Evaporation of Graphene Droplets: from Fundamentals to the Crystallisation of Organic Molecules

  • Matthew Boyes

Student thesis: Phd


Evaporation of liquids is a fundamental process to both nature and industry; thus, a great deal of research has gone into understanding this phenomenon. It is a key part to many fabrication techniques in technological applications which typically utilise a solvent based method to deposit a material of interest. Studies into the evaporation of droplets tend to be performed with supported droplets (i.e. on a substrate) where the support itself plays a vital role of the dynamics of evaporation. Therefore, a more fundamental understanding of evaporation requires the use of a contactless manipulation method, such as levitation. Evaporation is also widely used in the crystallisation of organic molecules from solution. Controlling crystallisation and subsequently the properties of the resulting product is still a challenge due to a limited understanding of the early stages of crystallisation. The development of new techniques that enable us to gain insights into the nanoscale interactions between molecules is of great scientific interest. The application of templated crystallisation techniques readily allows for the investigation of these different nanoscale interactions and the use of graphene as a template would aid in furthering this area of research. Graphene, the 2D carbon-based allotrope, has garnered a vast amount of scientific interest due to its unique combination of properties, such as exceptionally high electronic conductivity, high mechanical strength, transparency, and impermeability to gases. These properties make graphene an attractive material for a large variety of potential applications. To be effectively applied however, graphene must be produced through a large-scale process. Chemical exfoliation techniques, such as LPE and ECE, are promising routes to achieve this as they can generate large quantities of solution processed graphene with tuneable surface properties. In this thesis, the evaporation process of graphene droplets is focussed upon. Specifically, two main studies are performed: 1) The evaporation of graphene droplets under acoustic levitation was investigated. We observed a distinct change in drying behaviours of graphene droplets when the concentration of graphene was varied, and the solvent system composed of equal parts water and IPA. At a low concentration of graphene, the droplets would reach a critical size and then stop evaporating, becoming stable for many hours in a form similar to a liquid marble. At higher concentrations, the droplets would buckle and produce a graphitic aggregate. In addition to graphene, aqueous glycine droplets were also levitated to allow for homogeneous crystallisation conditions to be studied. It was found that under the influence of acoustic levitation, even with the addition of the anti-solvent IPA, glycine would exclusively form the α-polymorph despite changes in induction times and morphologies that suggested the presence of the less stable polymorph of glycine. 2) Heterogeneous crystallisation of glycine was investigated using graphene-based templates, which were used as either an additive or as the substrate for crystallisation. The preferential crystallisation of α-glycine was induced by graphene-templates, with a pronounced enhancement when additive-templated compared to substrate-templated. Computational modelling experiments highlighted the vital role of the oxygen-containing functional groups on graphene that stabilised the α-form to a greater degree than the β-form. The work revealed that the oxygen content must be carefully optimised to achieve preferential selectivity towards the α-form. These results demonstrate the possibility of using ad hoc designed graphene additives in crystal engineering for polymorph screening studies. Finally, a different approach to produce graphene dispersions, Liquid Phase Exfoliation was utilised to produce stable dispersions in water. Bis-pyrene stabilisers, a new type of stabiliser, were synthesised and investigated for
Date of Award1 Aug 2021
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorCinzia Casiraghi (Supervisor) & Thomas Vetter (Supervisor)


  • Electrochemical Exfoliation
  • Liquid Phase Exfoliation
  • Liquid Marble
  • Glycine
  • 2D Materials
  • Evaporation
  • Crystallisation
  • Graphene
  • Levitation

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