Relaxation Kinetics of Nanostructures on Polymer Surface: Effect of Stress, Chain Mobility, and Spatial Confinement
Relaxation Kinetics of Nanostructures on Polymer Surface: Effect of Stress, Chain Mobility, and Spatial Confinement
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DOI：
10.1021/ma901666v
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发表时间：
2010-01
期刊：
影响因子：
5.5
通讯作者：
H. Peng;Y. Kong;A. Yee
中科院分区：
文献类型：
--
作者：
H. Peng;Y. Kong;A. Yee
利用纳米压印技术在聚苯乙烯表面制备了小至33 nm的线光栅，研究了聚合物纳米结构在释放空间约束后的弛豫和链动力学。对于所有分子质量（MWs），“塌缩”（线高快速松弛）的温度随着线宽的减小而降低，但基于表面迁移率增强的简单解释无法解释结果。当分子量较低且结构较大时，AFM监测的线高随着表面张力克服聚合物粘度而降低。当聚合物分子的旋转半径（Rg）与纳米结构的尺寸相比不小时，可以观察到有趣而复杂的行为。对表面粘度的仔细研究表明，将聚合物链限制在与其Rg相当甚至更小的空间中，似乎可以增强弛豫，这是高MW纳米结构在惊人的低温下坍塌的主要因素。
Relaxation and chain dynamics of polymer nanostructures after release of spatial confinement were studied using line gratings as small as 33 nm on polystyrene surface fabricated by nanoimprint lithography. The temperature for “slumping”—rapid line height relaxation—decreased as the line width diminished for all molecular masses (MWs), but a simple explanation based on enhanced surface mobility fails to explain the results. When MW was low and the structure was large, the line height monitored with an AFM reduced as surface tension overcame the polymer viscosity. Interesting and complex behaviors were observed when the radius of gyration (Rg) of the polymer molecules was not small compared with the dimension of the nanostructure. Careful examination of the surface viscosity shows that confinement of polymer chains into space comparable to or even smaller than its Rg appears to enhance relaxation, which is the major factor for the surprisingly low temperature at which nanostructures of high MW slumps.