Bunkin Nikolai F, Astashev Maxim E, Bolotskova Polina N, Kozlov Valeriy A, Kravchenko Artem O, Nagaev Egor I, Okuneva Maria A
Department of Fundamental Sciences, Bauman Moscow State Technical University, 2-nd Baumanskaya Street 5, 105005 Moscow, Russia.
Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova Street 38, 119991 Moscow, Russia.
Polymers (Basel). 2022 Jun 22;14(13):2542. doi: 10.3390/polym14132542.
The temporal dynamics of luminescence from the surface of Nafion polymer membranes have been studied. In fact, the polymer membrane was soaked in liquids with different contents of deuterium. The test liquids were ordinary (natural) water (deuterium content equal to 157 ppm) and deuterium-depleted water (deuterium content is equal to 3 ppm). Simultaneously with the excitation of luminescence, the Nafion plate was irradiated with ultrasonic pulses, having a duration of 1 μs. The ultrasonic waves were generated with different repetition rates and amplitudes, and irradiated the surface of Nafion in the geometry of grazing or normal incidence. Luminescence regimes were studied when the membrane was irradiated with one ultrasonic wave (one piezoelectric transducer) or two counter-propagating waves (two piezoelectric transducers). It turned out that ultrasonic waves, which fall normal to the membrane interface, do not affect the dynamics of luminescence. At the same time, in the case of ultrasonic irradiation in the grazing incidence geometry, sharp jumps in the luminescence intensity occur, and the behavior of these jumps substantially depends on the mode of irradiation: one or two piezoelectric transducers. This allows for control of the dynamics of luminescence from the polymer surface. In accordance with this model, the possibility of altering the luminescence dynamics is due to the effect of unwinding the polymer fibers from the surface toward the liquid bulk upon soaking. It is important that such unwinding does not occur in deuterium-depleted water, which was confirmed in a direct experiment with dynamic light scattering from polydisperse aqueous suspensions of Nafion nanometer-sized particles; these suspensions were prepared in ordinary water and deuterium-depleted water. Thus, ultrasonic irradiation affects the dynamics of luminescence only when Nafion is swollen in ordinary water; in the case of deuterium-depleted water this effect is missed.
研究了Nafion聚合物膜表面发光的时间动态。实际上，将聚合物膜浸泡在具有不同氘含量的液体中。测试液体为普通（天然）水（氘含量等于157 ppm）和贫氘水（氘含量等于3 ppm）。在激发发光的同时，用持续时间为1 μs的超声脉冲照射Nafion板。以不同的重复率和振幅产生超声波，并以掠射或垂直入射的几何形状照射Nafion表面。研究了用一个超声波（一个压电换能器）或两个反向传播的波（两个压电换能器）照射膜时的发光状态。结果表明，垂直于膜界面入射的超声波不会影响发光动态。同时，在掠射入射几何形状的超声照射情况下，发光强度会出现急剧跳跃，并且这些跳跃的行为很大程度上取决于照射模式：一个或两个压电换能器。这使得可以控制聚合物表面发光的动态。根据该模型，改变发光动态的可能性是由于浸泡时聚合物纤维从表面向液体本体展开的效应。重要的是，在贫氘水中不会发生这种展开，这在对Nafion纳米级颗粒的多分散水悬浮液进行动态光散射的直接实验中得到了证实；这些悬浮液是在普通水和贫氘水中制备的。因此，只有当Nafion在普通水中溶胀时，超声照射才会影响发光动态；在贫氘水的情况下，这种效应不存在。
