Azobenzene-Containing Monolayer with Photoswitchable Wettability

Abstract

A compact monolayer containing azobenzene has been prepared on silicon substrates. The elaboration route consisted of covalent grafting of freshly synthesized azobenzene moieties onto an isocyanate-functionalized self-assembled monolayer (SAM). The highly packed and ordered isocyanate-functionalized SAM and the azobenzene-functionalized SAM were monitored and characterized by contact angle measurements and X-ray reflectivity (XR). Photoswitching of the wettability of the film induced by the reversible cis-trans isomerization of the azobenzene chromophores is experimentally shown from water and olive oil contact angle measurements.

Optical properties of azobenzene-functionalized self-assembled monolayers: Intermolecular coupling and many-body interactions

“…[1][2][3][4][5][6] Azobenzene-functionalized selfassembled monolayers (SAMs) of alkyl chains have been successfully synthesized in the last two decades. [7][8][9][10][11][12] Unfortunately, such systems come with a substantial drawback: The photo-isomerization rate is drastically suppressed due to steric hindrance or excitonic coupling. 13,14 A number of experimental strategies have been suggested to overcome this problem, such as replacing the aliphatic linker by an aromatic one 15 or even bulkier groups, [16][17][18] or diluting the azobenzene moieties in densely-packed alkanethiolate SAMs.…”

Vibrational analysis of [4-[(E)-phenylazo] phenyl]ethanol based on the comparison between the experimental and DFT calculated Raman spectra

“…Because of their unique characteristics [1] (spread over air-water interface [2,3], disperse into porous materials to form hybrid organic-inorganic composites [4][5][6], graft onto polymers chains [7][8][9] or onto inorganic materials and surfaces [10][11][12][13]) azobenzene and its derivatives have been of great interest over the past two decades. The azobenzene derivatives which exhibit photoisomerization from the thermodynamically more stable trans isomer to the cis isomer (and vice versa) by irradiation with UV or visible light were extensively studied for their photochemical properties in solution [1,14] and therefore for their ability to produce photochemical devices [16][17][18].…”

“…There has been a considerable worldwide research dedicated to their great potential for optical applications, including optical storage and holographic surface relief gratings [24][25][26][27], and active optical integrated circuits [28][29][30]. In recent years there have been increasing efforts toward the development of diverse azobenzene-based smart multifunctional materials [31][32][33][34] and the development of stimuli-responsive surfaces [12,[35][36][37][38].…”

Surface properties, thermal behavior, and molecular simulations of azo-polysiloxanes under light stimuli. Insight into the relaxation

“…surface relief gratings (SRGs) for holographic storage and optical switching, [7][8][9][10][11][12] in the field of the nanomanipulation of molecules, 13,14 those of the controlled drug delivery 5,6,15 and of the mechano-sensitive channels technology as well. 16 Moreover, due to the azo-groups dipole moment modification as a consequence of the transcis photo-isomerization process, polymers films having photoswitchable wettability can be obtained. [17][18][19][20][21] Under UV irradiation, the azobenzene planar trans isomer transforms into a bent and twisted cis-form, this process being reversed by photo-activation (VIS light) and/or thermal relaxation.…”