Effect of organic modifiers on the thermo-optic characteristics of inorganic–organic hybrid material films

Abstract

The thermo-optic coefficient (dn/dT) of inorganic-organic hybrid material films prepared by the sol-gel process of organoalkylsilanes is measured using a prism coupler equipped with a hot stage. The effect of the organic modifier on the variation of dn/dT in inorganic-organic hybrid material films has been investigated. The value of dn/dT becomes more negative with increasing molecular weight of the organic modifier or with an increase in the proportion of modifier in the sample. On the other hand, dn/dT increases with an increase in the degree of organic photopolymerization. From these results, it can be seen that the value of dn/dT in these films can be varied between −0.83 × 10 −4 /°C to −2.43 × 10 −4 /°C by changing the organic modifier concentration and type.

Optical characteristics of photo-curable methacryl-oligosiloxane nano hybrid thick films

“…In the linear plot of the refractive index change against temperature, therefore, the thermo-optic coefficient (dn/dT) of the film can be calculated from its gradients. 7,18 As shown in Fig. 8, their dn/dTs are −2 × 10 −4 /°C, independent of the compositions, and are very close to other organic polymers.…”

“…The prism coupler (Pennington, Metricon 2010), equipped with an auto-controlled hot stage, was used to measure the temperature dependence of the refractive index (dn/dT) in the coating films. 7,18 The refractive index was measured at a temperature range of 30-90°C.…”

“…It has been reported that the photo-polymerization of the methacryl groups can increase the refractive index of the film through densification. 7,[9][10][11] The refractive index change of the film with low DPSD contents, therefore, becomes larger than those with high DPSD contents during photo-polymerization. This densification-induced refractive index change seems not to be negligible, in case of the coating films.…”

“…7,18,21 As the DPSD contents increase, the formation of the siloxane bond is promoted due to the further condensation reaction. The degree of polymerization of the methacryl group, on the other hand, is reduced by the steric effect, as shown in Fig.…”

“…5,6 They also possess some very fascinating features, such as their photo-curablility and their easily tunable optical characteristics. [7][8][9][10][11] A photo-curable HYBRIMER can be synthesized through the introduction of photo-active precursors, which usually contain C‫ס‬C bonds. One of these photocurable HYBRIMERs is the methacryl-oligosiloxane nano hybrid material (methacryl HYBRIMER) synthesized from 3-(trimethoxysilyl)propyl methacrylate (MPTS) and diphenylsilanediol (DPSD).…”