Photoinduced Phase Separation of a Mixed Film of a Photochromic Amorphous Molecular Material and a Quaternary Ammonium Salt

Abstract

Phase separation of the mixed film of an azobenzene-based photochromic amorphous molecular material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene, and a quaternary ammonium salt, tetrabutylammonium tetrafluoroborate, could be induced to form dissipative self-assembled microstructures not only by heating but also by photoirradiation. Fabrication of a micropattern and a relief grating composed of the quaternary ammonium salt by irradiation of the film followed by rinsing with hexane was demonstrated. The present study indicates that the mixed films of amorphous molecular materials and quaternary salts are novel candidates for micro- and nano-patterning materials.

Phase Separation of Mixed Films of Amorphous Molecular Materials with Quaternary Ammonium Salts: 4,4',4"-Tri(phenothiazinyl)triphenylamine-Tetrabutylammonium Tetrafluoroborate System

“…The results suggested that the main components of the circular domains and their periphery were TBABF 4 and TPTTA, respectively. It is notable that the diameter of the circular domain observed in the present study was almost similar to that for TBABF 4 -BFlAB system [12]. Therefore, the diameter of the circular domain was supposed to be determined irrespective of the kind of the amorphous molecular material.…”

“…The extrapolation of the plots of the number density of circular domains vs. the concentration of the TBABF 4 suggests that the concentration of TBABF 4 in the peripheral phase was ca. 5 mol%, being larger than that for TBABF 4 -BFlAB system [12]. …”

“…We have previously reported that the mixed amorphous film of 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene (BFlAB) and tetrabutylammonium tetrafluoroborate (TBABF 4 ) exhibited phase separation to produce dissipative pattern by annealing at ca. 160 °C [12]. In addition, we have shown that phase separation of the film could be induced by photoirradiation and surface relief grating composed of TBABF 4 could be fabricated by irradiation of the mixed amorphous film with coherent laser beams followed by rinsing with hexane.…”

Photoinduced Change in Phase-Separated Structure of a Binary Film Composed of 4-[Bis(9,9-dimethylfluoren-2-yl)amino]-4'-nitroazobenzene and Poly(vinyl acetate)

“…In addition to the above single component systems, we have also investigated photomechanical behaviors observed for binary systems. We have reported that the mixed film of 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene (BFlAB) and a quaternary ammonium salt exhibited photoinduced phase separation and that SRG composed of the quaternary salt could be obtained by interference irradiation of the mixed film followed by immersing to hexane [28]. In addition, we have reported the preliminary results of photomechanical effect observed for binary films of BFlAB and poly(vinyl acetate) (PVAc) obtained by spin-coating method [ 29 ].…”

Emission Modulation of Poly(vinyl acetate)-Tetrabutylphosphonium Tetrafluoroborate Hybrid Film Doped with 4-[Bis(4-methylphenyl)amino]-benzaldehyde

“…In contrast, we have recently started studies on photofunctional hybrid systems that include low molecular-mass component. For instance, hybrid films composed of azobenzene-based photochromic amorphous molecular materials, namely low molecular-mass photochromic materials that readily form amorphous glasses, and quaternary ammonium and phosphonium salts were found to exhibit phase separation to form dissipative self-assembled microstructures not only by heating but also by photoirradiation [6]. We have also found that hybrid films of azobenzenebased photochromic amorphous molecular materials and poly(vinyl acetate) (PVAc) exhibited thermally reversible phase-separation-dissolution transitions and that the structure of domains produced in the phase-separated film could be deformed by irradiation with polarized laser beam [7].…”