Nguendia Jules Zeuna, Zhong Weiheng, Fleury Alexandre, De Grandpré Guillaume, Soldera Armand, Sabat Ribal Georges, Claverie Jerome P
Quebec Center for Functional Materials, NanoQAM, Department of Chemistry, Université du Québec à Montréal, Succ. Centre-Ville, CP8888, Montreal, H3C3P8 Qc (Canada).
Chem Asian J. 2014 May;9(5):1356-64. doi: 10.1002/asia.201301687. Epub 2014 Mar 5.
Copolymers of 2-ethylhexyl acrylate (EHA) and cholesteryloxycarbonyl-2-hydroxymethacrylate (CEM) were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Supramolecular complexes of these copolymers with carbon nanotubes (CNTs) were soluble in THF, toluene, and isooctane. The colloidal solutions remained stable for months without aggregation. The rationale for the choice of CEM was based on the high adsorption energy of cholesterol on the CNT surface, as computed by DFT calculations. Adsorption isotherms were experimentally measured for copolymers of various architectures (statistical, diblock, and star copolymers), thereby demonstrating that 2-5 cholesterol groups were adsorbed per polymer chain. Once the supramolecular complex had dried, the CNTs could be easily resolubilized in isooctane without the need for high-power sonication and in the absence of added polymer. Analysis by atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicated that the CNTs were devoid of bundles. The supramolecular complexes could also be employed in an inverse emulsion polymerization of 2-hydroxyethylmethacrylate (HEMA) in isooctane and dodecane, thereby leading to the formation of a continuous polymeric sheath around the CNTs. Thus, this technique leads to the formation of very stable dispersions in non-polar organic solvents, without altering the fundamental properties of the CNTs.
通过可逆加成-断裂链转移（RAFT）聚合法制备了丙烯酸2-乙基己酯（EHA）和胆固醇氧基羰基-2-甲基丙烯酸羟甲酯（CEM）的共聚物。这些共聚物与碳纳米管（CNT）形成的超分子复合物可溶于四氢呋喃、甲苯和异辛烷。胶体溶液可保持稳定数月而不发生聚集。选择CEM的依据是通过密度泛函理论（DFT）计算得出的胆固醇在碳纳米管表面的高吸附能。对各种结构的共聚物（无规共聚物、二嵌段共聚物和星形共聚物）进行了吸附等温线的实验测定，结果表明每条聚合物链上吸附有2 - 5个胆固醇基团。一旦超分子复合物干燥后，碳纳米管无需高功率超声处理且在不添加聚合物的情况下就能轻松地再次溶解于异辛烷中。通过原子力显微镜（AFM）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）分析表明，碳纳米管没有形成管束。这种超分子复合物还可用于甲基丙烯酸2-羟乙酯（HEMA）在异辛烷和十二烷中的反相乳液聚合，从而在碳纳米管周围形成连续的聚合物鞘层。因此，该技术可在非极性有机溶剂中形成非常稳定的分散体，且不会改变碳纳米管的基本性质。
