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Published on: June 20, 2019
A solution concentration dependent transition from self-stratification to lateral phase separation in spin-cast
A D F Dunbar1, P Mokarian-Tabari, A J Parnell
1Department of Chemical and Process Engineering, University of Sheffield, S1 3JD, Loughborough, UK. a.dunbar@sheffield.ac.uk
The European Physical Journal. E, Soft Matter
|April 22, 2010
Summary
Controlling polymer thin film morphology is possible by adjusting solution concentration during spin casting. Different concentrations yield distinct nano-scale structures, from flat bi-layers to complex phase-separated regions.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Thin films are crucial in various technological applications.
- Controlling nanoscale morphology is key to tuning film properties.
- Phase separation in polymer blends offers a route to complex structures.
Purpose of the Study:
- To investigate the influence of solution concentration on the nanoscale morphology of polystyrene (PS) and deuterated polystyrene-poly(methyl methacrylate) (d-PMMA) blend thin films.
- To establish a method for selective control over thin film morphology through spin casting parameters.
Main Methods:
- Spin casting of PS:d-PMMA blends in toluene at various concentrations.
- In situ characterization using specular reflectivity and off-specular scattering.
- Ex situ analysis via optical microscopy, atomic force microscopy, neutron reflectivity, and ellipsometry.
Main Results:
- Low concentrations produced flat, in-plane phase-separated bi-layers (d-PMMA-rich bottom, PS-rich top).
- Intermediate concentrations resulted in undulating interfaces and secondary phase-separated pockets.
- High concentrations led to laterally phase-separated regions with sharp interfaces and surface secondary phase separation.
Conclusions:
- Solution concentration is a critical parameter for controlling the nanoscale morphology of PS:d-PMMA blend thin films.
- Tailoring concentration allows for predictable formation of different nanostructures, from simple bi-layers to complex phase-separated morphologies.
- The findings provide a pathway for designing functional thin films with desired nanostructures.
