Structure evolution of spin-coated phase separated EC/HPC films
Licentiate thesis, 2021
The influence of spin-coating parameters and EC:HPC ratio on the final phase-separated structure and the film thickness was determined. Varying spin speed and EC:HPC ratio gave us precise control over the characteristic length scale and thickness of the film. The results show that the phase separation occurs through spinodal decomposition and that the characteristic length scale increases with decreasing spin speed and with increasing HPC ratio. The thickness of the spin-coated film decreases with increasing spin speed.
Furthermore, optimized spin-coating parameters were selected to study the kinetics of phase separation in situ, in particular the coarsening mechanisms and the time dependence of the domain’s growth as a function of EC:HPC ratio. We identified two main coarsening mechanisms: interfacial tension driven hydrodynamic growth for the bicontinuous structure and diffusion driven coalescence for the discontinuous structures. In addition, we obtained information on the wetting, the shrinkage, and the evaporation process by looking at a film cross section, which allowed an estimation of the binodal of the phase diagram.
The findings from this work give a good understanding of the mechanisms responsible for the morphology development and open the road towards tailoring thin EC/HPC film structures for controlled drug release.
controlled drug release
confocal laser scanning microscope
phase separation mechanisms
Chalmers, Physics, Nano and Biophysics
Structure evolution during phase separation in spin-coated ethylcellulose/ hydroxypropylcellulose films
RSC Soft Matter,; Vol. 17(2021)p. 3913-3922
Carmona, P., Röding, M., Särkkä, A., Olsson, E., von Corswant, C., & Lorén, N. - Structure formation and coarsening kinetics of phase-separated spin-coated ethylcellulose/hydroxypropylcellulose films.
PJ-salen Fysik Origo Kemigården 1 - contact email@example.com for the password to the Zoom online defence
Opponent: Associate Professor Leonard Sagis, Department of Agrotechnology and Food Sciences, Wageningen University, the Netherlands