Seminar Series

Polymers in a Spin: in situ studies of polymers and colloids during spin coating

Speaker

Associate Professor Jon Howse

Institute

Department of Chemical & Biological Engineering University of Sheffield

Time & Place

Wed, 08 Mar 2017 12:00:00 NZDT in Rutherford Room 531

All are welcome

Abstract

High quality, uniform thin polymer films are routinely produced by the technique of spin coating. Applications for such polymer films beyond photoresist layer fabrication include photovoltaics and light-emitting diodes, where device performance is dependent upon an appropriate phase separated morphology. Developing an understanding of the factors involved in the development of such morphologies is therefore an important goal. The spin coating of polymer blends is a high speed, non-equilibrium process and as such, it is difficult to monitor in situ, with most studies inferring structure development from the resultant final morphology. Over the past 20 years various in situ experimental techniques have been developed, providing insight into the details of the spin coating process itself and opening a route to understanding and controlling morphological development. The majority of studies have been based upon interferometry and light scattering, “based in reciprocal space” and have been able to verify theoretical models of spin coating and the associated phase separation of polymer blends, with direct real-space, in situ studies now a possibility. In this talk I will present an overview of the recent advances we have made in this field and show how recent experimental techniques and advances have allowed for significant progress to be made in our understanding of this process. I shall discuss work which includes recent studies which investigate in-situ studies of crystallization and composition development during phase separation. I will also use this talk to introduce recent in-situ studies of microwave assisted annealing of block-copolymer selfassembly via Small Angle X-ray Scattering experiments where we have installed a custom-made microwave waveguide onto a synchrotron beamline. From this novel experimental set-up we are able to follow the self-assembly process in real-time. Finally, I will introduce a new, low cost, experimental set-up to allow for in-situ laser-scattering of the spin-coating process and will discuss this in relation to the spin-coating of colloidal crystals.

Biography

  • Howse, J. R. et al (2014). On the mechanisms of colloidal self-assembly during spin-coating. Soft Matter. doi:10.1039/C4SM01711K
  • Howse, J. R. et al (2014). Stroboscopic microscopy - Direct imaging of structure development and phase separation during spin-coating. Journal of Polymer Science, Part B: Polymer Physics, 52(1), 17-25. doi:10.1002/polb.23410
  • Howse, J. R. et al (2013). In situ studies of phase separation and crystallization directed by Marangoni instabilities during spin-coating. Advanced Materials, 25(48), 7033-7037. doi:10.1002/adma.201302657
  • Howse, J. R. et al (2011). In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating.. ACS Nano, 5(6), 5124-5131. doi:10.1021/nn201210e