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Heidkamp, Hannah
Publications (5 of 5) Show all publications
Carlsson, G., Heidkamp, H. & van Stam, J. (2011). Fluorescence microscopy – the most versatile tool for in situ investigation of colloids?. Paper presented at The 25th European Colloid and Interface Society Conference, Berlin, Germany, September, 4-9, 2011..
Open this publication in new window or tab >>Fluorescence microscopy – the most versatile tool for in situ investigation of colloids?
2011 (English)Conference paper, Published paper (Refereed)
Keywords
Fluorescence microscopy, Colloid, Latex
National Category
Natural Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-12316 (URN)
Conference
The 25th European Colloid and Interface Society Conference, Berlin, Germany, September, 4-9, 2011.
Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2014-09-10Bibliographically approved
Heidkamp, H., van Stam, J., Carlsson, G., Moons, E., Dzwilewski, A. & Rogowski, R. (2011). Morphology of P3HT and PCBM blends in thin films obtained with different deposition methods. In: : . Paper presented at 25th European Colloid and Interface Society Conference, Berlin, Germany, September 4-9, 2011.
Open this publication in new window or tab >>Morphology of P3HT and PCBM blends in thin films obtained with different deposition methods
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2011 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Patterns and structures, formed when a semiconducting polymer blend in solution is subject to controlled evaporation, have been of great interest due to their influence on the performance of organic devices. By controlling the processes of pattern formation, function properties of organic semiconductor structures can be tailored, allowing for facile manufacturing of the active layers in organic devices, e.g. solar cells.

By analyzing the morphologies of polymer blends resulting from different deposition methods, a deeper insight into the pattern formation process can be acquired. In this study, we have analyzed the morphology of blends of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) formed upon solvent evaporation. We used the following deposition methods: dip-coating, droplet evaporation within a constrained geometry and drop-casting. Dip-coated films revealed various types of morphology depending on the coating speed. At low coating speeds, where evaporation is the dominant factor, well-ordered patterns were obtained. When increasing the coating speed, viscous forces become dominant over evaporation yielding optically homogenous films [2]. Morphologically similar structures to those observed at low coating speeds, were also obtained with spatially constrained droplets. The blend morphologies were analyzed with polarized, fluorescence and atomic force microscopy [1].

References:

[1] C. M. Björström Svanström, J. Rysz, A. Bernasik, A. Budkowski, F. Zhang, O. Inganäs, M. R. Andersson, K. O. Magnusson, J. J. Benson-Smith, J. Nelson, and E. Moons, Adv. Mat. 21, 4398-4403 (2009)

[2] R. Z. Rogowski and A. A. Darhuber, Langmuir 26, 11485-93 (2010)

National Category
Physical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-14564 (URN)
Conference
25th European Colloid and Interface Society Conference, Berlin, Germany, September 4-9, 2011
Available from: 2012-08-24 Created: 2012-08-24 Last updated: 2019-05-20Bibliographically approved
Heidkamp, H., Rogowski, R., Dzwilewski, A., van Stam, J., Moons, E. & Carlsson, G. (2011). Morphology of polymer blends in films made by dip-coating. Paper presented at Soft and hard materials : A symposium on surface and materials chemistry. Lund, Sweden, October 25-27, 2011.
Open this publication in new window or tab >>Morphology of polymer blends in films made by dip-coating
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2011 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Thin spincoated polymer films are used in various applications and there has been anincreasing demand to understand and get precise control over the film formation process. One of the most exciting applications is organic solar cells which have an active layer made of a polymer based blend. The film morphology has a strong effect on the efficiency of solar cells and therefore it is crucial to understand the film formation process in order to tailor thedesired morphology [1].

In this study we are combining and comparing results from three different deposition processes: drop-casting, sphere-on-flat arrangement and dip-coating. We are using dip-coating to produce thin films of polymer blends with different morphologies under controlled conditions. The main goal is to gain a deeper insight into the processes that occur while solvent evaporates and to understand why certain structures are formed.

Drop-casting allows for little control of the structure formation. In the sphere-on-flat arrangement a droplet of a solution is constrained between a half-sphere and the substrate, which provides more controllable conditions for the deposition process. For more precise control, dip-coating can be used, where a substrate is withdrawn from a solution at a constant speed.

In this study we have used the polymer poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) dissolved in toluene. These components are the model system for studies on organic solar cells [1]. The dip-coated films show a wide variety of morphologies depending on the coating speed. This dependence can be rationalized by the different mechanisms occurring at low and high speeds: At low speeds, evaporation is dominant, [2] resulting in well ordered patterns. At high speeds, viscous forces become dominant, [2] yielding optically homogeneous films.

[1] G. Dennler, M. C. Scharber, C. J. Brabec, Adv. Mat. 21, 1323-1338 (2009)

[2] R. Z. Rogowski and A. A. Darhuber, Langmuir 26, 11485-93 (2010)

National Category
Physical Chemistry
Research subject
Chemistry; Physics
Identifiers
urn:nbn:se:kau:diva-12329 (URN)
Conference
Soft and hard materials : A symposium on surface and materials chemistry. Lund, Sweden, October 25-27, 2011
Available from: 2012-03-16 Created: 2012-03-16 Last updated: 2017-12-06Bibliographically approved
Heidkamp, H., Carlsson, G. & van Stam, J. (2010). Latex particle behavior studied in the wet state with fluorescence microscopy. Paper presented at Molecular Processes at Solid Surfaces 10th Annual Surface and Colloid Symposium, 24-26 November 2010, Lund. Paper presented at Molecular Processes at Solid Surfaces 10th Annual Surface and Colloid Symposium, 24-26 November 2010, Lund.
Open this publication in new window or tab >>Latex particle behavior studied in the wet state with fluorescence microscopy
2010 (English)Conference paper, Published paper (Refereed)
Abstract

Dispersions of latex are often used as model systems due to the well known properties of the latex particles. They can be made with a monodisperse distribution, different extent of cross linking and different surface charges. The behavior of latex particles in the wet state is important for both film formation and understanding what happens in the system when different additives are introduced. Latex is used in many different blends and one common additive is surfactants, both for stabilization during manufacturing and for adjusting the system features in different applications. A suitable method for studying latex dispersions in wet state is fluorescence microscopy. By adding latex particles with similar size and charge, marked with a fluorophore, particle movements can be followed even if the particle radius is below microscope resolution limit. This can be used for studying particle behavior in dispersions with different additives, in order to see how the additives affect the latex particles.



By measuring the latex particles displacement, diffusion coefficients can be determined. This has been successfully used for both high and low latex volume fractions [1-3]. Since surfactants are a common additive, the focus in our studies lies on interactions between surfactants and negatively charged latex. When DoTAB (dodecyl trimethyl ammonium bromide), a cationic surfactant, is added to the latex dispersion, an interesting behavior can be seen. Both diffusion coefficients and conductivity measurements show that at a certain concentration, when DoTAB has neutralized the latex particles, aggregates are formed. When the DoTAB concentration is raised even more, the aggregates dissolve. Light scattering measurements give the same indications.



Combined with other studies, such as film formation, the particle behavior gives important information about what happens in the system when different concentration of both latex and additives are used.



[1] Carlsson G., Warszynski P. and van Stam J., J. Colloid Interface Sci., 2003, 267, 500-508 [2] Carlsson G., Järnström L. and van Stam J., J. Colloid Interface Sci., 2006, 298, 162-171

[3] Carlsson G. and van Stam J., Nord. Pulp Pap. Res. J., 2005, 20, 192-199

Keywords
fluorescence microscopy, diffusion, latex
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-10516 (URN)
Conference
Molecular Processes at Solid Surfaces 10th Annual Surface and Colloid Symposium, 24-26 November 2010, Lund
Available from: 2012-02-08 Created: 2012-02-08 Last updated: 2014-09-10Bibliographically approved
Heidkamp, H., Carlsson, G., Moons, E. & van Stam, J. (2010). Polymer film formation studied with fluorescence microscopy and AFM. In: Molecular Processes at Solid Surfaces: 10th Annual Surface and Colloid Symposium. Paper presented at Molecular Processes at Solid Surfaces 10th Annual Surface and Colloid Symposium, 24-26 November 2010, Lund (pp. 49).
Open this publication in new window or tab >>Polymer film formation studied with fluorescence microscopy and AFM
2010 (English)In: Molecular Processes at Solid Surfaces: 10th Annual Surface and Colloid Symposium, 2010, p. 49-Conference paper, Oral presentation only (Refereed)
Abstract [en]

Thin polymer films are used in many applications such as paint, paper coatings and electronic devices. For these applications, it is important to have knowledge about the film formation process, since it affect the film morphology and the morphology is important for the applications.One method for studying film formation in situ is fluorescence microscopy. By labeling a target molecule or particle with a fluorophore, the targets movements can be traced as the solvent evaporates [1-3]. If information gained from studies of particle movements during film formation and wet state behavior are combined, information about the film formation process can be obtained. Examination of the final film surfaces with regular light microscopy and AFM gives additional information about the film formation.These methods have been used for studying the formation of negatively charged latex films. It was shown that the films are greatly affected by adding positively charged surfactants [4-5]. Since latex is a water-based system it has relatively long drying times. Systems based on high-vapor pressure organic solvents have much shorter drying times and the film formation occurs under non-equilibrium conditions. This results in incomplete phase separation, which in turn gives microstructures in the film. These microstructures are of great interest since they affect the properties of the film and its function [6-7]. Our aim is to develop the methods used for latex studies in order to be able to apply them to study film formation of polymer blends used for photovoltaic applications. The goal is to get more knowledge about the film forming process and a deeper understanding about the mechanisms behind the formation of microstructures.[1] Carlsson G., Warszynski P., van Stam J., J. Colloid Interface Sci., 2003, 267, 500-508[2] Carlsson G., van Stam J., Nord. Pulp Pap. Res. J., 2005, 20, 192-199[3] Carlsson G., Järnström L., van Stam J., J. Colloid Interface Sci., 2006, 298, 162-171[4] Heidkamp H., Master thesis, Karlstad University 2009.[5] Paakkonen, J., Master thesis, Karlstad University 2010.[6] Björström C.M., Magnusson K.O., Moons E., Synth. Metals, 2005, 152, 109-112[7] Moons E., J. Phys.: Condens. Matter, 2002, 14, 12235-12260

Keywords
fluorescence microscopy, film formation, atomic force microscopy
National Category
Chemical Sciences Physical Sciences
Research subject
Chemistry; Physics
Identifiers
urn:nbn:se:kau:diva-10515 (URN)
Conference
Molecular Processes at Solid Surfaces 10th Annual Surface and Colloid Symposium, 24-26 November 2010, Lund
Available from: 2012-02-08 Created: 2012-02-08 Last updated: 2017-12-06Bibliographically approved
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