Altering surface fluctuations by blending tethered and untethered chains.
Altering surface fluctuations by blending tethered and untethered chains.
复制标题
通过混合系链和非系链来改变表面波动。
作者：
J. K. Lee;B. Akgun;Z. Jiang;S. Narayanan;M. Foster
通过将未缠结熔体中的一部分链共价连接到基底上来“部分束缚”聚合物熔体的薄膜，显著增加了表面高度波动的弛豫时间。即使当膜厚度h是系链的未扰动链半径Rg的20倍时也观察到这种现象，表明部分系链比与基材的任何物理吸引力更有影响力。此外，5k的低平均分子量的部分束缚层显示出比大得多的分子量（48k）的纯未束缚链的参考层慢得多的表面波动，因此部分束缚效应比缠结效应和玻璃化转变温度Tg随分子量增加的效应更强。部分系留提供了一种调整这些波动的手段，这些波动影响表面的润湿性、粘附性和摩擦学。
"Partially tethering" a thin film of a polymer melt by covalently attaching to the substrate a fraction of the chains in an unentangled melt dramatically increases the relaxation time of the surface height fluctuations. This phenomenon is observed even when the film thickness, h, is 20 times the unperturbed chain radius, Rg,tethered, of the tethered chains, indicating that partial tethering is more influential than any physical attraction with the substrate. Furthermore, a partially tethered layer of a low average molecular weight of 5k showed much slower surface fluctuations than did a reference layer of pure untethered chains of much greater molecular weight (48k), so the partial tethering effect is stronger than the effects of entanglement and increase in glass transition temperature, Tg, with molecular weight. Partial tethering offers a means of tailoring these fluctuations which influence wetting, adhesion, and tribology of the surface.