Nearly-zero contact angle hysteresis on lubricated surfaces

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Schellenberger et al, Soft Matter, 2015. Static droplet: contact angle ... Static droplet: nm lubricant film γsl > γso + γlo and repulsive A > 0 thin film interference s o.
Nearly-zero contact angle hysteresis on lubricated surfaces Dan Daniel, IMRE, A*STAR

2011

1 mm

Oleoplaning droplets on lubricated surfaces

lubricant film lubricant film

2011

Lubricated

repels blood …

and crude oil

2005

“Slippery composite surface” that is “hemi-solid, hemi-liquid” with “non-measurable” contact angle-hysteresis.

2005

“Slippery composite surface” that is “hemi-solid, hemi-liquid” with “non-measurable” contact angle-hysteresis. Lubricated surfaces, a rose by any other name … SLIPS, LIS, Slippery pre-suffused surfaces, LubiSS

Outline Static: droplet shape and geometry Dynamic: oleoplaning droplet with nearly-zero hysteresis Comparison with lotus-effect surface Thoughts/Open questions

Static droplet: contact angle

θapp θapp ~ 100ο for water

Static droplet: contact angle no cloaking

with cloaking

γl < γlο + γο

γl > γlο + γο

θapp θapp ~ 100ο for water

Static droplet: contact angle no cloaking

with cloaking

γl < γlο + γο

γl > γlο + γο

θapp θapp ~ 100ο for water

Modified Young’s Equation cos θapp = (γο – γlο)/ γeff γeff = γl or γlο + γo no/with cloaking

Static droplet: contact angle no cloaking

with cloaking

γl < γlο + γο

γl > γlο + γο

θapp θapp ~ 100ο for water

Modified Young’s Equation cos θapp = (γο – γlο)/ γeff γeff = γl or γlο + γo no/with cloaking Independent of micro-/nano-structures

Static droplet: contact angle

Data from Wong et al, Nature, 2011 Schellenberger et al, Soft Matter, 2015

Static droplet: contact angle

no cloaking Data from Wong et al, Nature, 2011 Schellenberger et al, Soft Matter, 2015

with cloaking

Static droplet: nm lubricant film γsl > γso + γlo and repulsive A > 0

l

o s

thin film interference

Static droplet: nm lubricant film γsl > γso + γlo and repulsive A > 0

rext

rint

thin film interference

low pressure in ridge

|ΔP| ≈ γo/rext ≈ γlo /rint

Static droplet: nm lubricant film γsl > γso + γlo and repulsive A > 0

25 nm rext

rint

thin film interference

low pressure in ridge

|ΔP| ≈ γo/rext ≈ γlo /rint

balanced by h ~ (r A/ γ)1/3 tens of nm

Π ≈ A/6πh3

Disjoining pressure

Static droplet: nm lubricant film on top of posts

speed 4x nm film

40 um

film thickness set by post heights

no contact line pinning

Comparison with lotus-effect surfaces

speed 4x

50 um

air film instead of lubricant film

with contact line pinning

Droplet oleoplanes with Landau-Levich film static

dynamic

U rint hLLD ~ nm film

~ um film hLLD ~ rint (ηU/γlo)2/3 = rint Ca2/3

rext

Droplet oleoplanes with Landau-Levich film static

dynamic

U rint hLLD ~ nm film

~ um film hLLD ~ rint (ηU/γlo)2/3 = rint Ca2/3 = (γlo / γo) rext Ca2/3

rext

Droplet oleoplanes with Landau-Levich film static

dynamic

U rint hLLD h = hp

h > hp hLLD ~ rint (ηU/γlo)2/3 = rint Ca2/3 = (γlo / γo) rext Ca2/3

rext

Droplet oleoplanes with Landau-Levich film

stationary hfilm = hp

moving hfilm = hLLD

0.1 mm

stop motion hfilm à hp

Droplet oleoplanes with Landau-Levich film dynamic

U

F ~ ηoU/hLLD (2a l ) = 2aγlo Ca2/3

rint hLLD

Viscous dissipation in transition region l ~ rint Ca1/3

l

Droplet oleoplanes with Landau-Levich film dynamic

U

F ~ ηoU/hLLD (2a l ) = 2aγlo Ca2/3

rint hLLD

Viscous dissipation in transition region l ~ rint Ca1/3

l Viscous dissipation in wetting ridge (Tanner’s law) θw ~ Ca1/3 θw

F ~ (ηoU / θw) 2a = 2aγ Ca2/3 o Keiser et al, Soft Matter, 2017

Custom-built force sensor to measure dissipation force F = k Δx 2 μl droplet, U = 0.3 mm/s

U

Δx

Contact angle hystersis Δcos θ ~ Ca2/3

F/2aγ

F ~ ηoU/hLLD (2a l ) = 2aγlo Ca2/3

Ca

Contact angle hystersis Δcos θ ~ Ca2/3

F/2aγ

F ~ ηoU/hLLD (2a l ) = 2aγlo Ca2/3 Δcos θ = F/ 2aγl = (γlo / γl) F/ 2aγlo ~ Ca2/3 Ca

Contact angle hystersis Δcos θ ~ Ca2/3

F/2aγ

F ~ ηoU/hLLD (2a l ) = 2aγlo Ca2/3 Δcos θ = F/ 2aγl = (γlo / γl) F/ 2aγlo ~ Ca2/3 Ca Δcos θ à 0, Ca à 0 Nearly zero hysteresis No contact line pinning

Custom-built force sensor currently at IMRE, A*STAR

light camera

Interference Microscopy vibration-free

Comparison with lotus-effect surfaces

Contact line pinning on lotus-effect surface

100 um

Contact line pinning on lotus-effect surface

Micro-droplets after breakup of capillary bridges

F independent of U for lotus-effect surfaces

F independent of U for lotus-effect surfaces

Δcos θ > 0, Ca à 0 finite hysteresis

Results presented can be found in D. Daniel, J.V.I Timonen, R. Li, S.J. Velling and J. Aizenberg “Oleoplaning droplets on lubricated surfaces” Nat. Phys. 2017 D. Daniel+, J.V.I Timonen, R. Li, S.J. Velling, M.J. Kreder, A. Tetreault and J. Aizenberg+ “Origins of extreme liquid repellency on structured, flat, and lubricated surfaces” in revision to Phys. Rev. Lett. (and ArXiv) +co-corresponding authors M.J. Kreder*, D. Daniel*, A. Tetreault , Z. Cao, B. Lemaire, J.V.I Timonen and J. Aizenberg “Film dynamics and lubricant depletion by droplets moving on lubricated surfaces” in revision to Phys. Rev. X *co-first authors

Useful literature A. Keiser, L. Keiser, C. Clanet and D. Quere “Drop friction on liquid infused surfaces” Soft Matter 2017 M. Tress, S. Karpitschka, P. Papadopoulos, J. H. Snoeijer, D. Vollmer and H.-J. Butt “Shape of a sessile drop on a flat surface covered with a liquid film” Soft Matter 2017 F. Schellenberger et al “Direct observation of drops on slippery lubricant-infused surfaces ” Soft Matter 2015 J. D. Smith et al “Droplet mobility on lubricant-impregnated surfaces ” Soft Matter 2013 A. Lafuma and D. Quere “Slippery pre-suffused surfaces.” Euro. Phys. Lett. 2011

Thoughts and open questions

Contact angle hysteresis for high Ca

our work

Keiser et al, 2017

Keiser et al, Soft Matter, 2017

Contact angle hysteresis for different initial film thicknesses Dissipa0ve force for different lubricant heights

3.0

0.5 μm

Fd (μN)

2.5

3 μm

2.0 1.5 1.0 h = 0.5 um h = 3 um h = 6 um

0.5 0.0 0.0

0.2

0.4 0.6 U (mm/s)

0.8

1.0

Δcos θ ~ Ca2/3 independent of initial h for thick micron-film

6 μm

Contact angle hysteresis for different initial film thicknesses Dissipa0ve force for different lubricant heights

3.0

0.5 μm

Fd (μN)

2.5

3 μm

2.0 1.5 1.0 h = 0.5 um h = 3 um h = 6 um

0.5 0.0 0.0

0.2

0.4 0.6 U (mm/s)

0.8

1.0

Δcos θ ~ Ca2/3 independent of initial h for thin nano-film ?

6 μm

Contact angle hysteresis for structured surfaces with thin nano-film ?

Dai et al, ACS Nano, 2015 Slippery Wenzel State

Thanks to …

Prof. J. Aizenberg

M. J. Aizenberg

R. Li

S. J. Velling

Prof. J. V. I. Timonen

A. Tetreault

Prof. Bob. E Cohen

Prof. Paul V. Braun

I can be contacted at [email protected] http://dandaniel.me/