Shin Kyusoon, Obukhov Sergei, Chen Jiun-Tai, Huh June, Hwang Yoontae, Mok Soonchun, Dobriyal Priyanka, Thiyagarajan Pappannan, Russell Thomas P
School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, South Korea.
Nat Mater. 2007 Dec;6(12):961-5. doi: 10.1038/nmat2031. Epub 2007 Oct 14.
Non-classical behaviour, brought about by a confinement that imposes spatial constraints on molecules, is opening avenues to novel applications. For example, carbon nanotubes, which show rapid and selective transport of small molecules across the nanotubes, have significant potential as biological or chemical separation materials for organic solvents or gaseous molecules. With polymers, when the dimensions of a confining volume are much less than the radius of gyration, a quantitative understanding of perturbations to chain dynamics due to geometric constraints remains a challenge and, with the development of nanofabrication processes, the dynamics of confined polymers have significant technological implications. Here, we describe a weak molecular-weight-dependent mobility of polymers confined within nanoscopic cylindrical pores having diameters smaller than the dimension of the chains in the bulk. On the basis of the chain configuration along the pore axis, the measured mobility of polymers in the confined geometry is much higher than the mobility of the unconfined chain. With the emergence of nanofabrication processes based on polymer flow, the unexpected enhancement in flow and reduction in intermolecular entanglements are of significant importance in the design and execution of processing strategies.
由对分子施加空间限制的 confinement 所引发的非经典行为，正在为新型应用开辟道路。例如，碳纳米管能使小分子在纳米管间快速且选择性地传输，作为有机溶剂或气态分子的生物或化学分离材料具有巨大潜力。对于聚合物，当限制体积的尺寸远小于回转半径时，定量理解几何约束对链动力学的扰动仍是一项挑战，并且随着纳米制造工艺的发展，受限聚合物的动力学具有重大的技术意义。在此，我们描述了限制在直径小于本体中链尺寸的纳米级圆柱形孔内的聚合物的弱分子量依赖性迁移率。基于沿孔轴的链构型，在受限几何结构中测得的聚合物迁移率远高于非受限链的迁移率。随着基于聚合物流动的纳米制造工艺的出现，流动的意外增强和分子间缠结的减少在加工策略的设计和实施中具有重要意义。
