Surface-Initiated Mechanism for the Formation of Relief Gratings on Azo-Polymer Films

Abstract

We report here a detailed experimental study, establishing the surface-initiated mechanism for the photoinduced relief grating formation on azobenzene functionalized polymer films. The grating formation process is found to be strongly dependent on the nature of the surface (20−200 Å), while the birefringent grating appears to be a purely bulk process. Restriction of the surface of the azobenzene polymer film through the deposition of ultrathin top layers of transparent polyelectrolytes by electrostatic self-assembly dramatically decreases the relief grating formation. Thicker polyelectrolyte multilayer film (250 Å) on the surface resulted in the formation of purely birefringent grating, without any surface features.

Ultrathin polymer coatings by complexation of polyelectrolytes at interfaces: suitable materials, structure and properties

“…The diverse suggestions comprise the use for compatibilization and protection of surfaces 68,351,362,363,366,383,384) , as well as (bio)sensors 26, 59, 69, 70, 209, 237, 238, 256, 298, 299, 315, 334-338, 341, 350, 354-358, 395) , enzyme immobilization 108, 109, 155, 267, 340, 346-349, 361, 372) , and gene transfection 342) . Other potential applications are separation membranes and chromatography columns 66,99,187,192,319,369,370,402,405,414) , conducting, lightemitting or photovoltaic devices 91, 112, 151-154, 165-167, 170-182, 185, 186, 194, 197, 200, 270-273, 277, 285, 296, 322, 328, 453) high charge density batteries 287,321,325) , modified electrodes 196,209,454) , orientation layers 88,89) , optical data storage and magnetic films 42,67,72,110,120,275,436) , or controlled particle and catalyst preparation 71,420,436) . If spherical supports are used which may be dissolved by a secondary process, hollow spheres are accessible which have been suggested for encapsulation and drug delivery 42,258,…”

Volume generation towards dynamic surface morphing in liquid crystal polymer networks

“…A number of groups [20][21][22][23] have demonstrated the generation of surface relief gratings in thin films by using azobenzene-containing polymers. Gratings are fabricated by mass transport of polymer chains by continuous isomerisation of the azobenzene unit under a single beam of polarised light [24][25][26].…”

Quantum Chemical Design of Light Driven Molecular Logical Machines

“…More flexible is -N=N-bridge and therefore all kinds of azo-dye molecules convert almost all photo-excitation energy to trans-cis isomerization energy [19][20][21]. We expect that in the case the OR logic device (see FigA) of our design, should be deposited on the solid surface then, due to the per linear trans-cis and cis-trans reorganizations which we have authored, (see [22,23] and chapter above) the photoinduced energy should be converted to movements of OR logic device.…”

“…A detailed experimental studies, establishing the surfaceinitiated mechanism for the photoinduced relief grating formation on azobenzene functionalized polymer films, were performed by P.L. Rochon et at [19], S. K. Triphaty et at [20] and J.-M. Nunzi et at [21] that are used for optical information storage devices. However, the mechanism of isomerization of the azo-dye derivatives still has not been properly understood.…”