Esquivias Luis, de la Rosa-Fox Nicolás, Bejarano Mercedes, Mosquera Maria J
Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad de Cádiz, 11510 Puerto Real, Spain.
Langmuir. 2004 Apr 13;20(8):3416-23.
Crack-free monolithic gels were prepared from different mixtures of colloidal silica with a sol solution containing tetraethoxysilane, under powerful ultrasonic agitation (sonosol). Recently, information on the structure of these gels, inferred from N2 adsorption and mercury intrusion porosimetry, was presented. In the present paper, these data were used to construct structural models of the gels using Monte Carlo calculations on the basis of random close packing (RPC) premises. In addition, the structure of gels under study was investigated by transmission and scanning electron microscopy. The material can be described as a composite in which the sonogel is the matrix and the colloid particles the reinforcing phase. For low colloid content, the colloid forms discrete clusters, and the main structural characteristic of sonogels, i.e., a network of uniformly sized particles of approximately 3-4-nm radius, remains unmodified. However, for high colloid silica content, a multimode distribution appears, the structure is discontinuous, and only colloid aggregates larger than 100 nm are observed. For medium colloid content, aggregates of approximately 50-100 nm can be seen, but the sonogel structure extends throughout the whole material. By the processing method and election of a suitable precursor concentration, it is possible to design the composite for specific purposes.
在强力超声搅拌（声溶胶）下，由胶体二氧化硅与含有四乙氧基硅烷的溶胶溶液的不同混合物制备出无裂纹的整体凝胶。最近，展示了从N2吸附和压汞孔隙率法推断出的这些凝胶的结构信息。在本文中，这些数据被用于基于随机密堆积（RPC）前提，通过蒙特卡罗计算构建凝胶的结构模型。此外，通过透射电子显微镜和扫描电子显微镜研究了所研究凝胶的结构。该材料可被描述为一种复合材料，其中声凝胶是基体，胶体颗粒是增强相。对于低胶体含量，胶体形成离散的聚集体，而声凝胶的主要结构特征，即半径约为3 - 4纳米的均匀尺寸颗粒网络，保持不变。然而，对于高胶体二氧化硅含量，出现多峰分布，结构不连续，并且仅观察到大于100纳米的胶体聚集体。对于中等胶体含量，可以看到约50 - 100纳米的聚集体，但声凝胶结构贯穿整个材料。通过加工方法和选择合适的前驱体浓度，可以针对特定目的设计该复合材料。
