Development of bio-science materials by designing porous structure and surface property of oxide gels.

以乙酸为催化剂，在水溶性高分子存在下，通过烷氧基硅烷水解制备了具有可控连通孔的微米级硅胶。凝胶化溶液的时间分辨激光光散射测量显示，当由旋节机制的相分离和溶胶-凝胶转变几乎同时发生时，开发的互连结构。在蒸发溶剂之前，在不同温度下将凝胶浸泡在具有不同浓度和与凝胶片的体积比的氨溶液中，导致纳米范围的孔结构在适当的干燥和热处理之后被改性成直径高达20 nm的明确限定的中孔。氨浓度越高，浸泡温度越高，孔径越大。当用较小体积的溶剂对凝胶片进行浸泡时，结构变化被延迟。该结果表明，二氧化硅从湿凝胶表面溶解到外部溶剂中是由于二氧化硅的溶解和再沉淀而导致的整个结构演变的速率决定步骤。浸泡处理可以完全消除凝胶样品中的微孔。对由此制备的具有双孔结构的二氧化硅整料作为色谱柱材料进行评价。在用十八烷基和甲基配体对亲水性硅胶表面进行化学改性之后，用聚合物包覆棒状整料，并将其装配到LC装置中。整体柱对烷基苯类化合物的分离因子与常规填充珠柱基本相同，但在相同的样品流速下，所用压力仅为常规填充珠柱的1/2 ~ 1/3。

Silica gels with controlled interconnected pores in micrometer range have been prepared by hydrolyzing alkoxysilane in the presence of a certain kind of water-soluble polymer using acetic acid as a catalyst. The time-resolved laser light scattering measurements of gelling solution revealed that the interconnected structure is developed when the phase separation by the spinodal mechanism and the sol-gel transition take place almost concurrently. The soaking of gels, prior to the evaporation of the solvent, in ammonia solutions with various concentration and volume ratio to the gel piece at various temperatures resulted in the modification of nanometer range pore structures into well-defined mesopores up to 20nm in diameter, after appropriate drying and heat-treatment. The higher the ammonia concentration, and the higher the soaking temperature, the larger the pore size became. When the soaking was carried out with smaller volume of solvent against a gel piece, the structural change was retarded. This result indicates that the dissolution of silica from the wet gel surface into the external solvent is the rate determining step of the whole structure evolution due to dissolution and re-precipitation of silica. The soaking treatment could completely eliminate the micropores in the gel specimen. An evaluation of silica monoliths having double pore sturcures thus prepared was carried out as a chromatographic column material. After chemical modification of hydrophilic silica gel surface with octadecyl and methyl ligands, a rod shaped monolith was clad with polymer, and was equipped to an LC apparatus. The separation factors for alkylbenzens of the monolithic column was almost the same as that of conventional packed beads column, however, the applied pressure for the same sample flow rate was reduced to 1/2 to 1/3 of conventional one.