vis and fluorescence spectrum resultsreveal that CMS has been attached to MWCNTs via covalent bonding. A core-shellstructure with a thickness of CMS layer in the range of1to1.5nm is observed fromMWCNT-CMS. The weight percentage of grafted CMS is about11wt.%. Theexperiments of solubility and dispersion suggest that MWCNT-CMS can be dispersedstably in various solvents.(2) Based on (1), a novel PSNP-MWCNT nanocomposite was preparedby employing MWCNT-CMS and styrene (St) as reactants via emulsion polymeriza-tion. FT-IR, Raman spectroscopy and so on demonstrate that PSNP has been partlyattached onto the surface of MWNT-CMS through covalent linkages; partly exsit on itsown. After the products was dissolved and repeatedly washed by toluene(MWCNT-PS), results of TEM show that MWCNTs are coated with an amorphouslayer of5~7nm, and the weight percentage of grafted layers for the MWCNT-PS isabout16.7wt.%according to TGA results.(3) The effects of temperature and feed ratio of MWCNT-CMS to St on the preparation of PSNP-MWCNT composites by modified emulsion polymerization wasstudied. By analyzing influences of temperature on conversion as well asthe size and distribution of latex particles, the optimal reaction temperature wasdetermined as70℃. The influences of feed ratio of MWCNT-CMS to St were alsoinvestigated, and when MWCNT-CMS:St=(1-2):100, the PSNP-MWCNT compositeshave better comprehensive performance.(4) The effect of three different preparing methods (modified emulsion polymerize-tion, direct emulsion polymerization and blending method) on properties of PSnanoparticle/MWCNT composites had been compared. According topreliminary study results, the PSNP-MWCNT nanocomposite prepared via modifiedemulsion polymerization has optimum comprehensive properties.