Kang Youngjong, Taton T Andrew
Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
J Am Chem Soc. 2003 May 14;125(19):5650-1. doi: 10.1021/ja034082d.
We report a general approach toward dispersing single-walled carbon nanotubes (SWNTs) in solvents and polymer materials, by encapsulating SWNTs within cross-linked micelles. Micelles made from polystyrene-block-poly(acrylic acid) (PS-b-PAA), an amphiphilic block copolymer, are first assembled around SWNTs by gradually adding H2O to a suspension of nanotubes in dimethylformamide. The hydrophilic, outer shells of these micelles are then chemically cross-linked with a difunctional linker molecule. Pure encapsulated SWNTs (e-SWNTs) can then be separated from empty cross-linked micelles by consecutive cycles of centrifugation and redispersion. Atomic force and transmission electron microscopies of the resulting nanostructures demonstrate that individual nanotubes (rather than bundles) have been completely encased in polymer shells whose thickness is slightly larger than that of empty micelles. e-SWNTs encapsulated in PS-b-PAA can be permanently redispersed in H2O, in organic solvents, and in both hydrophobic and hydrophilic polymer matrices with minimal sonication. Micelle encapsulation could improve the compositing of SWNTs in a wide variety of polymer materials for structural, electronic, and thermal applications.
我们报道了一种通过将单壁碳纳米管（SWNTs）封装在交联胶束中来使其分散于溶剂和聚合物材料中的通用方法。由两亲性嵌段共聚物聚苯乙烯-嵌段-聚丙烯酸（PS-b-PAA）制成的胶束，首先通过向纳米管在二甲基甲酰胺中的悬浮液中逐渐加入水，围绕SWNTs进行组装。然后，这些胶束的亲水性外壳用双官能连接分子进行化学交联。然后，通过连续的离心和再分散循环，可以将纯的封装SWNTs（e-SWNTs）与空的交联胶束分离。对所得纳米结构进行的原子力显微镜和透射电子显微镜观察表明，单个纳米管（而非管束）已完全被聚合物壳包裹，聚合物壳的厚度略大于空胶束的厚度。封装在PS-b-PAA中的e-SWNTs在最少的超声处理下即可永久地再分散于水中、有机溶剂中以及疏水性和亲水性聚合物基质中。胶束封装可以改善SWNTs在各种聚合物材料中的复合，用于结构、电子和热学应用。
