Steric Forces of Tethered Polymer Chains as a Function of Grafting Density: Studies with a Single Diblock Molecular Weight
Steric Forces of Tethered Polymer Chains as a Function of Grafting Density: Studies with a Single Diblock Molecular Weight
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DOI：
10.1021/ma3009146
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发表时间：
2012-07-24
期刊：
影响因子：
5.5
通讯作者：
Kuhl, Tonya L.
中科院分区：
文献类型：
--
作者：
Liao, Wei-Po;Kuhl, Tonya L.
使用表面力装置测量作为接枝密度的函数的压缩相对聚合物刷的法向力。与通过改变聚合物分子量来改变接枝密度的常规方法相反，在这项工作中，通过旋涂不同浓度的单一二嵌段共聚物来获得范围为1.4至7.6 mg/m2的高接枝密度。在低接枝密度（σ < 4 mg/m2）下测得的力分布与先前的研究类似，并且一旦考虑到链的多分散性，则与Milner-Witten-Cates（MWC）理论预测一致。在较高的接枝密度，实验测得的排斥相互作用能或力显示出缩放行为的无量纲力曲线落在彼此的顶部，然而，该行为是明显不同的低接枝密度制度，不能使用理论开发的稀/半稀制度。
The normal force to compress opposing polymer brushes as a function of grafting density was measured using a surface force apparatus. In contrast to conventional methods where grafting density has been varied by changing polymer molecular weight, in this work high grafting densities ranging from 1.4 to 7.6 mg/m(2) were obtained by spin-coating different concentrations of a single diblock copolymer. Measured force profiles at low grafting density, sigma < 4 mg/m(2), were analogous to previous studies and consistent with Milner-Witten-Cates (MWC) theoretical predictions once chain polydispersity was accounted for. At higher grafting densities the experimentally measured repulsive interaction energy or force showed scaling behavior where the nondimensionalized force curves fall on top of each other; however, the behavior is distinctly different from the low grafting density regime and cannot be modeled using theory developed for the dilute/semiclilute regime.