Mechanical Characterization of Polymeric Thin Films Using Nano Cutting Method

In the ultra-precision industry, physical and chemical coatings are used to provide functional properties to the surface. Especially, it is very important to examine the mechanical durability of polymer thin films with super hydrophobic properties. The mechanical durability of the thin film includes adhesion force and shear strength, and the latter can be measured with precise cutting. A sharp blade capable of changing cutting direction is used for cutting nano-thick films. Then, nano cutting method is used to calculate the shear strength by measuring the resistant forces when the blade cuts thin films simultaneously in the horizontal and vertical directions (slanted cutting). In this study, we prepared two super-hydrophobic fluoropolymers, p(PFDMA) (1H, 1H, 2H, 2H-perfluorodecyl methacrylate) thin film and p(V4D4-PFDMA-co-DVB) thin film, using initiated chemical vapor deposition method. Especially, p(V4D4-PFDMA-co-DVB) thin film was obtained by continuous deposition with V4D4 (1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) and DVB (CH(CH=CH), divinylbenzene) in order to improve its durability, and the abrasion test was performed to quantitatively check the durability. In order to qualitatively assess the durability, the thin film was cut with a customized precision-cutting tool, and the shear strength and adhesion force were analyzed. As a result, it was confirmed that the mechanical durability of p(V4D4-PFDMA-co-DVB) thin film has dramatically improved compared to p(PFDMA) thin film. In addition, the nano cutting theory was successfully verified to evaluate the mechanical properties of thin films.