8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.170Wed 711:10-14:00Holographic microscopy for self-organizing functionalmaterials of biomimetic folding particle chainsPeter van Oostrum, 1 Arnout Imhof, 2 Erik Reimhult, 3 Alfons van Blaaderen, 4 IvanColuzza, 5 Hanumantha Rao Vutukuri, 2 and Ronald Zirbs 11 BOKU - DNBT, Muthgasse 11-II, 1090, Vienna, Austria2 Utrecht University, Utrecht, Netherlands3 University of Natural Resources and Life Sciences (BOKU) Vienna, Vienna,Austria4 Soft Condensed Matter Group, Debye Institute for NanoMaterials Science, UtrechtUniversity, Utrecht, Netherlands5 University of Vienna, Vienna, AustriaOur goal is to experimentally realize directed self-assembly of colloid chains through self-folding.This concept is inspired by how the sequence of differently interacting amino acids in proteinsdetermines their folded 3-D structure. We are inspired to achieve the same on the colloidal scaleand follow a recent theory for directed self-folding of colloidal chains, which prescribes that selffoldingcan be engineered for strings of particles interacting over multiple radii and including adirectional (patchy) interaction potential. We present the first steps towards realization of thisconcept and in particular the use of digital holographic microscopy (DHM) to track particles in3D. The incandescent illumination of a standard light microscope is replaced by a laser beam. Werecord in-line holograms by recording the magnified interference pattern between scattered lightand the background illumination. During post processing, we numerically minimize the differencebetween simulated and experimental holograms to measure the particle positions in 3D. This waywe routinely obtain nm resolution in 3D at video rates, from which we can measure the interparticleinteractions. We demonstrate that this technique can also work for strings of particlesformed by induced dipolar interactions using dielectric trapping with applied AC fields. Colloidswith extremely high molecular weight dendronic polymer shells are used to produce the desiredlong-range interactions. We present some first results from synthesis and characterization of suchparticles as ”monomer libraries” for the self-folding chains. Particular focus will be given to theuse of DHM to measure the interaction potentials of the core-shell particles in the presence of largedepletants to control the pair-interactions.170