选择性紫外曝光法修饰微流控芯片用于制备高度均一的单乳液和复乳液

Preparation of Highly Uniform Single and Double Emulsions with Microfluidic Chips Modified by Region-selective UV Irradiation

利用选择性紫外曝光法对聚二甲基硅氧烷(PDMS)微流控芯片通道内壁进行了部分亲/疏水改性,通过接触角和原子力显微镜对改性表面进行表征,并利用改性后的芯片制备出了高度均一的单乳液和复乳液.结果表明,在芯片的非曝光区域,光引发剂二苯甲酮使PDMS表面粗糙且保持疏水性,接触角为101o;而在曝光区域,由于聚合形成的聚丙烯酸交联到PDMS上使其表面光滑且具有亲水性,接触角为62o,形成的亲/疏水特性可维持30d以上.利用改性后芯片制备的大豆油、三羟甲基丙烷丙烯酸酯和氟碳油3种单乳液的粒径变异系数均低于3%,而复乳液外径和内径的变异系数分别为3.5%和2.9%.

A novel region-selective hydrophilic modification approach by UV irradiation was used to change the surface property in PDMS-based microfluidic chip. The surface properties of microchannels before and after modification were characterized by contact angle measurement and atomic force microscope. Thereafter, microfluidic chip region-selectively modified by this method was applied to prepare highly uniform single and double emulsions. The results demonstrated that in the un-exposed region, original hydrophobic PDMS surface tended to be very coarse and hydrophobic with contact angle 101° after photoinitiator solution treatment. But in the UV-exposed region, poly（acrylic acid） was coated on the surface, leading to a hydrophilic surface with contact angle 62°. In addition, those hydrophilic and hydrophobic features were able to maintain at least for 30 d. Using the modified microfluidic chips, three kinds of highly uniform O/W single droplets, soybean oil, trimethylolpropane triacrylate and fluorocarbon oil, were prepared with coefficient variation （CV） below 3%. Uniform W/O/W double emulsions were also successfully prepared with CV of the outer and inner diameters at 3.5% and 2.9%, respectively.