In situ Studies of Morphology Formation in Solution-Processed Polymer–Fullerene Blends

Barrena, Esther; Buss, Felix; Pérez-Rodríguez, Ana; Sanyal, Monamie; Schmidt‐Hansberg, Benjamin; Klein, Michael F. G.; Scharfer, Philip; Schabel, Wilhelm; Lemmer, Uli

doi:10.1007/978-3-319-28338-8_1

Cited by 1 publication

(1 citation statement)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Common limits for the drying process are the maximum tolerated residual solvent content and the thermal stability of the coating material. The drying conditions can significantly influence the dry film morphology and its resulting functionality. − Simulation models are crucial in order to optimize the conditions of the drying process. Contributing to these models, experiments determine the phase equilibrium of the solvent and polymer and the diffusion kinetics of the solvent in the drying film.…”

Section: Introductionmentioning

confidence: 99%

Drying Kinetics from Micrometer- to Nanometer-Scale Polymer Films: A Study on Solvent Diffusion, Polymer Relaxation, and Substrate Interaction Effects

2021

Self Cite

View full text Add to dashboard Cite

The drying behavior of two different polymers [polyvinyl pyrrolidone (PVP) and polyisobutylene (PIB)] with different glass transition temperatures are investigated and compared as a function of film thickness from micrometer (∼3 μm) to nanometer scale (∼10 nm). The focus of this study is to distinguish between solvent diffusion, polymer relaxation, and substrate confinement of polymer chain mobility toward the interface as the dominating mechanism of drying kinetics. Relaxation kinetics becomes more dominant when the film thickness is reduced, which is shown experimentally for the first time for nanometer-scale film thicknesses. Identical drying curves regardless of the film thickness of PVP/methanol indicate the limitation of solvent transport by relaxation kinetics. The viscoelastic relaxation behavior of the polymer/solvent film is modeled by a Maxwell element. The results are in accordance with the experimental drying curves and allow for the determination of the characteristic relaxation time. Relaxation limitation becomes relevant at high diffusion Deborah numbers when the relaxation timewhich is a function of the deployed material and the polymer/solvent compositionis higher than the characteristic diffusion time in the film. The latter is a function of the polymer/solvent composition and the thickness of the film. Drying curves of PIB/toluene films show additional effect in a substrate-near region of about 5 nm in which polymer chain mobility is confined, resulting in decelerated solvent diffusion. Although this effect near the substrate interface is expected to be present regardless of the film thickness, it becomes more dominant when the substrate-near region represents a significant fraction of the total film thickness. The key to the derived methodology for characterization of the polymer/solvent drying process is to vary dry film thickness from micrometers to a few nanometers which allows us to determine the dominating mechanism of drying kinetics.

show abstract

Section: Introductionmentioning

confidence: 99%