Hou, Lisong

Mennig, Martin

Schmidt, Helmut K.

Universaar

A novel sol-gel derived ORMOCER material as host for photochromic dyes

Acronym

Sm 1992132SecondSAAFR-H, O R.- LU_JX Meetinagontr,xtennded Abstnac'tsI-Jnder the patronage of theMinister for Research and Culture ofSaarlandLuxembourgSaarbrückenMetzNancvIntensive coursesSupported by the E,uropean community' (comn)ocrobe r 20 Lo 21 . 1gg2Saarbrücken, FRGf -"'-""'*"-!'17-,'-:'  * * *  i* * i2 ß  t  i*: lf f$fä':iEditor: Helmut SchmidtPublished byINM -  lnst i tu t  für  Neue Mater ia l ien gem.GmbHlm Stadtwald, Gebäude 43, 6600 Saarbrücken (FRG)Phone: +681/302-5013, Fax: +0681 1302-5223Apr i l  1993Cbpying of material in this book for internal or personaluse onlyPrinted in the Federal Republic of GermanyA novel sol_gel derived oRMocER material as host for photochromic dyes-Lisong Hou, M. N{ennig and H SchmidtInstitut fur Neue Materialien GmbH, w-6600 Saarbrücken, GermanyIn recent },ears, the inrportance of organic dyes used for various optical purposes has beenincreasing significantly. Among the others, fundamental and applied researches on photo-chromic dyes have been receiving more and more interest. one of the most importantaspects is the matrix which hosts the dyes. Dyes in liquid matrices (e g water, alcohol'chloroform etc.) usually suffer from undesirable aggregation which is responsible forconcentration quenching of the photochromic effect. Thus solid state matrices have beenpursued and exploited. Up to the present, horve'er, most of the research work on solidmatrices for photochromic dyes have been focussed on organic polymer systemslll'Although dye ag*egation is reduced to a certain extent another major limitation arises tothe long-term use of polymer matrices, i.e. lorv thermal and photochemical stability' Inorder to overcome this limitation it is advisable to use inorganic oxide matrices, rvhich arenot only thermally and photochemically but also dimensionally more stableThe low-temperature characteristics of the sol-gel process make the sol-gel derived gelsoffer 'exciting potentials as hosts for a rvide variety of dye molecules includingphotochromic dyes. D. Levy et al.[2] studied the photochromic properties of spiropyranesin three kinds of modified silica matrices prepared by the sol-gel process. Only one systemshowed normal photochromism J. I zink and B Dunn[3] doped spiropyranes in a Nzo;-Sio2-system using the bialkoxide ASE as the starting material rhey also doped 2,3'diphenylindenone oxide (Dplo)tal into three kinds of gels, i e Sioz, AsE and oRMosrLand found that both the photochromic intensity and the lifetime decrease gradually duringthe ageing and drying ProcessIn the present work, a novel sol-gel derived ORMOCER material has been developed as ahost for spirooxazines, one (So1) is commercially available (Ndrich Chemical Inc') andanother (So2) is a home-synthesized one with the spirooxazine molecules bonded to Si inthe silane molecules through -CH2-CHz-CH2-spacers. organically modified alkoxides, e'g'MTMS, ETES, GPTMS and DMDES or their mixtures were used as starting compounds'A two-step procedure , i.e. acid-catalysed hydrolysis and base-catalysed polyrnerisation,was used for the sol preparation. Coatings or monolithic gels have been successfullyobtained with this method by spraying and casting respectively'The colouring and fading processes of the dyes were monitored using a home-madeapparatus. A l00w Hg-lamp is used as the light source for tlV-irradiation and a He-Ne-laser (tr:633nm) is used as the monitoring light beam. The irradiation intensity on thesample surface is adjusted by a focussing system to mimic the intensity of st, ,hr(ca.3mW/cm2).The follorving experimental results have been obtained:Using the established preparation procedure, sols with different viscosit l, can be tail,rr.edby the introduction of dif lerent kinds and contents of additives, in response to diffcrentViscosity requirements for the preparation of coatings of certain thickness and preparationof shaped gels at desired imensions.Coatings and gels containing SO I are colourless at room temperature, b't thosecontaining SO2 have brown bottom colours. Although the fading speeds of thespirooxazines are about 2 times lowered by doping in the coatings and gels, they are stilltoo fast to measure the absorption peak r.l,avelength of their coloured states using theexisting spectrophotometer. Therefore the gels were cooled down to -20oC, thenirradiated b)' UV light to get staurated colouring and the absorption spectra weremeasured. In this rvay, the absorption peak wavelenghts have been determined to be 613and 614 nm respectively. This indicates that the Fle-Ne-laser is a fairly suitable probingl ight.Heat treatment rvas exerted to the coatings on glass slides up to 120"C. No signif icantdegradation of the photochromism was detected In addition, SO2 is more stable than SOIagainst heating.The photochromic absorption level of coatings rvith a thickness of ca. 500prm and the dyeconcentraion of lx10-3 moVI is similar to that of the dye solution in ethanol at aconcentration of 5xl0{ moVl (the maximum photochromism concentration) rvith a l0 mmoptical path. This implies that the aggregation problem is greatl l , improved (by about l0times) in these ORMOCER matrices.The mechanical properties of the matrix material remains to be further improved in orderto meet the requirements for practical use.Finally, the authors wish to express their thanks to Mr. J. Blau and lv{r B. lIoffrnann fortheir assistance to the experimental work.Referencest l l FI. Dürr and H. Bouas-Laurent, <<photochromism - molecules and systems>>Elsevier, I990, Amsterdamt2lt3lt4lD. Levy and D. Avnir,  J. Non-cryst. Sol ids, I  l3 (19g9) 137I . r zink and B Dunn, J. Mater. chem I (6) ( i 991) 903S. A. Yamanka, J. L Zink, B. Dunn, Preparation of sol-gel optics II, San Diego,r992

https://publikationen.sulb.uni-saarland.de/bitstream/20.500.11880/24525/1/sm199232.pdf

A novel sol-gel derived ORMOCER material as host for photochromic dyes

Abstract

Similar works

Full text

Available Versions

Universaar

Acronym