Growth of solid conical structures during multistage drying of sessile poly(ethylene oxide) droplets

Willmer, D, Baldwin, KA ORCID: https://orcid.org/0000-0001-9168-6412, Kwartnik, C and Fairhurst, DJ ORCID: https://orcid.org/0000-0001-5311-0762, 2010. Growth of solid conical structures during multistage drying of sessile poly(ethylene oxide) droplets. Physical Chemistry Chemical Physics, 12 (16), pp. 3998-4004. ISSN 1463-9076

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Abstract

Sessile droplets of aqueous poly(ethylene oxide) solution, with average molecular weight of 100 kDa, are monitored during evaporative drying at ambient conditions over a range of initial concentrations c0. For all droplets with c0 ≥ 3%, central conical structures, which can be hollow and nearly 50% taller than the initial droplet, are formed during a growth stage. Although the formation of superficially similar structures has been explained for glass-forming polymers using a skin-buckling model which predicts the droplet to have constant surface area during the growth stage (L. Pauchard and C. Allain, Europhys. Lett., 2003, 62, 897–903), we demonstrate that this model is not applicable here as the surface area is shown to increase during growth for all c0. We interpret our experimental data using a proposed drying and deposition process comprising the four stages: pinned drying; receding contact line; “bootstrap” growth, during which the liquid droplet is lifted upon freshly-precipitated solid; and late drying. Additional predictions of our model, including a criterion for predicting whether a conical structure will form, compare favourably with observations. We discuss how the specific chemical and physical properties of PEO, in particular its amphiphilic nature, its tendency to form crystalline spherulites rather than an amorphous glass at high concentrations and its anomalous surface tension values for MW = 100 kDa may be critical to the observed drying process.

Item Type:	Journal article
Publication Title:	Physical Chemistry Chemical Physics
Creators:	Willmer, D., Baldwin, K.A., Kwartnik, C. and Fairhurst, D.J.
Publisher:	Royal Society of Chemistry
Date:	2010
Volume:	12
Number:	16
ISSN:	1463-9076
Identifiers:	Number Type 10.1039/b922727j DOI
Divisions:	Schools > School of Science and Technology
Record created by:	EPrints Services
Date Added:	09 Oct 2015 09:48
Last Modified:	25 Feb 2019 09:14
URI:	https://irep.ntu.ac.uk/id/eprint/3052

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