“Smart” Surface Dissymmetrization of Microparticles Driven by Laser Photochemical Deposition

Abstract

Dissymmetric nano/microsized spheres are very appealing because controlled dissymmetry brings an additional degree of freedom for the synthesis of a new generation of materials with spatially separated chemical properties. We explore this aspect by extending to spherical surfaces the application field of lithographic techniques that was up to now essentially limited to planar and cylindrical substrates. The method proposed uses a strongly focused laser beam to generate dissymmetric coatings on microparticles by micro-photochemical deposition in a reactive solution. This is experimentally illustrated by considering the photochemical reduction of chromate ions induced by a continuous Ar + laser wave to "nucleate" and grow a dissymmetry on the surface of silica beads dispersed in a chromate solution. When properly rescaled, the coating growth laws measured at different laser excitations are reduced to a single master behavior that implies a simple strategy to control and predict the desired dissymmetry from its dynamics. The versatility of the technique is then demonstrated by scanning the beam (i) to tailor microscale patterning on one hemisphere and (ii) to assemble beads into ordered structures. Owing to its flexibility, the method can easily be extended to the coating of different types of particles and various photochemical reactions.

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…In addition, there are directional methods that are being used to form chemical patches on surface of particles such as microcontact printing [387][388], etching [389], laser- [390] or UV-induced deposition [391], projection lithography [392], metal deposition [393][394] and temporary masking one side of particles while modifying the other [395][396]. Most of these methods are waiting to be explored for porous particles.…”

Spatioselective Modification of Bicompartmental Polymer Particles and Fibers via Huisgen 1,3‐Dipolar Cycloaddition

“…The increasing emphasis on anisotropic phenomena has been partially driven by the introduction of novel synthetic concepts for a range of different anisotropic materials 7, 8. For instance, methods of synthesizing anisotropic particles include the use of a spinning disk,9, 10 self‐assembly,11, 12 fusion of pre‐existing particles,13 surface modification with partial masking,14–17 selective deposition,18, 19 surface modification through partial contact with reactive media,20–22 microcontact printing23, 24 and template‐assisted self‐assembly,25, 26 flow‐focusing lithography27–29 or microfluidic techniques 30–33. An alternative strategy towards anisotropic micro‐ and nanoparticles uses electrohydrodynamic co‐jetting 34–36.…”

Dissymmetrization of micro-particle surface by laser-induced photochemical deposition

“…Cr III , used in dichromated gelatins for optical recording [ 13 ], the experiment, shown in Figure 1, is based on the photochemical deposition of a chromium oxide layer [ 14 ]. It is performed at room [13], see Eq.…”