Kienle Sandra, Gallei Markus, Yu Hao, Zhang Baozhong, Krysiak Stefanie, Balzer Bizan N, Rehahn Matthias, Schlüter A Dieter, Hugel Thorsten
Physik Department E22 and IMETUM, Technische Universität München , 85748 Garching, Germany.
Langmuir. 2014 Apr 22;30(15):4351-7. doi: 10.1021/la500783n. Epub 2014 Apr 8.
Several applications require strong noncovalent adhesion of polymers to substrates. Graft and branched polymers have proven superior to linear polymers, but the molecular mechanism is still unclear. Here, this question is addressed on the single molecule level with an atomic force microscopy (AFM) based method. It is determined how the presence of side chains and their molecular architecture influence the adhesion and the mobility of polymers on solid substrates. Surprisingly, the adhesion of mobile polymers cannot significantly be improved by side chains or their architecture. Only for immobile polymers a significantly higher maximum rupture force for graft, bottle-brush, and branched polymers compared to linear chains is measured. Our results suggest that a combination of polymer architecture and strong molecular bonds is necessary to increase the polymer-surface contact area. An increased contact area together with intrachain cohesion (e.g., by entanglements) leads to improved polymer adhesion. These findings may prove useful for the design of stable polymer coatings.
几种应用需要聚合物与基底之间有很强的非共价粘附力。接枝聚合物和支化聚合物已被证明优于线性聚合物，但其分子机制仍不清楚。在此，利用基于原子力显微镜（AFM）的方法在单分子水平上解决了这个问题。确定了侧链的存在及其分子结构如何影响聚合物在固体基底上的粘附力和流动性。令人惊讶的是，侧链或其结构并不能显著提高可移动聚合物的粘附力。只有对于不可移动的聚合物，与线性链相比，接枝聚合物、刷状聚合物和支化聚合物的最大断裂力显著更高。我们的结果表明，聚合物结构和强分子键的结合对于增加聚合物-表面接触面积是必要的。增加的接触面积与链内内聚力（例如通过缠结）一起导致聚合物粘附力的提高。这些发现可能对稳定聚合物涂层的设计有用。
