Paper Number
PO9 

Session
Poster Session

Title
Effect of material rheology on polymer blend thin film morphology

Presentation Date and Time
October 8, 2014 (Wednesday) 6:05

Track / Room
Poster Session / Poster

Authors (Click on name to view author profile)

1. Emerson, Jillian A. (University of Delaware)
2. Furst, Eric M. (University of Delaware, Chemical and Biomolecular Engineering)
3. Epps, III, Thomas H. (University of Delaware)

Author and Affiliation Lines (in printed abstract book)
Jillian A. Emerson, Eric M. Furst, and Thomas H. Epps, III
Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716

Speaker / Presenter 
Emerson, Jillian A.

Text of Abstract
Polymer blends offer a promising and economically viable route to creating materials for a variety of applications including coatings, membranes, and optoelectronics. For these applications, the final material performance is strongly dependent on the morphology of the polymer blends. Thus, knowledge of processing effects on phase separation and the resulting blend morphology is vital to improving the viability of polymer blend materials. In this work, we use the material rheology to predict phase separation in thin films cast by spin coating blends of poly(3-hexylthiophene) [P3HT] with polystyrene [PS]. We compare the experimentally captured drying curves with spin coating models. Meyerhofer extended early flow-based models for spin coating^1,2 to incorporate the effect of evaporation on film thinning.³ This model describes the competition between loss of solution from the substrate (outflow) and loss of solvent (evaporation) for a given angular velocity and initial polymer concentration. The deviation of our data from Meyerhofer’s model is explained in the context of phase separation during spin coating (i.e. the onset of phase separation changes the flow properties). Comparing the onset of phase separation with the polymer/polymer/solvent phase diagram allows us to better understand the relationship between processing conditions and equilibrium phase behavior. Control over phase separation processes during casting and final morphology may be afforded by tuning the viscosity, spin speed, and evaporation rate to promote outflow or evaporation. This work highlights the importance of understanding the material rheology in the context of phase separation during casting to control blend morphologies in thin film geometries.

References
1. Emslie, A. G.; Bonner, F. T.; Peck, L. G. J. of Appl. Phys. 1958, 29, (5), 858.
2. Acrivos, A.; Shah, M. J.; Petersen, E. E. J. of Appl. Phys. 1960, 31, (4), 963.
3. Meyerhofer, D. J. of Appl. Phys. 1978, 49, (7), 3993.