Raman Spectroscopy for the Characterization of Cultural Heritage and Innovative Products

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1 Raman Spectroscopy for the Characterization of Cultural Heritage and Innovative Products Dr. Karine Egly Fraunhofer Institut für Silicatforschung Photos: Fraunhofer ISC

2 Fraunhofer Institute for Silicate Research ISC Mission Energy Research / Environmental Research / Health Research application-oriented efficient cutting-edge Innovative Materials for Future Products

/ Health Research application-oriented efficient

3 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

polymer coatings Investigation of new hybrid coatings with self-healing properties Characterization of

Time Line Bronze Age ~ 3600 600 BC Raman Effect Discovery

4 Time Line Bronze Age ~ BC Raman Effect Discovery Innovative 1928 Devices 2012 Sir Chandrasekhara Venkata Raman

5 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

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

6 Raman Intensity (a.u.) Sol-Gel Process FT-Raman Spectroscopy Hydrolysis of rganoalkoxysilanes e Vinyltriethoxysilane Wavenumbers (cm -1 ) 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

Hydrolysis of rganoalkoxysilanes e Vinyltriethoxysilane 650 672 1600 1400 1200 1000 800 600 400

7 ~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 Wavenumbers [cm -1 ] PMMA Substrate ptical axis z Wavenumbers [cm -1 ]

8 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) Wavenumbers [cm -1 ] EtCH3 Et Si Et Et H Dipentaerythritolpentaacrylate (DPEPA) Control of curing reactions Determination of conversion (acrylate: 75%; vinylsilane only 35% )

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)

9 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 UV exposure (s) 420

Evidence of dependance between coating s microhardness and organic cross-linking Inorganic network is not

10 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 Wellenzahlen [cm -1 ] 1260 H 2 C CH U159 U160 U161 U162 U163 U164 WVTR >> 0,01 WVTR < 0,01 6m2D52h 3m1D 3m2D52h 6m1D 6m2D4h 3m2D4h Aushärtung Higher cross-linking!

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

Self-Healing Principle Two layers containing capsules with reactive compounds Layer 1 + catalyst Layer 2 + monomer Micro-Raman-Spectroscopy Reactive compound -

11 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

- reference Reactive compound encapsulated in layer 2 Capsule wall + reactive

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

12 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:

Reactive compound Layer 1= Catalyst Reaction product in scratch after damage = Polymer

13 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:

electrochromic switch - Modified oxidised - Reduced - xidised Study of

14 Investigation of structural changes upon artificial weathering Raman-Intensität [a. u.] 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 ) Härtungsverfahren Curing 2 2 Härtungsverfahren Curing 3 3 n(cc) Helps to identify the best process Wellenzahlen [cm -1 ]

] 1659 1150 1113 535 1462 1613 1441 904 949 1297 1003 Influence of the curing parameters on the weathering stability of the resin Phenolformaldehyde

15 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 Vaterite Aragonite Calcite Vaterite Calcite Aragonite ,5 1 1, Distance from the Ca 2+ Source [mm] Wave Number [cm -1 ]

polyacrylamide matrices showed that the formation of calcium carbonate is significantly influenced by the gel matrix 9 8 7 Vaterite

16 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 Pottery 1: carbon black (amorphous) Pottery 2: Graphite (hexagonal) Ring: Diamond (cubic) Pottery Wavenumbers [cm-1] Ring

Reconstruction of ancient commercial routes, cultural exchange and know-how 20000

17 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 Potassium acetate (fan shaped) Calcium formate Wellenzahlen [cm -1 ] Potassium acetate + Calcium acetate

highly sensitive glass sensor "Schwamige Kristalle" Fächer Kristallanhäufung Rechtecke Nadelförmige

18 Raman Intensität [willk. Einheit] 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) Wellenzahlen [cm -1 ]

glasses Perfect conservation of the glass with a hybrid polymer layer (RMCER )

19 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:

Sabine Amberg-Schwab, Angela Amthor, Dr. Gerhard Schottner, Dr.

20 How to find us Fraunhofer-Institut für Silicatforschung ISC Neunerplatz 2 / Würzburg / Germany Tel [email protected] Bronnbach Branch Bronnbach 28 / Wertheim Phone [email protected] Fraunhofer Center for High Temperature Materials and Design Gottlieb-Keim-Straße 60 / Bayreuth Phone [email protected] Project Group Materials Recycling and Resource Strategies IWKS Brentanostraße 2 / Alzenau Rodenbacher Chaussee 4 / Hanau/Wolfgang Phone [email protected] Bilder: Fraunhofer ISC

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.

Back to Basics Fundamentals of Polymer Analysis

Back to Basics Fundamentals of Polymer Analysis Using Infrared & Raman Spectroscopy Molecular Spectroscopy in the Polymer Manufacturing Process Process NIR NIR Production Receiving Shipping QC R&D Routine