Synthesis and technological processing of hybrid organic-inorganic materials for photonic applications Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Julius-Maximilians-Universität Würzburg vorgelegt von Pélagie Declerck aus Chambray-lès-Tours, Frankreich Würzburg 2010 i. Index of abbreviations.………………………………………...……………………..…….5 ii. Definitions……………………………………………………………...……………..……7 ii.1 Water ratio r………………..…………………….………………………...………..…...7 ii.2 NMR notations for silicon species……………….……………..…………......…………7 ii.3 NMR notations for 13C and 1H………….…………….………...…..……...……………8 1 1. Introduction……………..……………………………...…………………….…9 2. Theoretical background…………..………………………………..………..12 2.1 Sol-gel process……..……………………...…………………………….………...12 2.1.1 Background of the sol-gel chemistry……………………………….....…….…...13 2.1.1.1 Chemical reactions…………………………………………………..………..……13 2.1.1.2 Chemical reactivity of metal alkoxides………………...…………….…....………14 2.1.2 Hybrid organic-inorganic materials……….………………………..…………..16 2.1.2.1 Class I materials………………..…………..………………………………………17 2.1.2.2 Class II materials…………………………………………………..…………..…..19 2.1.3 Organically modified silicon alkoxides…………………………..……...………22 2.1.3.1 Organic-inorganic hybrid polymeres..………………………………………..……22 2.1.3.2 Organically modified silicon alkoxides and transition metal alkoxides.….....…….25 2.2 Refractive index………………………………………….....…………………….27 2.2.1 Refractive index of materials……………………………..……………………...27 2.2.1.1 Inorganic oxidic materials………………………………...…...…………………..27 2.2.1.2 Organic materials……………………………………...…………………..….……29 2.2.1.3 Organic-inorganic hybrid polymers………………...………………………….…..34 2.2.2 Refractive index measurement………………………………………..…………36 2.2.2.1 Abbé refractometer………………………………………………………..……….37 2.2.2.2 Prism coupler…………………………………………………………………..…..37 2.2.2.3 Ellipsometry………………………..……………..………………………..………38 2.2.2.4 Transmission spectroscopy……………………………………...…………...…….40 2.3 Photon-induced organic polymerization………………………………..……….42 2.3.1 One-photon polymerization process…………………...……………..…………43 2.3.2 Two-photon polymerization process……………………...….…….…………....47 3. Experimental part……………………………….…………..……..…………51 3.1 Methods and instrumentation……………………………………..…………….51 3.1.1 Nuclear magnetic resonance spectroscopy (NMR) in solution…….….……….51 3.1.2 31P solid-state Magic Angle Spinning NMR………….……………………..…..52 2 3.1.3 Fourier-transform infrared spectroscopy…………………………..……...…...52 3.1.4 Micro-Raman spectroscopy…………………………………………………..….52 3.1.5 Ultraviolet, visible, and near-infrared spectroscopy………………………..….53 3.1.6 Ellipsometry……………………………………..………………………………..53 3.1.7 X-ray diffraction……………..…………………………………………………...53 3.1.8 Profilometry...…………….………...…………………………………………….54 3.1.9 Scanning-electron microscopy…………………………………..……………….54 3.1.10 Optical Microscopy……………………………………..………………………..54 3.2 Syntheses of inorganic-organic hybrid materials…………………………...….54 3.2.1 Solvents and chemicals…….…………………………………….….……………54 3.2.2 Resins synthesized without complexing ligands…….…………………………..55 3.2.2.1 Resins synthesized with one organo-alkoxysilane………………………..……….55 3.2.2.2 Resins synthesized with two organo-alkoxysilanes…………………………......…56 3.2.3 Complexed titanium alkoxide and organo-alkoxysilanes-based resins……….57 3.2.4 Resins based on organophosphorus precusors…………………………...……..58 3.3 Technological processing…………………………………………………..……..59 3.3.1 Coatings without UV exposure.……………………...…………………….…….59 3.3.2 Coatings with UV exposure…...……………...…………...………………..…….63 4. Results and discussion…………………………………………………..……71 4.1 Charaterization of the resins…………………………………………..………...71 4.1.1 Characterization of the organo-alkoxysilanes by multi-nuclei NMR spectroscopy……………………………..……………………………………..…71 4.1.1.1 [3-(Methacryloyloxy)propyl]trimethoxysilane and styrylethyltrimethoxysilane…………………………………………………....…..71 4.1.1.2 The alkoxy exchange reaction…………..…………………………………………75 4.1.1.3 Hydrolysis reactions of [3-(methacryloyloxy)propyl]trimethoxysilane and styrylethyltrimethoxysilane…………..………………………………....……...….79 4.1.2 Resins synthesized without complexing ligand……………………………..…..84 4.1.2.1 Resins synthesized with one organo-alkoxysilane………………..……...….…….84 3 4.1.2.1.1 [3-(methacryloyloxy)propyl]trimethoxysilane used as organo-alkoxysilane…..….84 4.1.2.1.2 Styrylethyltrimethoxysilane used as organo-alkoxysilane……………………..…..96 4.1.2.2 Resins based on three components……………………..………………………...106 4.1.2.2.1 [3-(methacryloyloxy)propyl]trimethoxysilane used as polymerizable organo- alkoxysilane…………………………………………………………..…………..106 4.1.2.2.2 Styrylethyltrimethoxysilane used as polymerizable organo-alkoxysilane……..…113 4.1.3 Resins with complexing ligand…………………………………………………115 4.1.3.1 Synthesis based on titanium precursor chelated with acetylacetone……………..115 4.1.3.2 Synthesis based on titanium oxo-cluster used as precursor………………………116 4.1.4 Resins containing organophosphorus precursors……………………………..121 4.1.5 Discussion of the synthesized resins….…………………………….…...……...128 4.2 Patterning of the resins…………………………………………………………131 4.2.1 The UV lithography process……………………………………………………131 4.2.1.1 Resins based on low titanium content……………………………………………132 4.2.1.2 Resins based on high titanium content….………..………………………………145 4.2.1.3 Resins containing complexing ligands………………………………………..….155 4.2.1.4 Resins containing organo-phosphorus precursors……………………….…….…157 4.2.2 The two-photon absorption process……………………………………………158 5. Summary……………………………………………………...………………..163 6. Summary in German……………………..…………………………………166 7. References……………...………………………………………………………169 8. Annex……………………………………………………………….….……….179 8.1 Annex 1: Other resins synthesized during this work ……………..…….……179 8.2 Annex 2: Calculation of k and k’………………………………………….……182 8.2 Annex 3: Emission spectra of the lamp from the mask aligner………………183 4 i. Index of abbreviations 2PP two-photon polymerization 3D three-dimensional ACAC acetylacetone AIBN 2,2-azobisisobutyronitril AOM acousto-optical modulator APTMS acryloxypropyltrimethoxysilane BAF 9,9-bis(4-aminophenyl) fluorine BAPS 2,2-bis(4-[4-aminophenoxy]phenyl)sulfone BPADA bisphenol A dianhydride BS beam splitter BU butanone CCD charge-coupled device CL complexing ligand CTE coefficient of thermal expansion Eq. equation dB decibel DC degree of conversion DEPT distortionless enhancement by polarization transfer dil. dilution DLW direct laser writing DMDMS dimethyldimethoxysilane DMDES dimethyldiethoxysilane DPD diphenylsilanediol DPDMS diphenyldimethoxysilane DPPA diphenylphosphinic acid DPDM S diphenyldimethoxysilane ECET [2-(3,4-epoxycyclohexyl)ethyl]trimetoxysilane FT- Fourier-transform GLYMO 3-(glycidyloxypropyl)trimethoxysilane HSP Hansen solubility parameters ID idendification numbers IR infrared ISC Fraunhofer-Institut für Silicatforschung, Würzburg 5 LO longitudinal optical MA methacrylic acid MAS-NMR Magic angle spinning nuclear magnetic resonance MAEAA 2-(methacryloyloxy)ethyl acetoacetate MEMO [3-(methacryloyloxy)propyl]trimethoxysilane MEMS microelectromechanical system(s) MEPA 2-(methacryloyloxy)ethyl phosphate mol-% molar percentage MP 4-methyl-2-pentanone no. number NA numerical aperture n.d. not determined NIR near-infrared NMR nuclear magnetic resonance ODA oxydianiline PA propylacetate PC photonic crystal PMDA pyromellitic dianhydride PMMA polymethylmethacrylate PPA phenylphosphonic acid ppm parts per million p-VBPA para-vinylbenzylphosphonic acid ref. reference RIE reactive ion etching SEM scanning electron microscopy SETMS styrylethyltrimethoxysilane SMDES styrylmethyldiethoxysilane TBAF tetrabutylammonium fluoride hydrate TEOS tetraethoxysilane THF tetrahydrofurane Ti(OBu)4 titanium butoxide Ti(OEt)4 titanium ethoxide i Ti(OPr )4 titanium isopropoxide Ti(OMe)4 titanium methoxide Ti(OPr)4 titanium propoxide 6 TM transition metal TMO transition metal oxide TMS tetramethylsilane TO transversal optical UV ultraviolet VIS visible WP wave plate wt.-% weight percent Zr(OEt)4 zirconium ethoxide Zr(OPr)4 zirconium propoxide ii. Definitions ii.1 Water ratio r In order to perform hydrolysis reactions necessary for some of the syntheses, water was added directly or mixed with the catalyst e.g. hydrochloric acid. The water content used in the syntheses is defined by the water ratio r. It is equal to the molar quantity of water added with respect to the molar quantity of water needed for a complete condensation reaction. For example, in a mixture based on 1 mol [3-(methacryloyloxy)propyl]trimethoxysilane (MEMO) and 1.5 mol H2O, the water ratio is equal to 1. For titanium, the coordination number may range from 4 to 6. Within the framework of this thesis, the calculation of the water ratio was based on a coordination number equal to 4. For example, in a mixture based on 1 mol titanium ethoxide (Ti(OEt)4) and 2 mol H2O, the water ratio is then close to 1. ii.2 NMR notations for silicon species 29Si-NMR spectroscopy was used for the refinement of the chemical environment of Si atoms by analyzing the chemical shifts of the signals. Notably, information on the silicon species such as their degree of condensation or hydrolysis can be determined. Since many different styles of notation have been used for polyorgano-alkoxysilanes in the literature, the notation style used in this thesis for the analysis of the 29Si NMR spectra will be described. Widely accepted are the notations M, D, T, and Q (mono, di, tri, and quaternary), which denote the number of oxygen substitutions at the silicon atom. For example, MEMO which contains three methoxy groups, is labeled T, or diphenylsilanediol