Monday, 10 October 4:00pm – 5:00pm

This seminar will be delivered in Chemistry Lecture Theatre 4 and Online Zoom. Please email chemistry.researchsupport@sydney.edu.au for zoom link and password.

Speaker: Dr Dan Daniel; Institute of Materials Research and Engineering, A*Star, Singapore

Host: Prof. Chiara Neto

Title: Probing surface wetting across multiple force, length and time scales

Abstract: Surface wetting is a multiscale phenomenon where properties at the macroscale are determined by processes at much smaller length scales, such as nanoscale surface topographies. Traditionally, the wetting of surfaces is quantified by the macroscopic contact angle that a liquid droplet makes. Contact angle measurement remains useful but suffers from various limitations. For example, contact angles are difficult to determine accurately for large values or when surfaces are rough. Moreover, they cannot capture the local wetting variations due to chemical heterogeneities or surface textures.

Our lab has developed several techniques to address these shortcomings. By attaching a millimetric droplet to a cantilever-based force sensor or a micrometric droplet to an atomic force microscope (droplet probe AFM), we are able to directly measure droplet-surface interactions forces (from uN to sub-nN forces). The combination of the two techniques allows us to probe surface wetting properties in far greater details than conventional contact angle measurements, across multiple length (from millimetric to micrometric) and time (from minutes to millisecond droplet dynamics) scales. Advances in surface characterization techniques will greatly improve our understanding of surface wetting and facilitate the future design of novel functional surfaces and materials, including for antifogging and antifouling applications.

Biography: Dan Daniel was born in Indonesia, but spent most of his formative years outside: first in Singapore, followed by undergraduate and postgraduate training in the UK (Cambridge, 2011) and the States (Harvard, 2017), before finally returning to Singapore. He is now a group leader (the Droplet Lab) at the Agency for Science, Research and Technology (A*STAR), Singapore. His main research interests are in the physics of droplets, wetting/adhesion, and soft matter. He has authored and co-authored multiple papers in top journals, including Nature Physics, Nature Materials, PNAS, PRL, and PRX. More recently, he was awarded the IACIS Emerging Investigator Award (2022). He will be moving his lab to KAUST (Saudi Arabia) in Nov 2022.