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Morphology, Thickness and Composition Evolution in Supramolecular Block Copolymers Prepared by Dip-Coating Robert E. Prud’homme and C. Géraldine Bazuin Département de chimie Université de Montréal
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Two objectives: 1) to obtain a Ph.D. in polymer science
Stein’s IUPAC lecture in Montréal in 1990 2) to learn English without accent
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1973 picture. On the first row, from right to left, Richard Stein, Do Yoon and Robert Prud’homme.
In the second row, Judy Stein.
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Morphology, Thickness and Composition Evolution in Supramolecular Block Copolymers Prepared by Dip-Coating Robert E. Prud’homme and C. Géraldine Bazuin Département de chimie Université de Montréal Thanks to Sébastien Roland, Alexis Laforgue, David Gaspard, Cé Guinto Gamys and Christian Pellerin
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Two key choices: ► dip-coating method ► adding a small molecule
PS block PVP block Two key choices: ► dip-coating method ► adding a small molecule n m H-bond Naphthol (NOH) Naphthoic acid (NCOOH) DHN
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Block copolymer (BC) self-assembly
In the bulk (melt) Important parameters: fA, fB , and N In thin films (ex. spin-coating + annealing, dip-coating) Additional parameters: surface/interface energetics (air, substrate) – preferential wetting, domain orientation -, and confinement effects solvent evaporation rate, other kinetic effects Supramolecular block copolymers addition of a block selective (H-bonding) small molecule, SM modifies block fractions, interfacial energies, ....
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PS-b-P4VP (71.9K-30.2K) (1:1 = VP:DHN)
Contact angle measurements 86 o mainly PS at surface (thin layer overlaying VP nodules) PS: o P4VP: 62 o 60 o thin P4VP layer overlays entire surface AFM images TEM images 1x1 mm 1x1 m + DHN (dip-coated from THF solution) stained with I2 (P4VP) (washed with MeOH) – DHN pore depth: ~7 nm film thickness: ~7 nm Laforgue, A.; Bazuin, C.G.; Prud’homme, R.E. Macromolecules 2006, 39, 6473.
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PS-b-P4VP (71.9k-30.2k), 5 mg/mL THF solutions (micellar),
SM:VP 1:1, dip-coating rate 2 mm/min, silicon substrates H-bonded to P4VP AFM TEM (I2-stained) 2x2 m intermediate strength 3x3 m strong
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a b c d e a* b* c* e* a’ b’ c’ d’ e’ d* THF solutions Sébastien Roland, R.E. Prud'homme, C.G. Bazuin, ACS Macro Letters 2012, 1, 973. Sébastien Roland, David Gaspard, R.E. Prud'homme, C.G. Bazuin, Macromolecules 2012, 45, 5463.
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Dip-coated PS-P4VP (40.5k-17.5k) films
THF solutions, SM:VP 1:1 Film thickness (nm)
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Sol-gel films new well-known
(Landau+Levich, 1942) Faustini, M.; Louis, B.; Albouy, P.A.; Kuemmel, M.; Grosso, D. J. Phys. Chem. C 2010, 114, 7637 (Figures 1 and 3)
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Sol-gel films PS-P4VP/NOH (1:1) h or ho u
(log-log scale) h or ho u Faustini, M.; Louis, B.; Albouy, P.A.; Kuemmel, M.; Grosso, D. J. Phys. Chem. C 2010, 114, 7637 (Figure 3)
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spheres brush (wetting) layer ǁ , ‗ cyl. ‗ cyl. e’ a’ d’ c’ b’
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sph. ǁ cyl. brush layer lamellar (face-down) e’ a* a’ a’ b* d’ e* c’
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spheres (micellar solutions)
TEM micrographs of cross-sectional slices of I2-stained PS-P4VP/NCOOH 1 mm/min dots (AFM) spheres (micellar solutions) (visible wetting layer) scale bar: 100 nm
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horizontal cylinders (visible wetting layer)
TEM micrographs of cross-sectional slices of I2-stained PS-P4VP/NCOOH 2 mm/min stripes (AFM) horizontal cylinders (visible wetting layer) scale bar: 100 nm
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SM-free PS-P4VP dots (spheres) only
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S. Roland, C. Pellerin, C.G. Bazuin, R.E. Prud’homme,
Macromolecules, 2012, 45, 7964.
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NOH: spheres horizontal cylinders vertical cylinders
b c b* d’ e* c’ c* b’ d* NOH: spheres horizontal cylinders vertical cylinders NCOOH: spheres horizontal cylinders face-down lamellae
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Other Dip-coating Solvents
(10 mg/mL PS-P4VP solution concentration, 1:1 NCOOH:VP) S. Roland, C.G. Gamys, J. Grosrenaud, S. Boissé, C. Pellerin, R.E. Prud’homme, C.G. Bazuin, Macromolecules 2015, 48, 4823.
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film thickness related to D
Vapor pressure (kPa) Viscosity η (mN.s.m-2) Surface tension, γ (mN.m-1) Density, ρ (g.cm-3) D (x 106) p-Dioxane 4.95 1.177 32.75 1.034 0.116 Toluene 3.79 0.560 27.93 0.862 0.087 THF 21.6 0.456 26.5 0.883 0.074 Chloroform 26.2 0.537 26.67 1.479 0.050 draining regime film thickness related to D (at a given dip-coating rate): dioxane > toluene > THF > CHCl3 capillarity regime (dip-coating rate slower than evaporation rate): evaporation rate dominates film thickness
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Conclusions V-shaped dependence of dip-coated film thickness with dip- coating rate (capillarity vs. draining regimes) Films obtained in the capillary regime depend on solvent characteristics (insensitive in the draining regime) Morphologies depend on SM uptake ratio and solution/solvent characteristics (micellar or not, “tightness” of micelles, …)
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Thanks, Prof. Stein, for your mentoring and your friendship
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