The lower surface free energy achievements from ladder polysilsesquioxanes with fluorinated side chains

The surface free energy of non-F and F-containing ladder polyepoxysilsesquioxanes was calculated by two- and three-liquid methods based on contact angle measurements. These ladder polyepoxysilsesquioxanes exhibited lower surface free energy (<17 mJ/m2) because of their main chain packing on the surface of the films where the side chain alignment was promoted by their ladder structure. And the surface free energy of the polyepoxysilsesquioxanes could be reduced further by the incorporation of perfluoroalkyl group into the side chains (∼13 mJ/m2). The X-ray diffraction results revealed that the F-containing side chain lead to the ladder main chain much more flattening on the surface of the films, explaining the contributions of side and main chain arrangements to the surface free energy.

Graphical abstractThe ladder would lay flat on the surface of wafer. The side chain could align on the surface of the wafer according to the orientation of ladder, leading to a film surface composed of molecular tails. When the liquid was dropped on the surface of the films, some of the drops were suspended in the air by these molecular side chains; some small “voids” were left and the air were trapped on the surface. The combined chemical variation of the polymer and surface roughness of the film contributed to the lower surface energy. Figure optionsDownload full-size imageDownload as PowerPoint slide