Modified porous glass with silane coupling reagents as an ion-exchange membrane

Chiang, Tzu-Hang; Nakamura, Asao; Toda, Fujio

doi:10.1016/0040-6090(89)90273-3

Cited by 2 publications

(1 citation statement)

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“…This approach would require a surface of silica rich with amines that will react with a polyfunctional epoxide introduced in the mesopores. It is known that amine-functionalized glass can be obtained by treatment with APTES . A similar approach would also work well for our purposes, but post-treatment of silica hydrogels with APTES unnecessarily introduces several time-consuming wash steps.…”

Section: Resultsmentioning

confidence: 96%

Cross-linking Amine-Modified Silica Aerogels with Epoxies: Mechanically Strong Lightweight Porous Materials

et al. 2005

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The mesoporous surfaces of TMOS-derived silica aerogels have been modified with amines by copolymerization of TMOS with APTES. The amine sites have become anchors for cross-linking the nanoparticles of the skeletal backbone of the aerogel by attachment of di-, tri-, and tetra-functional epoxies. The resulting conformal coatings increase the density of the native aerogels by a factor of 2−3 but the strength of the resulting materials may increase by more than 2 orders of magnitude. Processing variables such as the amount of APTES used to make the gels, the epoxy type and concentration used for cross-linking, and the cross-linking temperature and time were varied according to a multivariable design-of-experiments (DOE) model. It was found that while elastic modulus follows a similar trend with density, maximum strength is attained neither at the maximum density nor at the highest concentration of −NH2 groups, suggesting surface saturation effects. Aerogels cross-linked with the trifunctional epoxide always show improved strength compared with aerogels cross-linked with the other two epoxides under identical conditions. Solid 13C NMR studies show residual unreacted epoxides, which condense with one another by heating cross-linked aerogels at 150 °C.

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Section: Resultsmentioning

confidence: 96%