AN EFFECTIVE CROSS LINKING OF POLYMER LAYER ON MONODISPERSE, POLY(MALEIC ANHYDRIDE-STYRENE)-MODIFIED COLLOIDAL SILICA PARTICLES AND PROPERTIES OF THE COMPOSITE

摘要

The cross-linkings of the surface polymer layer on mono disperse, poly(maleic anhydride-styrene)-modified silica particles by the reaction with diisocyanate were studied. The extent of cross-linking was estimated by the weight decrease by immersing the particles in the buffer solution of pH 2.0, 4.0 and 9.0 at a room temperature for 24 h. The reaction of the polymer-modified silica with 1,6-diisocyanatohexane afforded relatively stable composite particles which lost less than 5 wt% of the polymer in aqueous solution in the pH range 2.0-9.0. The diisocyanate was a preferable cross-linker to 2,4-diisocyanatotoluene in terms of stability in acidic or basic aqueous solution. The flexibility of the crosslinker molecule possibly plays an important role in the cross-linking reaction. The carboxyl and amino groups were formed by treating the cross-linked composite particles with diluted HCl solution; 5-6 and 0.5-1.1 mu mol g(-1), respectively. The cross-linked composite particles exhibited the characteristic property of zeta-potential, -44 to -47 mV and -102 to -107 mV in a neutral aqueous solution and ethanol, respectively. [References: 18]