Microfluidic system based on porous silicon.

SUMMARY OF MAIN RESULTS

1.      Covalent immobilization of alkanes on porous silicon was successfully performed. It was demonstrated that due to high porous silicon activity no catalysts needed for covalent immobilization of alkanes.

2.      Two main pathways of silicon-surface modification were studied:

a)      silicon hydrosilylation

,  R = C8H17, C16H33

Scheme (A)

b)      silanisation of partly-oxidized silicon

, R = CH3, C8H17

Scheme (B)

 

3.      By DRIFT, FTIR and TPD-MS methods covalent nature (not adsorption) of chemical bond between silicon and alkane chain was proved.

4.      Conditions that may give stable for chromatography application particles postulated

 MAIN CONCLUSIONS

  1. It was demonstrated that pathway (A) is suitable for fresh porous silicon only, but pathway (B) acceptable for most porous silicon samples.

  2. Complete substitution of surface Si-H groups does not observed in any cases neither in hydrosilylation reaction nor in porous silicon oxidation.

  3. Partly oxidized silicon containing Si-H bonds is inactive in hydrosilylation reaction (A).

  4. Since unstable silicon framework is protected by siloxane layers,  materials obtained by silanisation according to the scheme (B) can be more stable in common chromatography environment then those obtained by scheme (A).

  5. Due to poor stability of Si-Si bond partial oxidation on porous silicon surface is needed, but this oxidation may increase size of silicon crystals and decrease permeability of the membrane, so optimal conditions leading to stable but suitable for chromatography silicon-base phase should be found.

  6. Geometry of flat silicon membrane limits application of it for solid-phase extraction (and may be affinity extraction) but not for chromatographic separation (chromatography).

Publications

  1. Study of Porous Silicon Nanostructures as Hydrogen Reservoirs
    Lysenko, V.; Bidault, F.; Alekseev, S.; Zaitsev, V.; Barbier, D.; Turpin, C.; Geobaldo, F.; Rivolo, P.; Garrone, E.;
    J. Phys. Chem. B. ; (Article); 2005; 109(42); 19711-19718.