Grant: Evaporative Drying of Droplets and the Formation of Micro-structured and Functional Particles and Film
PI: Professor Colin Bain, Durham University

Presentation: Evaporative Drying of Droplets and the Formation of Micro-structured and Functional Particles and Films - pdf
Professor Andrew Bayly- University of Leeds

The evaporation of sessile droplets can be a useful method to pattern substrates, with inkjet printing technology being particularly good at the selective deposition of functional materials. A predictive understanding of formulations is necessary in order to design systems in which the internal flows generated during drying do not lead to undesirable non-uniform morphologies.  Composition or temperature gradients across the liquid-vapour interface have been shown to induce Marangoni flows which can redistribute suspended material, however studies have mainly taken place on microlitre droplets.


Question/Comment (Mojtaba Ghadiri): The NaCl crystals inside the dried clusters are so perfect.  It would be of interest to recover them for other reaserch  aplications:)

Response (Andrew Bayly): Mojtaba, yes very cubic, might be a challenge getting hold of then they are only 5 - 10 um I think.  But might be able to recreate conditions outside the spray dryer.

Question (Licia Dossi): Hi Andrew, do you have any data on cyclodextrins' droplets?

No response

Question (Jin Sun): @Andrew Bayly, how does the viscoelasticity of HPMC affect the results?

Answer (Andrew Bayly): Jin, There is a little viscoelasticity in the 8% HPMC, which may be having a small effect.  2 and 4% its insignificant

Question (Simon Gibbon): @Andrew am i right to assume that drops in contact with surface don't show the same chaotic behaviour as seen in free floating drops?  My logic being surface no matter how smooth with provide repeatable nucleation of processes in the drop.

Answer (Andrew Bayly): On a surface, for crystallisation, there are a variety of effects, some similar it depends on the conditions. For sodium chloride can get crystals on the surface and then moving down the outside of the droplet.

Question (Mark Brewer): @Andrew Have you considered the effect of different viscosifying chemistry on the droplet behaviour?

Answer (Andrew Bayly): Mark,  chemistry effect on collision behaviour should be limited in simple systems, just down to viscosity and surface tension, and our results agree with the limited other work out there. However, many systems are more complicated, there are some systems that do not have a bouncing regime, milk for example.

Poster: Wetting and drying of aqueous droplets with non-ionic surfactants CnEm - pdf
Jing Shi, Lisong Yang, Colin Bain - University of Durham.

Poster. Single droplet drying kinetics and particle formation fromaerocolloidal suspension microdroplets - pdf
J. Archer*, J. S. Walker, F. K. A. Gregson, D. A. Hardy and J. P. Reid. University of Bristol

Industrial processes such as spray drying of pharmaceutical and food products often involve the drying of aerosol droplets containing colloidal suspensions into powdered microparticles of desired properties. The morphology and surface properties of the final dry products/microparticles obtained after the drying process are strongly influenced by the parameters of the initial aerosol droplet composition and the drying conditions. In particular, the final dry microparticle morphology can be dependent on the dimensionless Péclet number (Pe), which express the relative competition between the diffusion of the dispersed particles within the droplet and the rate of solvent loss via evaporation. In this work, we examine how control over the gas phase drying conditions and initial aerosol droplet composition can be used to influence the aerosol droplet drying kinetics in the gas phase for a range of Péclet numbers. We demonstrate that, for aerosol droplets with initially low feed colloid concentrations and within the constant evaporation regime, the starting composition does not strongly influence the solvent evaporation rate with the initial included nanoparticles (NPs) acting as spectators. However, the gas phase drying conditions, temperature, and relative humidity, directly influence the droplet drying kinetics and the final dry microparticle properties. With a priori knowledge of the droplet drying kinetics from the single droplet measurements, we further demonstrate the possibility of tailoring the morphology of the dried microparticles. Our results extend the fundamental understanding of the mechanisms controlling the drying of aerosol droplets in colloidal suspensions mostly encountered in spray drying applications in the gas phase.


RSC FST Future Formulation IV - The Conference

Grant Page: Predictive formulation of high-solid-content complex dispersions
PIs: Dr Jin Sun, University of Edinburgh & Dr Mark Haw, University of Strathclyde

Grant Page: Virtual Formulation Laboratory for prediction and optimisation of manufacturability of advanced solids based formulations
PI: Dr Csaba Sinka, University of Leicester

Grant Page: Evaporative Drying of Droplets and the Formation of Micro-structured and Functional Particles and Films
PI: Professor Colin Bain, Durham University

Grant Page: Enabling rapid liquid and freeze-dried formulation design for the manufacture and delivery of novel biopharmaceuticals
PIs: Dr Robin Curtis, The University of Manchestr & Professor Paul Dalby, University College London

Grant Page: Complex ORAL health products (CORAL): Characterisation, modelling and manufacturing challenges
PI: Professor Panagiota Angeli, University College London

Grant Page: Formulation for 3D printing: Creating a plug and play platform for a disruptive UK industry
PI: Professor Ricky Wildman, University of Nottingham

Grant Page: INFORM 2020 - Molecules to Manufacture: Processing and Formulation Engineering of Inhalable Nanoaggregates and Microparticles
PI: Professor Darragh Murnane, University of Hertfordshire