Photopatternable Di-ureasil−Zirconium Oxocluster Organic−Inorganic Hybrids As Cost Effective Integrated Optical Substrates

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• 作者：Daniela C. Oliveira ; Andreia G. Macedo ; Nuno J. O. Silva ; Celso Molina ; Rute A. S. Ferreira ; Paulo S. André ; Karim Dahmouche ; Veró ; nica De Zea Bermudez ; Younes Messaddeq ; Sidney J. L. Rib
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：June 10, 2008
• 年：2008
• 卷：20
• 期：11
• 页码：3696 - 3705
• 全文大小：1085K
• 年卷期：v.20,no.11(June 10, 2008)
• ISSN：1520-5002

文摘

Organic−inorganic hybrids containing methacrylic acid (McOH, CH₂c="http://pubs.acs.org/images/entities/dbd_2.gif">C(CH₃)COOH)) modified zirconium tetrapropoxide, Zr(OPrⁿ)₄, classed as di-ureasil−zirconium oxo-cluster hybrids, have been prepared and structurally characterized by X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), Fourier transform infrared (FT-IR) and Raman (FT-Raman) spectroscopies, ²⁹Si and ¹³C nuclear magnetic resonance (NMR), and atomic force microscopy (AFM). XRD and SAXS results have pointed out the presence of Si- and Zr-based nanobuilding blocks (NBBs) dispersed into the organic phase. Inter-NBBs correlation distances have been estimated for the pure di-ureasil and a model compound obtained by hydrolysis/condensation of Zr(OPrⁿ)₄:McOH (molar ratio 1:1): d_Si ≈ 26 c="http://pubs.acs.org/images/entities/plusmn.gif"> 1 &#xc5; and d_Zr ≈ 16 c="http://pubs.acs.org/images/entities/plusmn.gif"> 1 &#xc5;, respectively. In the case of the di-ureasil−zirconium oxo-cluster hybrids, these distances depend on the Zr relative molar percentage (rel. mol. Zr %) (d_Si ranges from 18 to 25 &#xc5; and d_Zr from 14 to 23 &#xc5;, as the rel. mol. Zr % increases from 5 to 75), suggesting that the Si- and Zr-based clusters are interconstrained. Complementary data from FT-IR, FT-Raman, ²⁹Si and ¹³C NMR, and AFM support to a structural model where McOH-modified Zr-based NBBs (Zr-OMc) are present over the whole range of composition. At low Zr-OMc contents (rel. mol. Zr % <30) the clusters are well-dispersed within the di-ureasil host, whereas segregation occurs at the 0.1 µm scale at high Zr-OMc concentration (rel. mol. Zr % = 50). No Zr−O−Si heterocondensation has been discerned. Monomode waveguides, diffractions gratings, and Fabry−Perot cavities have been written through the exposure of the hybrid monoliths to UV light. FT-Raman has shown that the chemical process that takes place under illumination is the polymerization of the methacrylate groups of the Zr-OMc NBBs. The guidance region in patterned channels is a Gaussian section located below the exposed surface with typical dimensions of 320 µm wide and 88 µm deep. The effective refractive index is 1.5162 (maximum index contrast on the order of 1 × 10⁻⁴) and the reflection coeficient of the Fabry−Perot cavity (formed by a grating patterned into a 0.278 cm channel) is 0.042 with a free spectral range value of 35.6 GHz.