Preparation of anisotropic microparticles and their behaviour at liquid interfaces

Forrest, Richard

Abstract

Monolayers of solid particles at the liquid- fluid interface are of considerable interest in both academia and industry. Their behaviour during compression and expansion experiments in a Langmuir trough has important implications on particle stabilisation of foams and emulsions. This has been known for some time with regards to spherical particles. In this investigation, we have studied the role of non- spherical particles at the liquid- fluid interface. Particles have been fabricated using the technique of photolithography. The technique was modified in order to be able to apply it under normal laboratory conditions, thus making it more accessible for the fabrication of non- spherical particles of any size or shape. Flat plate- like particles with well controlled shape and size with disc, oval and rectangular geometry have been fabricated. Monolayers composed of such particles at both the air- water and oil- water interfaces exhibit important differences between each other and spherical particles. The geometry of the monolayers at the interface has been characterised, and preferential ordering of rectangular particles in domains consisting of side to side contacts has been discovered. A strong capillary attraction has been observed between the particles owing to the roughness and shape of the particles. It was found that during compression at the liquid- fluid interface, the surface pressure increases more slowly than that observed for spherical particles and this has been attributed to the tendency of the particles to undergo reorientation, tilting and flipping, the latter always occurred around the long axes of the particles. The thickness of the particles has significant implications on the stability of the monolayer; in addition the tendency for the particles to flip increases as the thickness of the particles is reduced. The non- spherical particles investigated here have been demonstrated to offer great potential as stabilisers of emulsion drops. The technique of photolithography has been utilised for the fabrication of Janus particles consisting of one face coated with metals, polyelectrolytes, silanes and colloidal particles.

Citation

Forrest, R. (2012). Preparation of anisotropic microparticles and their behaviour at liquid interfaces. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4215808

• Thesis Type: Thesis
• Deposit Date: Jul 11, 2014
• Publicly Available Date: Feb 23, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4215808
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: Sep 1, 2012