聚合物对多壁碳纳米管的包覆改性研究

探讨了聚合物对碳纳米管的包覆改性.将多壁碳纳米管(MWNTs)通过浓硫酸和浓硝酸的混酸(体积比=3∶1)处理,使其带上羧基.将羧化MWNTs与甲基丙烯酸缩水甘油酯(GMA),苯乙烯双组分接枝聚苯乙烯(PS-g-(GMA-co-St))通过溶液共混方法,使其接在MWNTs上的羧基和GMA所带的环氧基团之间发生酯化反应,实现MWNTs表面接枝上PS-g-(GMA-co-St).扫描电镜观察表明,羧化MWNTs平均管径约为40nm,而接枝上PS-g-(GMA-co-St)的改性MWNTs管径可达约100nm.用四氢呋喃(THF)对表层包覆的PS-g-(GMA-co-St)刻蚀后,其直径降回到约40nm,这和先前观察到的羧化MWNTs的直径基本一致.对刻蚀后的MWNTs样品的FT-IR分析也表明MWNTs表面上存在接枝PS.表面经过PS-g-(GMA-co-St)修饰后,可以形成包覆层,为MWNTs在聚合物基体中分散、制备纳米功能材料提供了途径.

STUDY ON POLYMER SHEATHING ON MULTI-WALL CARBON NANOTUBES

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 acid 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 PS-g-(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 carboxylic or grafted MWNTs,implying that the MWNTs can be sheathed with polymer after modification.After solvent etching through 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.