Colloidal Organization at interfaces Reconfigured by LIGHT-driven thermal Marangoni flows


CALL: 2018

DOMAIN: MS - New Functional and Intelligent Materials and Surfaces

FIRST NAME: Emmanouil

LAST NAME: Anyfantakis



HOST INSTITUTION: University of Luxembourg

KEYWORDS: optofluidics, colloidal dispersions, photothermal Marangoni flows, dynamic self-assembly, colloid, particle patterning, drop evaporation

START: 2019-01-01



Submitted Abstract

We propose to use light to manipulate and organize particles at fluid interfaces and solid surfaces, developing a method that is largely applicable to any choice of solvents, particles and substrates. With localized IR irradiation we will impose high resolution surface tension gradients at the free interfaces of the suspensions. This will allow us to control Marangoni flows in space and time, via two complementary photothermal mechanisms, which will be optimized for manipulating interfacial particles. The first one takes advantage of divergent thermocapillary flows due to the temperature dependence of air-liquid surface tension. The second one instead utilizes the convergent thermosolutal Marangoni flows due to enhanced co-solvent evaporation at irradiated areas of air-water/co-solvent interfaces. These flows will be the driving force for reversibly organizing particles of different types at fluid interfaces. We will explore the rich physics behind the interplay of hydrodynamics and interparticle interactions in this unique paradigm of light-driven dynamic self-assembly in 2D. Further, by tuning the flows and interparticle potential, we will be able to produce tailor-designed 2D structures. Finally, we will develop a unique method for particle patterning on solids at locations programmed by light, by implementing optically controlled convective flows developed in the bulk of colloidal suspensions due to Marangoni flows at their free interface. We will study the influence of flows and material parameters on the microstructure of the deposits. The feasibility of COReLIGHT is supported by our previous works, where we used photochemical flows to manipulate objects at fluid interfaces and for patterning nanoparticles on solids at UV-irradiated positions. Furthermore, in preliminary experiments, we recently observed that localized IR irradiation leads to strong surface flows that are able to move and rearrange the organization of particles at the air-water interface. From a fundamental viewpoint, COReLIGHT aims at shining light on the physical mechanisms of the coupling of flows and particle organization in both 2D and 3D. From an application perspective, our strategy drops the necessity of special light-responsive entities, extending its applicability to numerous colloids regardless of their specific properties.

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