Novel pillar formation in evaporating poly(ethylene oxide) droplets

Doctoral thesis English OPEN
Baldwin, KA (2012)

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.
  • References (110)
    110 references, page 1 of 11

    8.1 Pillar Formation - How Does It Happen? . . . . . . . . . . . . . . 260

    8.1.1 Pinned Drying . . . . . . . . . . . . . . . . . . . . . . . . 260 [4] A. Stannard. Dewetting-mediated pattern formation in nanoparticle assem-

    blies. Journal of Physics: Condensed Matter, 23:083001, 2011. [5] S. M. Rowan, M. I. Newton, F. W. Driewer, and G. McHale. Evaporation

    B, 104(34):8217-8220, 2000. [6] G. Li and K. Graf. Microstructures formation by deposition of toluene

    drops on polystyrene surface. Phys.Chem.Chem.Phys., 11(33):7137-7144,

    2009. [7] L. Pauchard and C. Allain. Buckling instability induced by polymer solution

    drying. Europhysics Letters, 62(6):897-903, JUN 2003. [8] F. Parisse and C. Allain. Drying of colloidal suspension droplets: exper-

    imental study and profile renormalization. Langmuir, 13(14):3598-3602,

    1997. [9] H. Hu and R. G. Larson. Marangoni effect reverses coffee-ring depositions.

    The Journal of Physical Chemistry B, 110(14):7090-7094, 2006. [10] M. Rubinstein and R. H. Colby. Polymer physics, volume 105. Oxford

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