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Functional Polymer Blends: A General Approach for the Design of Optical Materials with Tailored Properties

Functional Polymer Blends: A General Approach for the Design of Optical Materials with Tailored Properties. Christoph Weder Department of Macromolecular Science and Engineering. Functional Polymer Blends. Summary. Approach:

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Functional Polymer Blends: A General Approach for the Design of Optical Materials with Tailored Properties

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  1. Functional Polymer Blends: A General Approach for the Design of Optical Materials with Tailored Properties Christoph Weder Department of Macromolecular Science and Engineering

  2. Functional Polymer Blends Summary Approach: Blending of "passive" polymers with minor fractions of "active" guest molecules, which introduce selected functionalities. Motivation: Rather than developing new materials systems ‘from scratch’, the approach attempts to combine the property matrices and processing protocols of well-known polymers with the exceptional, readily tailored properties of functional organic molecules. Challenges: Characterize and control supramolecular architectures.

  3. Functional Polymer Blends Outline Light-Polarizing Photoluminescent Systems Excimer Probes Functional Multilayer Films Conclusions

  4. Linear Polarization of Light Introduction Linearly polarized light is usually generated by the use of dichroic polarizers Applications: Liquid crystal displays, sunglasses, optical filters Dichroic Polarizer: Uniaxially oriented absorbing dyes, linearly polarized absorption, efficiency < 45 % Photoluminescent (PL) Polarizer: Uniaxially oriented luminescent molecules, linearly polarized emission, Combination of polarizer and ‘active’ color filter

  5. Light-Polarizing PL Polymers PL LCDs Science 1998, 279, 835. PCT IB98/00998 (1998)

  6. Light-Polarizing PL Polymers PL LCDs Science 1998, 279, 835. WO 9901792 (1999)

  7. Light-Polarizing PL Polymers Security Features WO 0019016 (2001)

  8. Light-Polarizing PL Polymers Processing Adv. Mater.1997, 9, 1035.J. Mater. Chem. 1999, 9, 2221.

  9. Light-Polarizing PL Polymers Properties

  10. Light-Polarizing PL Polymers Properties Polarized absorption and emission of oriented ( = 80) 2 % w/w EHO-OPPE / UHMW PE blend films DRA = 57 DRE = 72

  11. Light-Polarizing PL Polymers Orientation Mechanism Synth. Met.2001, 124, 113.

  12. Light-Polarizing PL Polymers Orientation Mechanism

  13. Light-Polarizing PL Polymers Orientation Mechanism J. Phys. Chem.2000, 104, 5221.

  14. Light-Polarizing PL Polymers Patterning Polarizer unpolarized 0° 90°

  15. Nature1998, 392, 261.Macromolecules 1999, 32, 4677. Phys. Chem. Chem. Phys. 1999, 1, 5697.

  16. Cyano-OPVs Excimer Formation upon p-p stacking 1,4-bis(a-cyano-4-methoxystyryl)-2,5-dimethoxybenzene BCMDB: 644 506/538 Synthesis 2002, 1185. US Patent Appl. filed.

  17. Cyano-OPVs Excimer Formation upon p-p stacking 1,4-bis(a-cyano-4-methoxystyryl)-benzene BCMB: 561 459/485

  18. Cyano-OPVs Excimer Formation upon p-p stacking Birks, J. Photophysics of Aromatic Molecules, Wiley, New York 1970.

  19. Cyano-OPVs Synthesis R1R2Yield BCMDB: MeO MeO 89% BCMB: MeO H 90% BCEHODB: 2-Ethylhexyloxy MeO 83% Synthesis 2002, 1185. US Patent Appl. filed.

  20. Excimers as Molecular Probes Diffusion Dyeing Polymer filmDyeSolvent (toluene, CHCl3) Diffusion dyeing Rinsing, drying

  21. Excimers as Molecular Probes Diffusion-Dyed Polymer Blends PL spectra of LLDPE / BCMDB blend film (~0.1 % w/w) - Influence of tensile deformation: PL spectra of LLDPE / BCMDB blend films: [dye] (% w/w): (—) ~0.02, (—) ~0.06, (—) ~0.1, (—) ~0.3 Adv. Mater. 2002, 22, 1625-1629.; US Patent Appl. Filed.

  22. Excimers as Molecular Probes Diffusion-Dyed Polymer Blends PL lifetime of LLDPE / BCMDB blend films (ex 481 nm): [dye] / % w/w: ●~0.02, ●~0.1,■ ~0.1 stretched to 200 % 530 nm 650 nm

  23. Excimers as Molecular Probes Melt Processing of Blends PolymerDye Extrusion Polymers: LLDPE, PP; Film thickness ~100mm; Dye concentration 0.01 – 0.40 % w/w

  24. Melt-Processed BCMBD/LLDPE Blends Properties PL spectra of freshly quenched LLDPE / BCMDB blend films: [dye] / % w/w: (—) 0.01, (—) ~0.05, (—) ~0.1, (—) ~0.20, (—) ~0.40

  25. Melt-Processed BCMBD/LLDPE Blends Properties PL spectra of LLDPE / BCMDB blend film (~0.18 % w/w) Influence of conditioning at room temperature: Polym. Mater. Sci. Eng.2003, In Press.

  26. Melt-Processed Blends Phase Behavior

  27. Melt-Processed BCMBD/LLDPE Blends Conditioning PL spectra of a LLDPE / BCMDB blend film (~0.18 % w/w) before / after conditioning at room temperature: PL spectra of a LLDPE / BCMDB blend film (~0.18 % w/w) before / after conditioning at room temperature:

  28. Melt-Processed Blends Mechanical Deformation PL spectra of a conditioned LLDPE / BCMDB blend film (~0.18 % w/w) before / after deformation to l = (l-l0)/l0 = 300 % PL spectra of a conditioned LLDPE / BCMB blend film (~0.18 % w/w) before / after deformation to l = (l-l0)/l0 = 300 %

  29. Excimers as Molecular Probes Application • Anti -Tampering Films • Security Features / Brand Protection • Integrated Failure Indicators • - Protective Gear • - Load-bearing Structures • - Adhesives • . • . • .

  30. AB Feedblock Extruder A Extruder B Melt Pump B Melt Pump A Multipliers Exit Die Cross- Section of LayerMultiplier Flow Direction Layer Multiplier Functional Multilayer Films Process of Multilayering E. Baer et al. Processing and Properties of Polymer Microlayered Systemsin Polymer Process Engineering 97; Coates, P.D. Ed.; The Institute of Materials, London:1997, 137-157.

  31. n1 n2 n1 n2 Functional Multilayer Films Reflective Films Films with alternating layers of two polymers of different refractive indices are highly reflective.

  32. n1 n1 n2 n2/n3/n2 n1 n1 n2 n2/n3/n2 n1 n1 Functional Multilayer Films Photoreactive Films A B C • Incorporation of photoreactive elements in reflective multilayer films • Multilayer films with alternating ‘inert’ and ‘photoreactive’ layers • Exposure of films changes RI of alternate photoreactive layers • By selectively exposing certain areas of a film to UV radiation, patterns can be produced due to the RI change in alternate layers • Low-cost, tuneable optical elements (dielectric mirrors, security features,…)

  33. Functional Multilayer Films Photoreactive Films Polymers used for photoreactive multilayer films Photodimerization reaction of cinnamic acid • Cinnamic acid dimerizes in a 2+2 cycloaddition reaction to form truxillic acid upon exposure to high-energy UV light (λ = 278 nm) • Upon dimerization the refractive index is reduced from 1.555 to 1.523

  34. Effect of composition on Tg Phase Behavior of PMMA-CA Blends • Tg of blends decreases with concentration of CA  CA has a plasticizing effect on PMMA • Homogeneous mixtures of PMMA-CA are obtained up to a concentration of 20% CA w/w

  35. Photoreaction Photophysical Behavior of PMMA-CA Blends Change of the UV absorption spectrum of a PMMA-CA blend upon exposure to a 100 W air-cooled Hg lamp (higher intensity)

  36. Refractive Index Photophysical Behavior of PMMA-CA Blends RI of blends increases linearly with composition RI of blends decreases upon exposure to UV; The relative RI change increases with the concentration of CA

  37. PMMA/PMMA-CA Photopatterning of Multilayer Films PMMA/PMMA multilayer film PMMA-CA monolithic film 100 µm PMMA/PMMA-CA (15 % w/w) 1024 layers, d = 50 nm US Prov. Appl. filed

  38. PC/PMMA-BZPO Photopatterning of Multilayer Films PC/PMMA-BZPO (0.1 % w/w) 1024 layers, d = 75 nm J.Mater. Chem.2002, 12, 2620-2626 .

  39. New Concepts Functional Multilayer Films < 5 nm Orientation Integration of PL dyes in reflecting cavity: Optically stimulated lasing? “Forced assembly” of PL dyes: Spatially resolved (polarizing) energy transfer “Forced assembly” of p- and n- type polymer semiconductors: Efficient charge separation?

  40. Conclusions Functional Polymer Blends The blending of “passive” matrix polymers with minor amounts of “active” guest molecules represents an attractive, general concept for the design of functional polymer systems. Adequate characterization and control of supramolecular architectures – at various levels – is important.

  41. Acknowledgements CWRU Weder Group CWRU Macro Science Brent Crenshaw Ximei Sun Dr. Eric Baer Akshay Kokil Ravisubash Tangirala Dr. Anne Hiltner Christian Huber Eric Hittinger Dr. Christiane Löwe Dr. Christoph Kocher CWRU Physics Dr. Michael Schroers Dr. Quinghui Chu Dr. Kenneth Singer ETHZ Materials ETHZ Chemistry Dr. Cees Bastiaansen Dr. Bert Hecht Dr. Walter Caseri Dr. Alois Renn Dr. Christoph Kocher Dr. Werner Trabesinger Dr. Andrea Montali Prof. Urs Wild Dr. Anja Palmans Dr. Paul Smith Dr. Theo Tervoort Funding 3M Nontenured Faculty Award National Science Foundation DMR-0215342 DuPont Aid to Education Grant Sumitomo Bakelite Co. DuPont Young Professor Grant The Goodyear Tire and Rubber Company Hayes Foundation Equipment Grant The Petroleum Research Foundation Landqart Co.

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