微流控液滴软模板制备二氧化钛中空微球

Synthesis of hollow titania microspheres by using microfluidic droplet-template

应用微流控液滴技术合成功能材料已发展成为一个新兴领域。本文以夹流结构微流控芯片产生的微液滴作为软模板,以液滴模板界面处发生的水解反应生成二氧化钛球壳,并经后续脱核处理,制备二氧化钛中空微球。采用激光诱导荧光成像、扫描电镜等手段对微球形貌结构进行了分析表征。结果表明,通过控制微流控芯片液滴合成条件,可以得到壁厚约2μm的二氧化钛中空微球。这种以微流控液滴为模板的合成方法简单灵活,若与其他材料改性方法相结合,有望实现对更多元、更复杂功能微球材料的制备,并进一步拓宽其在光电和催化剂材料领域的应用。

Droplet-based microfluidics is of great interest due to its particular characteristics compared with the conventional methods,such as reduced reagent consumption,rapid mixing,high-throughput,shape controlled,etc.A novel method using microfluidic droplet as soft template for the synthesis of hollow titania microspheres was developed.A typical polydimethylsiloxane（PDMS） microfluidic device containing ＂flow-focusing＂ geometry was used to generate water/oil（W/O） droplet.The mechanism for the hollow structure formation was based on the interfacial hydrolysis reaction between the continuous phase containing titanium butoxide precursor and the dispersed containing water.The continuous phase mixed with butanol was added in the downstream of the channel after the hydrolysis reaction.This step was used for drawing the water out of the microgels for further hydrolysis.The microgels obtained through a glass pipe integrated were washed,dried under vacuum and calcined after aging for a certain time.The fluorescence and scanning electron microscope（SEM） image of the microspheres indicated the hollow structure and the thickness of the shell.In addition,these microspheres with thin shell（about 2 μm） were apt to rupture and collapse.Droplet-based microfluidic offered a gentle and size-controllable manner to moderate this problem.Moreover,it has potential applications in photocatalysis combined with some modification realized on the chip simultaneously.