Raman Spectroscopy for the Characterization of Cultural Heritage and Innovative Products Dr. Karine Egly Fraunhofer Institut für Silicatforschung Photos: Fraunhofer ISC
Fraunhofer Institute for Silicate Research ISC Mission Energy Research / Environmental Research / Health Research application-oriented efficient cutting-edge Innovative Materials for Future Products
Contents Timeline Monitoring the synthesis of hybrid polymer materials via the Sol-Gel process Characterization of scratch-resistant hybrid polymer coatings Characterization of high barrier hybrid polymer coatings Investigation of new hybrid coatings with self-healing properties Characterization of electrochromic switching devices Identification of crystalline phases in: Biomimetic applications Gemstones Bronze age artefacts
Time Line Bronze Age ~ 3600 600 BC Raman Effect Discovery Innovative 1928 Devices 2012 Sir Chandrasekhara Venkata Raman
Raman Spectroscopy Data Sheet Excitation of molecular vibrational modes via a monochromatic light source (LASER) Result: Inelastic scattered light = spectrum similar to IR spectrum BUT following specific rules some vibrational modes are strong in Raman and not in IR and vice versa. Non destructive analytical method Almost no preparation: bulk, powder, thin layer, liquid / big or small sample: minimal sample size ideally = 1 µm 3 Rapid methode (below 1 s for spectrum preview) Numerous databanks (free / commercial) available Identification of chemical compounds (organic and inorganic), polymerization reactions, structural changes, material failures
1293 313 Raman Intensity (a.u.) 650 596 504 554 592 430 1483 1092 1050 1453 1410 1275 1601 882 Sol-Gel Process FT-Raman Spectroscopy Hydrolysis of rganoalkoxysilanes e Vinyltriethoxysilane 650 672 1600 1400 1200 1000 800 600 400 Wavenumbers (cm -1 ) 635 640 633 d c b a CH 2 =CH-Si-(-CH 2 -CH 3 ) 3 + H 2 CH 2 =CH-Si-H + H-CH 2 - CH 3 Silanol Ethanol Monitoring of Hydrolysis reaction = Influence on final product
~2 µm 1636 nc=c (DPEPA) 1601 nc=c (vinyl) d (-CH 2 -) Micro-Raman spectroscopy Lens Image plane Variable aperture confocal pinhole Confocal pinhole Beam splitter 1410 d (CH 2 =) Raman Intensity [a.u] Raman Intensity [a.u.] 1456 VTES/TES/DPEPA coating after UV cure Focus plane Microscope objective Coating 1800 1600 1400 1200 1000 800 600 400 200 Wavenumbers [cm -1 ] PMMA Substrate ptical axis z 1800 1600 1400 1200 1000 800 600 400 200 Wavenumbers [cm -1 ]
Raman normalized intensity [a.u.] n (C=) n (C=C) 1456 d (-CH 2 -) 1410 d (CH 2 =) Standard Et Cross-linking of hybrid polymer coatings Et Si Et VTES / TES / DPEPA Air-dried coating UV-cured for 30 s UV-cured for 60 s Et Et Et Si Et Et Si Et Et Vinyltriethoxysilan (VTES) Tetraethoxysilan (TES) 1800 1600 1400 1200 1000 800 600 400 Wavenumbers [cm -1 ] EtCH3 Et Si Et Et H Dipentaerythritolpentaacrylate (DPEPA) Control of curing reactions Determination of conversion (acrylate: 75%; vinylsilane only 35% )
Normalized Raman intensity (a.u.) Micro hardness (MPa) Correlation of Raman spectroscopic data with coating properties Micro-hardness Evidence of dependance between coating s microhardness and organic cross-linking Inorganic network is not solely responsible for the hardness of the coating micro hardness d sci. (-CH 2 -) at 1456 cm -1 d sci. (CH 2 =) at 1410 cm -1 560 540 520 500 480 460 440 10 20 30 40 50 60 UV exposure (s) 420
Raman Intensität [willk. Einheit] Raman-Intensität [willk. Einheit] Epoxid ring conversion in barrier hybrid coatings against water vapor and oxygen permeation Coating on ETFE foil / Thermal curing Correlation with Water Vapor Transmission Rate RM04 auf ETFE (ISC) 3 µm / 130 C luftgetrocknet 2 min 5 min 10 min 60 min 120 min 1600 1400 1200 1000 Wellenzahlen [cm -1 ] 1260 H 2 C CH 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 U159 U160 U161 U162 U163 U164 WVTR >> 0,01 WVTR < 0,01 6m2D52h 3m1D 3m2D52h 6m1D 6m2D4h 3m2D4h Aushärtung Higher cross-linking!
Self-Healing Principle Two layers containing capsules with reactive compounds Layer 1 + catalyst Layer 2 + monomer Micro-Raman-Spectroscopy Reactive compound - reference Reactive compound encapsulated in layer 2 Capsule wall + reactive compound Capsule wall Identification of monomer Evidence of successful encapsulation
Self-Healing Proof of Principle Two layers containing capsules with reactive compounds Layer 1 + catalyst Layer 2 + monomer Micro-Raman-Spectroscopy Reactive compound Layer 2 = Monomer Reactive compound Layer 1= Catalyst Reaction product in scratch after damage = Polymer Identification of reaction product in the scratch Evidence of self-healing More Infos: www.askorr.de
Characterization of electrochromic layers oxidation reduction Colorless (x) Colored (Red) Investigation of vibrational modes during the electrochromic switch - Modified oxidised - Reduced - xidised Study of structural changes occuring through the polymer modification More Infos: www.innoshade.eu
Investigation of structural changes upon artificial weathering 1050 970 1634 1545 1360 951 Raman-Intensität [a. u.] 1659 1150 1113 535 1462 1613 1441 904 949 1297 1003 Influence of the curing parameters on the weathering stability of the resin Phenolformaldehyde Mikro-Raman-Spektroskopie resin, weathered an einem Phenolformaldhehydharz n(c=) keine As prepared Trocknung n(c-) n(c-n) n(c=c) d(-ch Härtungsverfahren Curing 1 1 2 -) Härtungsverfahren Curing 2 2 Härtungsverfahren Curing 3 3 n(cc) Helps to identify the best process 1800 1600 1400 1200 1000 800 600 400 200 Wellenzahlen [cm -1 ]
Poly-L-aspartate [mg/l] Raman Intensity [AU] Biomimetic growth of calcium carbonate in hydrogels The unique properties of inorganic substances formed by living organisms are inspiring for new synthesis routes for high performance materials Growth experiments in polyacrylamide matrices showed that the formation of calcium carbonate is significantly influenced by the gel matrix 9 8 7 Vaterite Aragonite Calcite Vaterite Calcite Aragonite 6 5 4 3 2 1 0 0 0,5 1 1,5 2 1450 1200 950 700 450 200 Distance from the Ca 2+ Source [mm] Wave Number [cm -1 ]
Raman Intensity [a.u.] Carbon story Raman spectroscopy as useful tool for historians and investigators Reconstruction of ancient commercial routes, cultural exchange and know-how 20000 Pottery 1: carbon black (amorphous) Pottery 2: Graphite (hexagonal) Ring: Diamond (cubic) 15000 Pottery 2 10000 5000 0 1800 1600 1400 1200 1000 800 Wavenumbers [cm-1] Ring
Raman Intensität [willk. Einheit] Glass sensor study at the coin collection in Vienna Identification of the deposited layer on highly sensitive glass sensor "Schwamige Kristalle" Fächer Kristallanhäufung Rechtecke Nadelförmige Kristalle 2932 2801 2702 1423 1369 925 760 645 Potassium acetate (fan shaped) Calcium formate 2943 1484 967 4000 3500 3000 2500 2000 1500 1000 500 Wellenzahlen [cm -1 ] Potassium acetate + Calcium acetate
Raman Intensität [willk. Einheit] 1725 1158 1027 617 1592 1451 998 Investigation of old paints on medieval glasses Perfect conservation of the glass with a hybrid polymer layer (RMCER ) over 10 years (Herrgottskirche in Creglingen) Probe 1a (Creglingen) RMCER-G (neu) 1800 1600 1400 1200 1000 800 600 400 200 Wellenzahlen [cm -1 ]
Thank you for your kind attention! Special acknowledgement to: Dr. Uwe Posset, Dr. Johanna Kron, Dr. Uta Helbig, Katrin Wittstadt, Gabriele Maas-Diegeler, Dr. Sabine Amberg-Schwab, Angela Amthor, Dr. Gerhard Schottner, Dr. Jürgen Meinhardt for all the exciting projects and samples! Links to actual projects: www.isc.fraunhofer.de
How to find us Fraunhofer-Institut für Silicatforschung ISC Neunerplatz 2 / 97082 Würzburg / Germany Tel. +49 931 4100-0 E-Mail: info@isc.fraunhofer.de Bronnbach Branch Bronnbach 28 / 97877 Wertheim Phone +49 9342 9221 701 alexandra.forst@isc.fraunhofer.de Fraunhofer Center for High Temperature Materials and Design Gottlieb-Keim-Straße 60 / 95448 Bayreuth Phone +49 921 78 69 31-20 angelika.schwarz@isc.fraunhofer.de Project Group Materials Recycling and Resource Strategies IWKS Brentanostraße 2 / 63755 Alzenau Rodenbacher Chaussee 4 / 63457 Hanau/Wolfgang Phone +49 6023 32039-800 iwks.info@isc.fraunhofer.de Bilder: Fraunhofer ISC