Leibniz-Institut für Polymerforschung Dresden e.V. , Hohe Straße 6, 01069 Dresden, Germany.
Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln , 207 Othmer Hall, Lincoln, Nebraska 68588, United States.
Langmuir. 2018 Feb 20;34(7):2448-2454. doi: 10.1021/acs.langmuir.7b03919. Epub 2018 Feb 5.
We report investigations on the salt sensitivity of the thermoresponsive behavior of PNIPAAm brushes applying the quartz crystal microbalance coupled with spectroscopic ellipsometry technique. This approach enables a detailed study of the optical and mechanical behavior of the polymer coatings. Additional conclusions can be drawn from the difference between both techniques due to a difference in the contrast mechanism of both methods. A linear shift of the phase-transition temperature to lower temperatures with the addition of sodium chloride was found, similar to the behavior of free polymer chains in solution. The thermal hysteresis was found to be decreased by the addition of sodium chloride to the solution, hinting to the interaction of the ions with the amide groups of the polymer, whereby the formation of hydrogen bonds is hindered. The results of this study are of relevance to the application of PNIPAAm brushes in biological fluids and demonstrate the additional potential of the ion sensitivity besides the better known thermosensitivity.
我们应用石英晶体微天平结合光谱椭圆术技术研究了 PNIPAAm 刷的温敏行为的盐敏感性。这种方法能够详细研究聚合物涂层的光学和机械行为。由于两种方法的对比机制不同，因此可以从两种技术的差异中得出其他结论。发现随着氯化钠的加入，相转变温度线性向低温移动，类似于溶液中游离聚合物链的行为。发现加入氯化钠会降低热滞后，这暗示了离子与聚合物的酰胺基团相互作用，从而阻碍了氢键的形成。这项研究的结果与 PNIPAAm 刷在生物流体中的应用有关，并证明了除了更好地研究热敏感性外，离子敏感性还有额外的应用潜力。
