Abstract
An experimental method based on confocal microscopy and particle image velocimetry (PIV) is used to characterize the flow in a polymer solution during solvent casting. The flow inside a 200-μm-thick film of a poly(vinyl alcohol) (PVA) solution is visualized near a vertical wall of a mold using confocal microscopy of seed particles during solvent evaporation at 25, 35, and 45°C, and the corresponding velocity vector fields are determined from projections of the confocal images. Flow toward the vertical wall is observed inside the film as well as a slower Marangoni-type counter flow at the film surface during the initial phase of solvent evaporation, resulting from a polymer concentration gradient along the film due to a local variation in evaporation rate. Total volume of the polymer solution in the observation volume as well as solvent evaporation rate are determined as a function of time, both revealing close correlation to average horizontal velocity data from PIV. The PIV measurements show significant differences in the flow velocity fields at different temperatures. The PIV measurements correlate with the solvent evaporation rates as well as the final polymer thicknesses on the vertical wall of the mold. Surface tension and viscosity measurements are taken for different concentrations of PVA solution.
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References
Adrian RJ (1984) Scattering particle characteristics and their effect on pulsed laser measurements of fluid flow: speckle velocimetry vs. particle image velocimetry. Appl Opt 23:1690–1691
Batchelor GK, Green JT (1972) The determination of the bulk stress in a suspension of spherical particles to order c2. J Fluid Mech 56(3):401–427
Bhattacharya A, Ray P (2004) Studies on surface tension of poly (vinyl alcohol): effect of concentration, temperature, and addition of chaotropic agents. J Appl Polym Sci 93(1):122–130
Choi HJ, Kim SG, Hyun YH, Jhon MS (2001) Preparation and rheological characteristics of solvent-cast poly (ethylene oxide)/montmorillonite nanocomposites. Macromol Rapid Comm 22(5):320–325
Croll SG (1979a) Internal strain in solvent-cast coatings. J Coating Technol 51(648):64–68
Croll SG (1979b) The origin of residual internal stress in solvent-cast thermoplastic coatings. J Appl Polym Sci 23(3):847–858
Deegan RD, Bakajin O, Dupont TF, Huber G, Nagel SR, Witten TA (1997) Capillary flow as the cause of ring stains from dried liquid drops. Nature 389(6653):827–829
Doherty EAS, Meagher RJ, Albarghouthi MN, Barron AE (2003) Microchannel wall coatings for protein separations by capillary and chip electrophoresis. Electrophoresis 24(1):34–54
Girard F, Antoni M, Sefiane K (2008) On the effect of Marangoni flow on evaporation rates of heated water drops. Langmuir 24(17):9207–9210
Hoffmann M, Schlüter M, Räbiger N (2006) Experimental investigation of liquid–liquid mixing in T-shaped micro-mixers using μ-LIF and μ-PIV. Chem Eng Sci 61(9):2968–2976
Hu H, Larson RG (2005) Analysis of the effects of Marangoni stresses on the microflow in an evaporating sessile droplet. Langmuir 21(9):3972–3980
Jung Y, Kajiya T, Yamaue T, Doi M (2009) Film formation kinetics in the drying process of polymer solution enclosed by bank. Jpn J Appl Phys 48(3):031502
Kikuchi K, Mochizuki O (2008) Micro-PIV measurements in micro-tubes and proboscis of mosquito. J Fluid Sci Technol 3(8):975–986
Kinoshita H, Oshima M, Kaneda S, Fujii T (2006) Three-dimensional measurement for internal flow of a micro-droplet using confocal micro-PIV. Nihon Kikai Gakkai Ryutai Kogaku Bumon Koenkai Koen Ronbunshu (CD-ROM) 84
Klank H, Goranovic G, Kutter JP, Gjelstrup H, Michelsen J, Westergaard CH (2002) PIV measurements in a microfluidic 3D-sheathing structure with three-dimensional flow behaviour. J Micromech Microeng 12(6):862–869
Kumacheva E, Li L, Winnik MA, Shinozaki DM, Chengs PC (1997) Direct imaging of surface and bulk structures in solvent cast polymer blend films. Langmuir 13(9):2483–2489
Lima R, Wada S, Tsubota KI, Yamaguchi T (2006) Confocal micro-PIV measurements of three-dimensional profiles of cell suspension flow in a square microchannel. Meas Sci Technol 17(4):797–808
Machell JS, Greener J, Contestable BA (1990) Optical properties of solvent-cast polymer films. Macromolecules 23(1):186–194
Meinhart CD, Wereley ST, Santiago JG (1999) PIV measurements of a microchannel flow. Exp Fluids 27(5):414–419
Mikos AG, Thorsen AJ, Czerwonka LA, Bao Y, Langer R, Winslow DN, Vacanti JP (1994) Preparation and characterization of poly (l-lactic acid) foams. Polymer 35(5):1068–1077
Morgan JR, Yarmush ML (1999) Tissue engineering methods and protocols. Springer, New York
Park JS, Choi CK, Kihm KD (2004) Optically sliced micro-PIV using confocal laser scanning microscopy (CLSM). Exp Fluids 37(1):105–119
Prest WM, Luca DJ (1979) The origin of the optical anisotropy of solvent cast polymeric films. J Appl Phys 50(10):6067–6071
Raczkowska J, Rysz J, Budkowski A, Lekki J, Lekka M, Bernasik A, Kowalski K, Czuba P (2003) Surface patterns in solvent-cast polymer blend films analyzed with an integral-geometry approach. Macromolecules 36(7):2419–2427
Raffel M, Willert C, Kompenhans J (1998) Particle image velocimetry, a practical guide. Springer, Berlin
Santiago JG, Wereley ST, Meinhart CD, Beebe DJ, Adrian RJ (1998) A particle image velocimetry system for microfluidics. Exp Fluids 25(4):316–319
Schreiber HP, Croucher MD (1980) Surface characteristics of solvent-cast polymers. J Appl Polym Sci 25(9):1961–1968
Shinohara K, Sugii Y, Aota A, Hibara A, Tokeshi M, Kitamori T, Okamoto K (2004) High-speed micro-PIV measurements of transient flow in microfluidic devices. Meas Sci Technol 15(10):1965–1970
Siemann U (2005) Solvent cast technology—a versatile tool for thin film production. Prog Coll Pol Sci 130:1–14
Strawhecker KE, Kumar SK, Douglas JF, Karim A (2001) The critical role of solvent evaporation on the roughness of spin-cast polymer films. Macromolecules 34(14):4669–4672
Sultan E, Boudaoud A, Amar MB (2005) Evaporation of a thin film: diffusion of the vapour and Marangoni instabilities. J Fluid Mech 543:183–202
Vozzi G, Flaim CJ, Bianchi F, Ahluwalia A, Bhatia S (2002) Microfabricated PLGA scaffolds: a comparative study for application to tissue engineering. Mat Sci Eng C 20(1):43–47
Wang E, Babbey C, Dunn K (2005) Performance comparison between the high-speed yokogawa spinning disc confocal system and single-point scanning confocal systems. J Microsc 218(2):148–159
Wang GJ, Ho KH, Hsueh CC (2008) Biodegradable polyactic acid microstructures for scaffold applications. Microsyst Technol 14(7):989–993
Willert CE, Gharib M (1991) Digital particle image velocimetry. Exp Fluids 10(4):181–193
Xu X, Luo J (2007) Marangoni flow in an evaporating water droplet. Appl Phys Lett 91(12):124102–124102-3
Yeo LY, Craster RV, Matar OK (2003) Marangoni instability of a thin liquid film resting on a locally heated horizontal wall. Phys Rev E 67(2):056315–056315-14
Zimmermann S, Stoeber B, Liepmann D, Pisano A (2006) Method for forming hollow out-of-plane microneedles and devices formed hereby. US Patent Application 20060025717. Filed April 27, 2005
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The authors acknowledge Thomas Scientific (Swedesboro, NJ, U.S.A.) for supplying the coverslips. Iman Mansoor thanks the British Columbia Innovation Council for funding through the BCIC Innovation Scholarship program.
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Polymer solution flow during solvent evaporation at 25°C; the video is created by piling 2D side projection images of the 3D volumes scanned in 77.2 s intervals (MPEG 786 kb)
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Mansoor, I., Stoeber, B. PIV measurements of flow in drying polymer solutions during solvent casting. Exp Fluids 50, 1409–1420 (2011). https://doi.org/10.1007/s00348-010-1000-3
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DOI: https://doi.org/10.1007/s00348-010-1000-3