微反应器内Stöber法可控制备SiO_(2)微球  

The controllable preparation of SiO_(2) microspheres by Stöber method in the microreactor

作　　者：余杨屏 杨梅[1] 李明芝[1,2] 陈光文 Yangping YU;Mei YANG;Mingzhi LI;Guangwen CHEN(Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian,Liaoning 116023,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院大连化学物理研究所,辽宁大连116023 [2]中国科学院大学,北京100049

出　　处：《过程工程学报》2023年第6期908-917,共10页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:22178336)。

摘　　要：采用微反应器与间歇反应器串联策略,实现了反应物料的快速混合及陈化时间的灵活调变,基于St?ber法可控合成了SiO_(2)微球。通过X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)对样品的物相和形貌进行了表征。结果表明,SiO_(2)微球的平均粒径及粒径分布取决于TEOS水解反应及硅酸盐单体缩聚反应间的竞争,同时还受反应前期物料的混合速率的显著影响。当陈化温度从25℃增高至75℃,SiO_(2)微球平均粒径从472 nm减小至200 nm,单分散性变化不大。当氨水浓度从0.8 mol/L增加至5.6 mol/L时,SiO_(2)微球平均粒径从34 nm增大至261 nm,单分散性变好。当水浓度增加至35.6 mol/L或TEOS浓度增加至1.0 mol/L时,溶液中发生多次成核或持续成核现象,使得SiO_(2)微球的单分散性急剧变差。提高雷诺数或缩小通道内径有利于获得单分散SiO_(2)微球。SiO_(2)microspheres were synthesized in a controlled manner via St?ber method by using a microreactor and a batch reactor in series to achieve rapid mixing of the reactant and flexible adjustment of the aging time.The phase and morphology of the as-prepared SiO_(2)were characterized by X-ray powder diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),and transmission electron microscope(TEM).The results showed that the mean particle size and dispersity of the SiO_(2)microspheres depended on the competition between the tetraethyl orthosilicate(TEOS)hydrolysis reaction and the silanol monomer condensation reaction,and were also significantly influenced by the mixing rate of reactants in the initial period.The monomer addition model was employed to explain the experimental results.When the aging temperature increased from 25℃to 75℃,the mean particle size of SiO_(2)microspheres decreased from 472 nm to 200 nm,with little change in dispersity.Because the reaction rates of TEOS hydrolysis and silanol monomer condensation increased with the increasing aging temperature,the supersaturation degree of silanol monomer immediately exceeded the critical supersaturation for homogeneous nucleation at higher aging temperatures.A large number of nuclei was formed,causing the formation of smaller microspheres.When the concentration of aqueous ammonia was increased from 0.8 mol/L to 5.6 mol/L,the mean particle size of SiO_(2)microspheres increased from 34 nm to 261 nm,and the dispersity became better.At higher ammonia concentration,more ethoxyl groups were hydrolyzed in a single TEOS molecule to produce silanol monomers with more silanol groups.This kind of silanol monomers could condense into siloxane networks at a faster rate,leading to larger particle sizes.When the water concentration increased to 35.6 mol/L or the TEOS concentration increased to 1.0 mol/L,multiple nucleation or continuous nucleation occurred in the solution,resulting in a dramatic deterioration of the dispersity of SiO_(2)microspheres.Increasing

关 键 词：微反应器 SiO_(2)微球 Stober法 平均粒径 单分散性 

分 类 号：TQ127.2[化学工程—无机化工]