关键词: 聚(N-异丙基丙烯酰胺), 锂藻土, 纳米复合凝胶微球, 杨氏模量, 弹性力学性能

Abstract: Temperature-responsive poly(N-isopropylacrylamide) （PNIPAM） nanocomposite hydrogel microspheres are successfully prepared by microfluidic technology using Laponite as crosslinker in this work. A simple micro-step uniaxial compression device is developed to study the elastic properties of PNIPAM/Laponite nanocomposite hydrogel microspheres，which only needs a programmed syringe to achieve the micro-compression deformation and a precision electronic balance to measure the applied force. The images of compression process of a single hydrogel microsphere are captured by a side-view optical system. The results show that PNIPAM/Laponite nanocomposite hydrogel microspheres exhibit elastic deformation at both 25℃ and 37℃，and the obtained force-deformation experimental data fit well with the Hertz Theory. The Laponite content in the nanocomposite hydrogel microspheres significantly affects their mechanical properties and temperature-responsive behaviors. With the increase of Laponite content，the thermo-responsive volume change degree of the nanocomposite hydrogel microspheres decreases. But the Young’s modulus of PNIPAM/Laponite nanocomposite hydrogel microspheres increases with the increase of the Laponite content at both 25℃ and 37℃. Furthermore，the Young’s modulus of PNIPAM/Laponite nanocomposite hydrogel microspheres at 37℃ is much larger than that at 25℃ due to the thermo-induced volume shrinkage and rigidity increase. The results in this study provide a valuable guidance for designing smart hydrogel microspheres for practical applications.

Key words: poly(N-isopropylacrylamide), Laponite, nanocomposite hydrogel microspheres, Young’s modulus, elastic mechanical properties