Self-regulated flow control in microchannels by the modification of walls with stimuli-responsive polymer

近十年来，在芯片上制备微通道组成的微分析系统得到了极大的研究和广泛的应用。本文提出了一种复杂微通道流体控制的新方法。通过刺激改变其亲疏水特性的刺激响应聚合物被用于修饰通道壁。通过将硅烷偶联剂结合在玻璃壁上，然后将n -异丙基丙烯酰胺与具有能与目标化合物结合的官能团的单体进行水自由基共聚合，成功地实现了改性。我可以通过温度、盐或表面活性剂等刺激因素成功地控制表面润湿性。润湿性的改变会导致流体的开关或流动方向的改变。高疏水性的十八烷基硅烷与刺激响应性聚合物相结合，显著提高了材料的润湿性。此外，对粗糙度为亚微米级的表面进行改性对于获得高可湿性和拒水性的表面都是非常有效的。含有羧基或咪唑基团的聚合物可以根据酸碱条件改变亲疏水性。含有苯硼酸盐取代基的聚合物可以与糖结合，但对葡萄糖不起作用。另一方面，具有苯基硼酸酯和二甲氨基基团的聚合物的疏水性由于葡萄糖的存在而增加。这种刺激响应聚合物的改性将是制造葡萄糖响应型流量控制系统的有效手段。

In this decade, micro-analytical systems composing of fabricated micro-channels on chips has extremely investigated and applied to the wide areas. In the present study, a novel methodology for the fluid control complicate micro-channels was developed. The stimuli-responsive polymer that changes its hydrophilic-hydrophobic properties by stimuli was used to modify the wall of channels. The modification was successfully achieved by binding silane coupling agent on glass walls and the subsequent aqueous radical co-polymerization of N-isopropylacrylamide and a certain monomer having functional group that can bind to the objective compound. I could successfully control the surface wettability by stimuli such as temperature, salt, or surfactants. The wettability change results in the on-off of the stream or switching the flow direction. The contrast of the wettability was significantly improved by the modification with highly hydrophobic octadecylsilane accompanying with stimuli-responsive polymer. Furthermore, the modification onto the surfaces having sub-micro meter order of asperity was quite effective for obtaining-both of highly wettable and waters repellent surfaces. The polymer containing carboxyl or imidazole moieties can varied the hydrophilic-hydrophobic properties depending on the acid-alkaline conditions. The polymer including phenylborate substituents that can bind to sugar could not respond against glucose. On the other hand, the hydrophobicity of the polymer having the both of phenylborate and dimethylamino groups increased by the presence of glucose. The modification by such stimuli-responsive polymer will be effective for making glucose-responsive flow control system.