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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Transformation of CdS Colloids: Sols, Gels, and Precipitates
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Transformation of CdS Colloids: Sols, Gels, and Precipitates

机译：CdS胶体的转化：溶胶，凝胶和沉淀物

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Highly concentrated CdS colloid (about 30 wt %) are prepared in acetone through the grafting of 4-fluorophenylthiol at their surface. ~19F NMR measurements show that the controlled oxidation by an aqueous solution of hdyrogen peroxide leads to a mixture of dithiol and fluorosulfonate species. Aggregation of particles produces either transparent gels or opaque precipitates, depending on the nature and the concentration of the oxidant. The sol-gel transofrmation results from an aggregation mechanism, which requires the release of surface groups because of their interaction with water molecules. Considering the formation of mass-fractal clusters, small-angle X-ray scattering measurements show, at least in the first, that the growth kinetics is in agreement with the usual reaction limited cluster aggregation mechanism previously observed in the silica system. This can be followed by a saturated effect, enhanced at low water concentration, which is due to the poisoning of the surface by chemical groups produced by oxidation.
机译：通过在其表面接枝4-氟苯基硫醇，在丙酮中制备高浓度的CdS胶体（约30 wt％）。 〜19 F NMR测量显示过氧化氢过氧化氢水溶液的受控氧化导致二硫醇和氟代磺酸盐类的混合物。颗粒的聚集会产生透明的凝胶或不透明的沉淀物，具体取决于氧化剂的性质和浓度。溶胶-凝胶反渗透作用是由聚集机制产生的，由于与水分子的相互作用，需要释放表面基团。考虑到质量分数维团簇的形成，小角度X射线散射测量至少在第一阶段显示出生长动力学与先前在二氧化硅体系中观察到的通常的反应受限的团簇聚集机制相符。随后是饱和效应，在低水浓度下会增强，这是由于表面被氧化产生的化学基团所毒化所致。

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