Surface Charge Modification of Nano-Sized Silica Colloid

Khoa N. Pham; Damian Fullston; Kwesi Sagoe-Crentsil

doi:10.1071/CH07138

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Surface Charge Modification of Nano-Sized Silica Colloid

Khoa N. Pham ^A ^B , Damian Fullston ^A and Kwesi Sagoe-Crentsil ^A

+ Author Affiliations

- Author Affiliations

^A CSIRO Manufacturing and Materials Technology, CSIRO, Graham Road, Highett VIC 3190, Australia.

^B Corresponding author. Email: Khoa.Pham@csiro.au

Australian Journal of Chemistry 60(9) 662-666 https://doi.org/10.1071/CH07138
Submitted: 1 May 2007 Accepted: 6 July 2007 Published: 11 September 2007

Abstract

The surface of commercial 30-nm colloidal silica particles were modified by reaction with functional silanes. The high specific surface area and reactivity of the particles, due to their small size, makes the process susceptible to irreversible aggregation not found previously with larger particles. The present study compares surface charge results from amino silanes with one or three alkoxy groups. Measurements of the zeta potential as a function of pH, and gelation kinetics shed light on the mechanism of surface charge changes from the modification. Instability in suspensions before and after the surface modification is also studied using a new data analysis technique from simple light-scattering equipment. Experimental results show very stable particles are obtained by amino silane surface modification. Factors affecting susceptibility of small particles to irreversible aggregation caused by a non-aqueous solvent or high concentration of a trialkoxy silane, including the large number of reactive silanol groups in the surface gel layer of the particles, are discussed.

References

Surface Charge Modification of Nano-Sized Silica Colloid

Abstract

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