Nitroxide-mediated radical polymerizations of 4-vinylpyridine and sodium 4-styrenesulfonate were carried out on the surfaces of MWNT to afford poly(4-vinylpyridine)-grafted MWNT (MWNT-P4VP) and poly(sodium 4-styrenesulfonate)-grafted MWNT (MWNT-PSS). The covalent bonding of polymers to the MWNT surface was confirmed by IR and TGA investigations. SEM, TEM and AFM investigations also showed a polymer-wrapped MWNT structure. Due to the presence of basic pyridine units in the structures, MWNT-P4VP exhibited good solubility in acidic aqueous solutions, but tended to aggregate in neutral or basic solutions. In comparison, MWNT-PSS could form stable dispersion solutions in aqueous solutions throughout the pH range from 1 to 14.
在MWNT表面进行了
4-乙烯基吡啶和4-
苯乙烯磺酸钠的硝基自由基聚合,得到聚(
4-乙烯基吡啶)接枝MWNT(MWNT-P4VP)和聚(4-
苯乙烯磺酸钠)接枝MWNT(MWNT-PSS)。通过红外光谱和热重分析证实了聚合物与MWNT表面的共价键合。扫描电子显微镜、透射电子显微镜和原子力显微镜的研究也表明了聚合物包裹的MWNT结构。由于结构中存在碱性
吡啶单元,MWNT-P4VP在酸性
水溶液中具有良好的溶解性,但在中性或碱性溶液中容易聚集。相比之下,MWNT-PSS可以在pH值为1至14的
水溶液中形成稳定的分散溶液。