Hole Dynamics in Polymer Langmuir Films
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Transcript of Hole Dynamics in Polymer Langmuir Films
Hole Dynamics Hole Dynamics in Polymer Langmuir Filmsin Polymer Langmuir Films
Lu ZouLu Zou++, James C. Alexander, James C. Alexander**, Andrew , Andrew J. BernoffJ. Bernoff&&, J. Adin Mann, Jr., J. Adin Mann, Jr.##, Elizabet, Elizabeth K. Mannh K. Mann++
++ Department of Physics, Kent State University Department of Physics, Kent State University* Department of Mathematics, Case Western Reserve University* Department of Mathematics, Case Western Reserve University&& Department of Mathematics, Harvey Mudd College Department of Mathematics, Harvey Mudd College## Department of Chemical Engineering, Case Western Reserve Univers Department of Chemical Engineering, Case Western Reserve Universityity
Partially under NSF Grant No. 9984304
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Why hole-closing is Why hole-closing is interesting?interesting?• Phase coexistencePhase coexistence
• Biological systems, e.g. cell membraneBiological systems, e.g. cell membrane
Cell fluid
Protein
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A gas-phase hole in a 2D polymer A gas-phase hole in a 2D polymer liquidliquid
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Fundamental Dynamics Fundamental Dynamics EquationsEquations
• Stokes EquationStokes Equation
• Continuity EquationContinuity Equation
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Assumptions on the surfaceAssumptions on the surface
• 2D liquid phase + very dilute 2D gas2D liquid phase + very dilute 2D gas– Negligible surface viscosityNegligible surface viscosity
• Liquid phase: Liquid phase: – High elasticityHigh elasticity– IncompressibleIncompressible
• Gas phase:Gas phase:– Null compressibilityNull compressibility– Elasticity = 0Elasticity = 0– Circular hole Circular hole
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Assumptions on the subfluidAssumptions on the subfluid
• IncompressibleIncompressible•Bulk viscosity Bulk viscosity
ηη’ ’ •Flow velocityFlow velocity
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Derivation Result – Derivation Result – closing closing raterate
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Vertical Cross section of flVertical Cross section of flow lines in the subfluidow lines in the subfluid
Derivation Result – Derivation Result – Vertical Vertical MotionMotion
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Experimental setupExperimental setup
Brewster Angle MicroscopeBrewster Angle Microscope
Langmuir TroughLangmuir Trough
PDMS = Poly(dimethylsiloxanPDMS = Poly(dimethylsiloxane)e)
MMww=31600=31600 N=427N=427
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0.27mm X 0.27mm X 0.44mm0.44mm
Hole-closing imagesHole-closing images
• Monolayer thickness ~ 0.7 nmMonolayer thickness ~ 0.7 nm• Surface vibrationSurface vibration• Hole Moving aroundHole Moving around
• Surface concentration 0.35 mg/mSurface concentration 0.35 mg/m22
• Monolayer coverage ~ 70%Monolayer coverage ~ 70%• Monolayer Monolayer dark dark • gaseous hole gaseous hole bright bright
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Experimental resultExperimental result
[Ref[Ref]]
[Ref]: E. K. Mann, et al., Phys. Rev. E 51, 5708 [Ref]: E. K. Mann, et al., Phys. Rev. E 51, 5708 (1995)(1995)
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ConclusionConclusion
• Develop a model for the closing of a Develop a model for the closing of a gaseous hole in a liquid domaingaseous hole in a liquid domain within a within a 2D fluid layer, coupled to a fluid bulk 2D fluid layer, coupled to a fluid bulk substratesubstrate
• Experimental result supports the Experimental result supports the prediction on the hole-closing rateprediction on the hole-closing rate
• Suggest an independent means of Suggest an independent means of determining the determining the line tensionline tension
• Predict the Predict the vertical motionvertical motion of the of the underlying incompressible fluidunderlying incompressible fluid
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Future workFuture work
• Improvement on the current experimentImprovement on the current experiment– How to make a better hole?How to make a better hole?– How to obtain better images?How to obtain better images?
• Observation on the vertical motion of thObservation on the vertical motion of the subfluide subfluid
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outlineoutline
• Why interesting (BG and other’s work)Why interesting (BG and other’s work)
• Theory part – model, assumptions, Theory part – model, assumptions, equations and predictionequations and prediction
• Experiment part – setup, difficulties, Experiment part – setup, difficulties, data, result and explanationdata, result and explanation
• Conclusion and future workConclusion and future work
• AcknowledgementAcknowledgement
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AcknowledgementAcknowledgement
• Dr. Elizabeth K. Mann Dr. Elizabeth K. Mann • Dr. James C. AlexanderDr. James C. Alexander• Dr. Andrew J. BernoffDr. Andrew J. Bernoff• Dr. J. Adin Mann, Jr.Dr. J. Adin Mann, Jr.
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