The development of tuning parameters to influence the response behavior of polymer-based nanodevices is investigated by the addition of NaClO₄ or Mg(ClO₄)₂ to adjust the swelling degree of poly(N-isopropylmethacrylamide) thin films under different vapor atmospheres. By leveraging the cononsolvency effect of the polymer in a mixed vapor of water and acetone, a contraction of the preceding water-swollen films is induced. The relation between the macroscopic and the molecular processes is elucidated by static and time-resolved time-of-flight neutron reflectometry, as well as by in situ Fourier transform infrared spectroscopy. It is found that the addition of NaClO₄ strongly enhances the film thickness response for swelling and contraction, which, therefore, allows the tuning of the film toward stronger responses. Mechanistically, D₂O–amide bonds are formed during swelling and become perturbed upon vapor exchange. Thereby, the D₂O–amide interactions are reduced continuously, while acetone–amide interactions develop, accompanied by increasing amide–amide interactions during the film contraction.

中文翻译：

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盐介导的 PNIPMAM 薄膜的 Cononsolvency 响应行为的调节


通过添加 NaClO₄ 或 Mg（ClO₄）₂ 来调节聚（N-异丙基甲基丙烯酰胺）薄膜在不同蒸汽气氛下的膨胀程度，研究了影响聚合物基纳米器件响应行为的调谐参数的开发。通过利用聚合物在水和丙酮混合蒸气中的溶解效应，诱导前面的水溶胀薄膜收缩。宏观过程和分子过程之间的关系通过静态和时间分辨飞行时间中子反射法以及原位傅里叶变换红外光谱法来阐明。研究发现，NaClO₄ 的添加强烈增强了膜厚对膨胀和收缩的反应，因此，这允许将膜调整为更强的响应。从机制上讲，D₂O-酰胺键在溶胀过程中形成，并在蒸汽交换时受到干扰。因此，D₂O-酰胺相互作用不断减少，而丙酮-酰胺相互作用发展，伴随着薄膜收缩过程中酰胺-酰胺相互作用的增加。