Modification Of Carbon Nano-materials Via Grafting Polymer

Carbon nano-materials have attracted more and more attention since fullerene was discovered in 1985. Among these nano-materials, carbon nanotubes and graphene are the most popular due to their unique structure and excellent physical, chemical, electrical, thermodynamical and mechanical properties. However, carbon nanotubes and graphene have large specific surface area and are easy to aggregate. Carbon nanotubes and graphene are insolubility and can't disperse in most common solvents due to their strong intertube Van Der Waals attraction. These properties have limited their application in most areas. This problem can be solved by modified carbon nano-materials with organic. Carbon nano-materials can decrease nanoparticals' surface energy, change nanoparticals'surface polar, increase their affinity with matrix and decrease particals'aggregate after modified. So it can improve carbon nano-materials'solubility and dispersity in common organic solvent and polymer matrix, and expand their applications.Functionalization of carbon nano-materials with polymers is gaining comperehensive interest because the polymer chains can promote solubility of carbon nano-materials in common solvents. Recently, there are several methods to modify carbon nano-materials with polymers, including physical embedding and in situ radical polymerization. In situ radical polymerization is the most applicable method. It can not only increase carbon nano-materials'solubility, but also improve the stability and conductive of polymers.In this work, polymers were grafted to or grafted from carbon nanotubes and graphene via in situ solution radical polymerization and Friedel-Crafts alkylation reaction. The experiment method, characterizations and results are as follows:1. Polystyrene grafted multiwalled carbon nuanotbes via facile in situ solution radical polymerisationA facile strategy to graft polymers onto the surfaces of multiwalled carbon nano-tubes (MWCNTs) was developed via the free radical addition process in the solution radical polymerisation of styrene in presence of the MWCNTs without any pretreatm-ent so that the length of the original MWCNTs was remained. The effect of the amount of the initiator added and the polymerising temperature on the percentage of grafting (PG%) and conversion of monomer (C%) were calculated. It was found that the maximum PG% of 15.6% was achieved with 0.5% initiator added and the higher polymerising temperature favoured the grafting polymerisation. The polystyrene grafted MWCNTs were characterised with FT-IR, Raman, TGA and TEM techniques.2. Graft polyvinyl chloride to multi-walled carbon nanotubes via Friedel-Craft alkylation reactionPolyvinyl chloride was grafted to multi-walled carbon nanotubes (MWNTs) via Friedel-crafts alkylation reaction for the first time. By using aluminum chloride as catalyst and chloroform as solvent, the effect of amount of catalyst, reaction temperature and time on the grafting percentage was discussed. The grafting percentage was up to 289%. The FT-IR, Raman, and TEM analyses and the comparison of dispersion confirmed that PVC was successfully grafted to MWCNTs by Friedel-crafts alkylation reaction. 3. Polystyrene grafted graphene sheets using facile in situ solution radical polymerizationGraphene sheets were successfully prepared by oxidation-reduction with graphite powder. Then Graphene nanosheets-polystyrene (GNS-PS) composites were successfully prepared by the in-situ free radical solution polymerization. FT-IR, Raman, TGA and GPC analyses were confirmed that PS was successfully grafted from graphenen. It was found that more polystyrene chains with smaller relative molecular weight had been grafted onto the graphene nanosheets via free radical addition with more initiator added in the solution polymerization. GNS-PS well dispersed in polymer matrix, because of the inorganic phase of the graphene and polymer covalently bound.