Novel pillar formation in evaporating poly(ethylene oxide) droplets

BALDWIN, K.A., 2012. Novel pillar formation in evaporating poly(ethylene oxide) droplets. PhD, Nottingham Trent University.

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Abstract

Unlike the familiar “ring-stain" formed when spilt coffee drops are left to dry, liquids containing high molecular weight polymer molecules leave a range of other deposit pat terns. In this thesis I observe that aqueous solutions of the polymer poly(ethylene oxide) (PEO) dries to form either the common coffee-ring stain, flat uniform “pancakes", or tall central “pillars". To investigate this phenomenon, I varied experimental factors including: atmospheric temperature, humidity and pressure; polymer molecular weight and concentration; water-ethanol solvent ratios; droplet volume, contact angle and inclination. These factors indicate a region in parameter-space in which central pillars form, favouring fast drying, low temperature, high contact angle, high concentration, high or low (but not intermediate) water-ethanol ratio, and intermediate molecular weight. I identify four stages in the pillar forming drying process, including a pseudo-dewetting liquid stage which appears to be driven by the formation of a contracting spherulite collar around the droplet's 3-phase contact line.

Item Type: Thesis
Creators: Baldwin, K.A.
Date: 2012
Rights: This work is the intellectual property of the author K. A. Baldwin. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the owner of the Intellectual Property Rights.
Divisions: Schools > School of Science and Technology
Depositing User: EPrints Services
Date Added: 09 Oct 2015 09:36
Last Modified: 09 Oct 2015 09:36
URI: http://irep.ntu.ac.uk/id/eprint/347

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