surface modification of carbon nanotubes by multi monomer(glycidyl methacrylate and styrene)grafting polystyrene(PS-g-(GMA—co-St))sheathing was carried out．First

Multi—wall carbon nanotubes(MWNTs)was functionalized by a mixture of concentrated sulfuric and nitric acids(3：1

by volume)．As a result

many carboxylic actd groups were created in MWNTs．Carboxylic MWNTs were then mixed with PS-g-(GMA-co—St)／THF solution

and the esterification reaction occurred between carboxylic acid groups of the MWNTs and epoxy groups of PS—g-(GMA-co-St)

leading PSg-(GMA-co-St)grafting onto MWNTs．SEM observation shows that the average diameter of the grafted MWNTs from polymer solution is about 100 nm

larger than the average diameter of about 40 nm for the neat carboxyiic or grafted MWNTs

implying that the MWNTs Can be sheathed with polymer after modification.After solvent etching throush THF

the average diameter of the grafted MWNTs decreased to about 40 nm again

indicating the polymer sheathing can be washed up．Otherwise

after washing-up

FT-IR measurements confirmed that a little polymer still remained on the carboxylic nanotubes．