Polymer Grafting to Single-Walled Carbon Nanotubes: Effect of Chain Length on Solubility, Graft Density and Mechanical Properties of Macroscopic Structures

Single-walled carbon nanotubes are grafted with polystyrene chains employing a graft-to protocol. Thermogravimetric analysis allows calculation of the grafted chain density and average interchain separation on the nanotube surface as a function of molecular weight. The separation scales with molecular weight as a power law with an exponent of ca. 0.588, showing the grafted chains to be in a swollen random walk conformation. This implies that chain packing is controlled by coil size in solution. In addition, the dispersed concentration of functionalized nanotubes scales with the size of the steric potential barrier that prevents aggregation of polymer functionalized nanotubes. It is also shown that the molecular weight of the grafted chains significantly affects the mechanical properties of nanotube films.

采用接枝到（graft - to）方法将聚苯乙烯链接枝到单壁碳纳米管上。热重分析能够计算出纳米管表面接枝链的密度以及平均链间间距随分子量的变化。间距与分子量呈幂律关系，指数约为0.588，表明接枝链呈溶胀的无规行走构象。这意味着链的堆积受溶液中链圈尺寸的控制。此外，功能化纳米管的分散浓度与防止聚合物功能化纳米管聚集的空间位阻势垒大小有关。还表明接枝链的分子量显著影响纳米管薄膜的机械性能。