writer：Xu Li, Xiaolin Lu*
keywords：irreversibly adsorbed layer, dewetting, SFG, PS film
source：期刊
specific source：Macromolecules, 2018, 51 (17), pp 6653–6660.
Issue time：2018年

和频振动光谱和光学显微实验显示，对高分子薄膜热处理的过程即为基底界面上形成不可逆吸附高分子链层的过程。随着热处理的进行，这一层高分子继续演化，包括单一吸附的高分子链形成更多的吸附位点，界面上形成的Trains发生局部的松弛过程。我们直接关联和证实，这一层不可逆吸附的高分子链层促进了其上薄膜自憎去润湿的发生。

https://pubs.acs.org/doi/full/10.1021/acs.macromol.8b01141

Dewetting of a polymer thin film is directly correlated to the interface with the substrate. We thus, combined sum frequency generation (SFG) vibrational spectroscopy and laser scanning confocal microscopy (LSCM) to trace both the interfacial molecular structural and macroscopic morphological evolutions of the polystyrene (PS) thin film on top of the sapphire substrate upon annealing, till happening of dewetting. To reveal the molecular structure of the irreversibly adsorbed layer over the annealing time, a solvent-leaching method was adopted to uncover it from the polymer thin film on the substrate. Experimental results demonstrate, the local structural evolution of the irreversibly adsorbed layers, including replacement of adsorption sites (trains sequences) from different chains to those from single chains and local structural relaxation of the trains sequences, significantly promoted the dewetting. The dewetting of the PS thin film was actually accompanied with such structural evolution of the irreversibly adsorbed layer. We believe, this experimental investigation on highlighting the irreversibly adsorbed layer can provide the molecular level insight on how the macroscopic dewetting happens for a polymer thin film on a substrate.