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Date: 2008/11/7

成大化工演講. Single-Chain and Aggregation Properties in Semiconducting Conjugated Polymer Solutions Rheo-Optical Measurements and Multiscale Simulation. Speaker: C. C. Hua ( 華繼中 ). Complex Fluids & Molecular Rheology Laboratory, Department of Chemical Engineering,

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Date: 2008/11/7

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  1. 成大化工演講 Single-Chain and Aggregation Properties in Semiconducting Conjugated Polymer Solutions Rheo-Optical Measurements and Multiscale Simulation Speaker: C.C. Hua (華繼中) Complex Fluids & Molecular Rheology Laboratory, Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621, Taiwan, R.O.C. Date: 2008/11/7

  2. Real process Spin- coating Cast films Ink-jet printing Conducting conjugated polymerprecursor solution • Introduction & motivation Cambridge Display Technology (CDT) Cambridge Display Technology (CDT) Seiko Epson Corporation PLED display e-Paper Polymer solar cell Flexible PLED display Scientific American Feb. 2004 Seiko Epson Corporation LG.Philips LCD Co. Ltd. Konarka Technologies, Inc.

  3. Viscometric Properties of MEH-PPV Solutions Poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) [Mw: 70,000-10,000 g/mol, PDI: 2.5] A. Effect of aging PS MEH-PPV B. Effect of thermal annealing Hua et al, J Rheol 49, 641 (2005)

  4. Dynamic Light Scattering (DLS)/Photoluminescence (PL): Effects of solvent quality and concentration M/T: 1 mg/ml M/T: 3 mg/ml, no filtration M/C: 3 mg/ml, no filtration M/C M/T Hua et al., Appl. Phys. Lett. 93, 123303 (2008)

  5. Mechanical measuring system Optical measuring system Temperature control system • In situ viscometirc/flow turbidity measuring apparatus

  6. Specific turbidity measuring theory Kerker, M., THE SCATTERIG OF LIGHT AND OTHER ELECTROMAGNETIC RADIATION (Academic Press, San Diego, 1969). van de Hulst, H. C., Light Scattering by Small Particles (Dover Publications, New York, 1981). Derived specific turbidity representation equation

  7. Specific turbidity measuring theory Plot figure of specific turbidity vs. Mie radius Heller, W., and W. J. Pangonis, “Theoretical Investigations on the Light Scattering of Colloidal Spheres. I. The Specific Turbidity,” J. Chem. Phys. 26, 498-506 (1957). Liberatore, M. W., and A. J. McHugh, “Dynamics of shear-induced structure formation in high molecular weight aqueous solutions,” J. Non-Newton. Fluid 132, 45-52 (2005). So, quantity of Mie radius can get from equation of fitting curve.

  8. Experiment design and procedure MEH-PPV/DOP Sample In-situ viscometirc/flow turbidity measurement DLS • Use DLS to measure hydrodynamic radius. • Compared the value with the Mie radius from turbidity measurement. The main idea is to change polymer conc. and aging time to observe their effects on aggregation properties. Shear flow: 10 min Shear rate: 60 [s-1] Flow rested 15 min Altered shear rate Run1 Shear flow: 10 min Shear rate: 151~2,800 [s-1] Run1 is to observe the effect of flow shearing and cessation. Flow rested 15 min Experiment factors setting Shear flow: 10 min Shear rate: 60 [s-1] Flow rested 15 min Altered shear rate Run2 Shear flow: 10 min Shear rate: 151~2,800 [s-1] Run2 is to further study the effect of preshearing. Flow rested 15 min

  9. Page 07 • Specific turbidity signal (w/o aging) 0.02 mg/ml 0.3 mg/ml 1.0 mg/ml 3.0 mg/ml Before shear Before shear Before shear Before shear Before shear Before shear

  10. Specific turbidity signal (2-days aging) 0.3 mg/ml (w/o aging) 0.02 mg/ml 0.3 mg/ml (2-days aging) 0.3 mg/ml 1.0 mg/ml (2-days aging) 1.0 mg/ml 1.0 mg/ml (w/o aging) 3.0 mg/ml Before shear Before shear Before shear Before shear Before shear Before shear

  11. Turbidity measurement vs. viscosity measurement Mie radius Reduced viscosity w/o aging w/o aging • Close correlation was generally noted between these two measurements • The Mie radius and reduced viscosity decreases with increased polymer concentration. • Preshearing effect was quite obvious at lower concentrations

  12. Turbidity measurement vs. DLS measurement • Except for the case with the lowest concentration, good agreement was found between the two measurements for the estimated aggregate size.

  13. Page 15 SALS Multi-angle LS Anton Paar • Ongoing work on rheo-optical measuring systems Dicroism & birefringence Ongoing work by Chen. Flow/turbidity Lenstra, T. A. J., Colloids near phase transition lines under shear, Doctoral thesis, Utrecht University, 2001. Ongoing work by Liu, Wen, and Kuo. SALS & multi-angle LS Wide range of rheo-optical measurement Kume et al., Macromolecules 30, 7232-7236 (1997).

  14. Multi-Angle Dynamic/Static Light Scattering Temperature Controller 10~70oC Sample cell Photomultiplier tube Polarizer 1 Polarizer 2 θ = 30~150o Circulating water Detection arm

  15. Small Angle Light Scattering (SALS) CCD Photodiode 2 θ = 0.5~10o Sample cell Photodiode 1

  16. DAQ Schematic Diagram of SALS Setup Photodiode 1 Photodiode 2 Lens Sample cell Objective lens CCD Laser Beamsplitter Pinhole Iris Iris Spatial filter Mini rod mirror Lens set 1 Lens set 2 2 mm Edmund Onset Ray tracing

  17. Rheo-Turbidity Optical cell Thermal bath Temperature Controller Photodiode 1 Photodiode 2 Optical flow cell Photodiode Rheometer

  18. Flow Birefringence (Crossed Polarizers) Rheometer Polarizer 1 at 45o Photodiode 1 Couette flow cell He-Ne laser Photodiode 2 Polarizer 2 at 135o

  19. Flow Light Scattering (FLS) Lens A Rotor Laser Index matching vat Rotary detection arm (top view) Pinhole A Iris Lens B Pinhole B Detector Data analysis

  20. Optical flow cell for FLS 30 33 66 60 66 60 3 15 33 30 30 5 8 16.5 3 37 37 1.5 3

  21. 主要量測系統: (1) 即時光學—流變系統 I. Particle Interactions II. Microstructures III. Molecular Anisotropy

  22. 主要量測系統: (2)光學旋轉塗佈成膜系統 • I. Ellipsometry (film thickness & reflective index) • II. Aggregation Microstructure/Anisotropy & Hydrodynamics under controlled • Solution Properties (solvent quality, volume fraction, viscosity & volatility) • (b) Spin Rate (c) Baking (d) Interfacial Properties Video Microscopy Laser Doppler, DLS

  23. Non-Equilibrium & Memory Effects Fundamental Particle (Polymer segment) Interactions X-ray Scattering Dynamic Light scattering Molecular Rheology Particle size, shape, Surface modifications, (grafting & charge) Solution properties (solvent quality, concentration, viscosity, volatility) Small Aggregates Static light scattering & Birefringence/ Dichroism Video Microscopy Self-assembly/ Phase separation Interfacial properties (wetting & brushing) Operating Conditions (spin rate,evaporation viscoelasticity) Microscopic/Mesoscopic Structure & Anisotropy Spectroscopy (EL & PL etc), TEM, AFM etc. Optoelectronic/ Mechanical Properties

  24. Parameter-FreeMultiscale Coarse-Grained (CG) Simulations

  25. Y-Z plane Y-Z plane X-Z plane Y-X plane X-Z plane Y-X plane Aggregates versus Entanglements Temperature ＝ 55 ˚C, Pressure ＝1 atm, Time ＝ 1 ns, Time step = 10 fs (c) (a) (b) Hua et al, J Rheol 49, 641 (2005)

  26. Automatic mappings and Langevin Dynamics Simulations: Force-FieldsConstruction for the CG-model Lee, C. K.; Hua, C. C.; Chen, S. A. J. Phys. Chem. B 112, 11479 (2008). Bond length Bond angle Planar angle Intramolecular Toluene vs Toluene Chloroform vs Chloroform Monomer vs Monomer Intermolecular

  27. Parameter-Free, Self-consistent Langevin Dynamics of the CG-Model: from the MD simulation of single-particle diffusivities CGMD : Parallel computation system (IBM-P690 with 4 CPUs) with 36 hrs CGLD :Single-CPU personal with 10 min M / C 6 ns 50MEH-PPV monomers per Kuhn length Which yields the exact (generally poor) solvent qualities for MEH-PPV solutions: Toluene: 0.32 Chloroform: 0.38 M / T 6 ns

  28. Collapsing of ten MEH-PPV chains into an aggregate cluster Nucleation of two small aggregates M / T 0.38 ns M / T 7.5 ns M / T 0.5 ns M/T 0.8 ns M/T 8 ns M/T 0.8 ns M/T 8 ns M / T 0.38 ns M / T 0.38 ns M / C 0.38 ns M/C 0.8 ns M/C 0.8 ns M/C 8 ns M/C 8 ns M / C 7.5 ns M / C 7.5 ns

  29. Brownian Dynamics of Chain Models Basic information of MEH-PPV Chains in solvents at 298K: aEstimated from atomic molecular dynamics simulations. bThe mean-square end-to-end distance. cBased on <R2>end-to-end = K(Nm-1)2, where K is a certain constant independent of the polymer molecular weight. FRC (freely rotating chain) FJC (freely jointed chain) • LKuhn (=17.5 nm): the Kuhn length • h* (= 0.25): hydrodynamic interactions parameter • f: total volume fraction of monomer as polymer chain in a  solvent • Rg,: radius of gyration of a FJC (or FRC) under the -condition • (=LKuhn2/(12kBT)): relaxation time of the Kuhn segment, where , kB and T are the drag coefficient, the Boltzmann constant and absolute temperature The value of  for a given polymer solution can in princinple be determined from the polymer collapsed transition shown above. The values chosen for H and H produce a <R2>end-to-end of FRC/FJC in agreement with the predicted ideal chain behavior.

  30. Aggregation in MEH-PPV Solutions: Freely Jointed Chain Model Case I Case II

  31. Scattering of Single Collapsed Chains/interchain aggregates predicted by Freely Rotating Chain Model (a) (b) SANS profiles of MEH-PPV in (a) chloroform and (b) toluene at 25 °C. Mn = 216,000 g/mol and PDI = 2.0. (Ou-Yang et al., Phys. Rev. E 72, 031802 (2005)) To retrieve pure MEH-PPV contributions from the SANS data, the scattering intensity is normalized as I(q)/()2, where  is the difference of scattering length density between the MEH-PPV monomer and the solvent molecule. Effects of single-chain polydispersity and interchain aggregation qLKuhn > 5, rod-like 1<qLKuhn<5, fractal structure local rod-like feature of MEH-PPV molecules S. C. Shie, C. C. Hua, and S. A. Chen, “Simulation of large-scale material properties of semiflexible chains in poor solvents” to be submitted.

  32. From Freely joined chains to dumbbells Parameter determinations for even more coarse-grained, rigid dumbbell models: The right figure shows that the interchain potential as a function of the separation in the mass centers can be well mimicked by some linear functions Parameter evaluations for the dumbbell: Shie et al. Macroml. Theory. & Simul. 16, 117 (2007)

  33. Mapping and Reverse Mapping tetrahedral defects Mapping Atom model (AMD) Centipede model (CGMD) Reverse Mapping Monomer model (CGLD) Ellipsoid model (CGMC)

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