Electric-Field-Induced Nanoscale Surface Patterning in Mexylaminotriazine-Functionalized Molecular Glass Derivatives

Abstract

Nanoscale surface patterns were observed in thin films of mexylaminotriazine-functionalized glasses containing polar groups upon the application of an electric field at temperatures over their glass transition temperatures (Tg). This phenomenon occurred due to the surface deformation process initiated by external electric field instabilities on the films. The minimal surface deformation temperature (Tdewet) relative to Tg was found to increase as a function of the polarity of the substituents and the surface pattern roughness was observed to increase linearly with temperature for a fixed electric field and exposure time. Reversal of the electrical field polarity and the use of both hydrophilic and hydrophobic substrates did not significantly change the surface deformation behavior of the films, which is due to the deposition of charges at the free interface. The application of a mask between the electric field electrodes allowed to selectively pattern areas that are exposed. Furthermore, it was observed that this surface deformation behavior was reversible, since heating the films to a temperature above Tg in the absence of an electric field caused the erasure of all surface patterns.

Enhancement of the Power Conversion Efficiency of Organic Solar Cells by Surface Patterning of Azobenzene Thin Films

“…In Figure 3a,b, it can be seen that heating an unbleached azobenzene molecular glass thin film above its 71 °C glass transition temperature 35 results in total erasure of the crossed gratings by allowing the azobenzene chromophores to relax back to their trans isomers. 36 However, as shown in Figure 3c,d, a 20 h UV treatment resulted in thermal stability of the nanostructures, with the rms roughness and maximum height of the nanostructures R q / R qmax of the film measured at 4.6/53 nm before heating and 5.1/57 nm after heating. While the thermal stability of UV-treated azobenzene structures has been previously observed for maleimide-based copolymers bearing azobenzene moieties, 31 a copolymer of 4′-[(2-(methacryloyloxy)ethyl) ethylamino]-4-nitroazobenezene with 2 methacryloyloxy-phenol (polyDR1M), 32 and an amorphous polymer containing Disperse Red 1 (DR1) and cross-linkable acrylic groups as separate side groups, 40 this thermal stability effect has never been reported for the newer gDR1 compound used in this work.…”

Unraveling the nucleation and growth of spontaneous surface relief gratings

“…These procedures and the mechanisms accounting for their respective dewetting behavior have been reported in previous studies. 22,23 Initial average RMS surface roughness for films prepared under these conditions are listed in Table 1. DR1-glass samples poled at 75 ºC for 30 minutes yielded films that contained a surface defect density similar to that observed during the initial irradiation with the writing beam.…”

“…The surface roughness of DR1-glass films could be increased by using corona poling using a process described in the literature. 23 Samples were annealed at various temperatures above their glass transition temperatures (Tg) while an electric field was applied. Temperature was controlled using Cole-Parmer Digi-Sense temperature controller and a hot plate.…”

State- and water repellency-controllable molecular glass of pillar[5]arenes with fluoroalkyl groups by guest vapors

“…Until now, only photo-responsive molecular glass with an azobenzene group showing an amorphous–crystalline transition has been reported. 11 …”