Surface analysis of plasma‐treated polydimethylsiloxane by x‐ray photoelectron spectroscopy and surface voltage decay

Nanocontact Electrification through Forced Delamination of Dielectric Interfaces

“…To determine if material transfer played an important role, we conducted several atomic force microscopy (AFM) and X-ray photon spectroscopy (XPS) studies (shown in Supporting Information Figure S1). We found no measurable material transfer between plasma treated PDMS and untreated PMMA, which is consistent with prior XPS studies by others. − Yet PMMA charges highly upon contact, as shown in Supporting Information Figure S2. In the case of SiO 2 , things are more complicated and are more sensitive to the details of oxygen plasma treatment.…”

“…PDMS was chosen as the primary contacting material and was either patterned in topography through molding , to provide small contact areas surrounded by unchanged surface areas or it was left flat to lay down a uniform layer of charge. To clean and activate the PDMS surface (Figure a), we used a pure oxygen plasma etcher (SPI Plasma Prep II) operating at 80−100 W at 10 Torr for 40 s. This process is used because it creates an energetic, hydrophilic surface that reduces transfer of uncured material during contact when compared to untreated PDMS. − Untreated PDMS did not result in high levels of charge transfer. As electrets, we tested PMMA and SiO 2 .…”

“…The working hypothesis for the charging mechanism is illustrated in Figure c and involves hydrogen proton exchange at the interface. It is known that plasma treatment attacks the Si-CH 3 bonds on the surface of the PDMS, leaving very reactive silyl radicals that capture O, OH, COOH, and oxygen radicals, forming a mildly acidic and highly polar surface. , PMMA on the other hand can be considered as being “less acidic” than plasma treated PDMS because it contains fewer surface hydrogen atoms. This creates a chemical potential difference that allows hydrogen protons to transfer during contact.…”

Hierarchical Pore Structures Fabricated by Electron Irradiation of Silicone Grease and their Applications to Superhydrophobic and Superhydrophilic Films

“…All the XPS spectra were charge compensated to C 1s at 284.6 eV. [16] The surfaces of the electron-irradiated films were chemically modified to get superhydrophobicity or superhydrophilicity. For superhydrophobicity, the irradiated films were treated with a low surface energy material of fluorosilane ((heptadecafluoro-1,1,2,2-tetrahydrodecyl) trichlorosilane) (Alfa Aesar); the samples were immersed in a hexane solution of 20 Â 10 À3 M fluorosilane for 30 min and dried at room temperature.…”

Fabrication of a Multidomain and Ultrafast‐Switching Liquid Crystal Alignment Layer Using Contact Printing with a Poly(dimethylsiloxane) Stamp

“…For this PDMS thin film layer with a randomly coiled conformation, the LC alignment direction was perpendicular to the surface and vertical LC behavior was exhibited (as shown in the left‐hand inset of Figure 2d), because of nonpolar intermolecular interaction between the terminal methyl (–CH 3 ) groups of randomly coiled chains and the side chains of the LC molecules. Indeed, the intrinsic properties of a general PDMS thin layer induce the vertical LC configuration 11, 22. However, the PDMS SAO alignment layer showed a planar homogeneous alignment of the LCs (as shown in the left‐hand inset of Figure 2f).…”