Melis Yetkin

PhD Student
Member of the GRK2516
Group: Prof. Hans-Jürgen Butt & Dr. Michael Kappl, MPI-P
Contact: E-mail, Web

Research Project Area C: Supraparticles – Experiments
Aggregation of Colloids in Evaporating Dispersion Drops

Supraparticles (SPs) are the agglomerates of primary nano- or microscale colloids, during the formation of which, particles interact via weak, physical interactions similar to supramolecular chemistry[1,2]. By assembling NPs into larger entities, SPs reduce the hazards associated with the high mobility and non-specific surface activity of primary NP building blocks[3]. More importantly, SPs offer a wide range of compositional and structural variability, as the design criteria are quite flexible. Properties such as shape, ordering, fractal dimension, density, or porosity can be varied by assembling homo- or heterocomponents through various engineering processes[1]. Such diversity in particle characteristics results in distinct functionalities, and thus, potential applications. Therefore, regulating the structure formation of such suprastructures has attracted considerable attention in many fields, such as colloidal science, soft matter physics, powder technology, and pharmaceutical sciences[4-9].
One facile way to fabricate SPs with complex structures is to evaporate dispersion drops from superamphiphobic surfaces. Using such super liquid-repellent surfaces provides extremely low real contact area and low adhesion, and requires no processing liquids as in the case of microfluidics[2,10-12]. In contrast to spray drying, the evaporation can be performed slowly under well-defined boundary conditions, allowing the structure formation to be studied in detail[2,10-12].
The structure formation is directly related to the interaction forces between the constituents and the kinetics of the assembly process[12-17]. In our research, we investigate the structure of the SPs by tailoring the shape of the primary building blocks and the drying conditions.

SEM images of a) a SP formed by the evaporation-driven assembly of spherical and ellipsoidal particles, the surface of such SP b) at slow drying, and c) at fast drying.

[1] Wintzheimer, S., Granath, T., Oppmann, M., Kister, T., Thai, T., Kraus, T., Vogel, N., Mandel, K. Supraparticles: Functionality from Uniform Structural Motifs. ACS Nano 12(6) (2018) 5093-5120.
[2] Liu, W., Kappl, M., Butt, H.-J. Tuning the Porosity of Supraparticles. ACS Nano 13(12) (2019) 13949–13956.
[3] Mattos, B. D., Greca, L. G., Tardy, B. L., Magalhães, W. L. E., & Rojas, O. J. Green Formation of Robust Supraparticles for Cargo Protection and Hazards Control in Natural Environments. Small 14(29) (2018).
[4] Costa, A. L.; Ballarin, B.; Spegni, A.; Casoli, F.; Gardini, D. Synthesis of Nanostructured Magnetic Photocatalyst by Colloidal Approach and Spray-Drying Technique. J. Colloid Interface Sci. 388 (2012) 31−39.
[5] Wenderoth, S., Granath, T., Prieschl, J., Wintzheimer, S., & Mandel, K. Abrasion Indicators for Smart Surfaces Based on a Luminescence Turn-On Effect in Supraparticles. Adv. Photonics Res. 1 (2020) 2000023.
[6] Zhou, G.-W.; Wang, J.; Gao, P.; Yang, X.; He, Y.-S.; Liao, X.-Z.; Yang, J.; Ma, Z.-F. Facile Spray Drying Route for the Three-Dimensional Graphene-Encapsulated Fe2O3 Nanoparticles for Lithium Ion Battery Anodes. Ind. Eng. Chem. Res. 52 (2013) 1197−1204.
[7] Rial-Hermidaa, M. I., Oliveira, N. M., Concheiro, A., Alvarez-Lorenzo, C., & Mano, J. F. Bioinspired Superamphiphobic Surfaces as a Tool for Polymer- and Solvent-Independent Preparation of Drug-Loaded Spherical Particles. Acta Biomaterialia 10 (2014) 4314–4322.
[8] Broadhead, J.; Edmond Rouan, S. K.; Rhodes, C. T. The Spray Drying of Pharmaceuticals. Drug Dev. Ind. Pharm. 18 (1992) 1169−1206.
[9] Vehring, R. Pharmaceutical Particle Engineering via Spray Drying. Pharm. Res. 25 (2008) 999−1022.
[10] Rastogi, V., Melle, S., Calderón, O. G., García, A. A., Marquez, M., Velev, O. D. Synthesis of Light-Diffracting Assemblies from Microspheres and Nanoparticles in Droplets on a Superhydrophobic Surface. Adv. Mater. 20 (2008) 4263−4268.
[11] Liu, W., Midya, J., Kappl, M., Butt, H.-J., & Nikoubashman, A. Segregation in Drying Binary Colloidal Droplets. ACS Nano 13 (2019) 4972−4979.
[12] Liu, W., Kappl, M., Steffen, W., & Butt, H.-J. Controlling Supraparticle Shape and Structure by Tuning Colloidal Interactions. Journal of Colloid and Interface Science 607 (2022) 1661–1670.
[13] Sekido, T., Wooh, S., Fuchs, R., Kappl, M., Nakamura, Y., Butt, H.-J., & Fujii, S. Controlling the Structure of Supraballs by pH-Responsive Particle Assembly. Langmuir 33(8) (2017) 1995–2002.
[14] Hu, M., Butt, H.-J., Landfester, K., Bannwarth, M. B., Wooh, S., & Thérien-Aubin, H. Shaping the Assembly of Superparamagnetic Nanoparticles. ACS Nano 13(3) (2019) 3015–3022.
[15] Shim, W., Moon, C. S., Kim, H., Kim, H. S., Zhang, H., Kang, S. K., Lee, P. S., & Wooh, S. Tailoring the Morphology of Supraparticles by Primary Colloids with Different Shapes, Sizes and Dispersities. Crystals 11 (2021) 79.
[16] Sen, D., Bahadur, J., Mazumder, S., Verma, G., Hassan, P. A., Bhattacharya, S., Vijaid, K., & Doshi, P. Nanocomposite Silica Surfactant Microcapsules by Evaporation Induced Self Assembly: Tuning the Morphological Buckling by Modifying Viscosity and Surface Charge. Soft Matter 8 (2012) 1955.
[17] Sperling, M., Velev, O. D., Gradzielski, M. Controlling the Shape of Evaporating Droplets by Ionic Strength: Formation of Highly Anisometric Silica Supraparticles. Angew. Chem. Int. Ed. 53 (2014) 586−590.