Vanskeviče Ieva, Kinka Martynas, Banys Jūras, Macutkevič Jan, Schaefer Sebastien, Selskis Algirdas, Fierro Vanessa, Celzard Alain
Faculty of Physics, Vilnius University, Sauletekio 9/3, LT-10222 Vilnius, Lithuania.
Center for Physical Science and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania.
Polymers (Basel). 2024 Feb 22;16(5):603. doi: 10.3390/polym16050603.
This work presents the dielectric and ultrasonic properties of polydimethylsiloxane (PDMS) nanocomposites filled with titanium dioxide nanoparticles. The dielectric study was performed over a very broad range of frequencies (20 Hz-3 THz). The dielectric permittivity was almost frequency-independent in all the composites at room temperature over the whole range of measurement frequencies, and the dielectric losses were very low under these conditions (less than 2). The dielectric permittivity strongly increases with the nanoparticle concentration according to the Maxwell-Garnet model. Therefore, the investigated composites are suitable for various flexible electronic applications, particularly in the microwave and terahertz frequency ranges. Dielectric dispersion and increased attenuation of ultrasonic waves were observed at lower temperatures (below 280 K) due to the relaxation of polymer molecules at the PDMS/TiO interface and in the polymer matrix. The relaxation time followed the Vogel-Vulcher law, while the freezing temperature increased with the titanium dioxide concentration due to interactions between the polymer molecules and nanoparticles. The significant hysteresis in the ultrasonic properties indicated that titanium dioxide acts as a crystallization center. This is confirmed by the correlation between the hysteresis in the ultrasonic properties and the structure of the composites. The small difference in the activation energy values obtained from the ultrasonic and dielectric investigations is related to the fact that the dielectric dispersion is slightly broader than the Debye-type dielectric dispersion.
这项工作展示了填充有二氧化钛纳米颗粒的聚二甲基硅氧烷（PDMS）纳米复合材料的介电和超声特性。介电研究在非常宽的频率范围（20 Hz - 3 THz）内进行。在室温下，在整个测量频率范围内，所有复合材料的介电常数几乎与频率无关，并且在这些条件下介电损耗非常低（小于2）。根据麦克斯韦 - 加尼特模型，介电常数随纳米颗粒浓度显著增加。因此，所研究的复合材料适用于各种柔性电子应用，特别是在微波和太赫兹频率范围内。在较低温度（低于280 K）下，由于聚合物分子在PDMS/TiO界面和聚合物基体中的弛豫，观察到了介电色散和超声波衰减的增加。弛豫时间遵循沃格尔 - 富尔彻定律，而冻结温度由于聚合物分子与纳米颗粒之间的相互作用随二氧化钛浓度增加。超声特性中的显著滞后表明二氧化钛充当结晶中心。超声特性中的滞后与复合材料结构之间的相关性证实了这一点。从超声和介电研究中获得的活化能值的微小差异与介电色散比德拜型介电色散略宽这一事实有关。
