Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
Mol Pharm. 2012 Jun 4;9(6):1559-69. doi: 10.1021/mp2004498. Epub 2012 May 15.
Broadband dielectric measurements were carried out in the supercooled as well as in the glassy state of two very important disaccharides: trehalose and sucrose. Multiple relaxation processes were observed. Above the glass transition temperatures of examined disaccharides structural relaxation of cooperative origin was detected, where in the glassy state more local motions (secondary modes) appeared. Our data were discussed in light of the findings reported by other groups. We pointed out that sample preparation might impact mobility and, thus, dielectric loss spectra in a significant way. Consequently, it may lead to misinterpretation of the dielectric relaxation processes. Moreover, impact of physical aging and pressure on dynamics of two secondary relaxation processes observed in the glassy state of trehalose and sucrose has been investigated. Additionally, we have demonstrated that, in contrast to the calorimetric measurements (DSC), activation energies of the β- and γ-relaxation processes observed in the glassy state of sucrose and trehalose do not change as a result of physical aging. Finally, we found out that the β-relaxation process slows down as pressure increases. We interpreted this fact in view of increasing rigidity of the structures of disaccharides.
海藻糖和蔗糖，在过冷和玻璃态下进行了宽带介电测量。观察到了多个弛豫过程。在被研究的二糖的玻璃化转变温度以上，检测到了协同起源的结构弛豫，在玻璃态下出现了更多的局部运动（次级模式）。我们的数据是根据其他小组的研究结果进行讨论的。我们指出，样品制备可能会以显著的方式影响移动性，从而影响介电损耗谱。因此，这可能导致对介电弛豫过程的误解。此外，还研究了物理老化和压力对在海藻糖和蔗糖玻璃态下观察到的两种次级弛豫过程的动力学的影响。此外，我们还证明了，与量热测量（DSC）相反，在蔗糖和海藻糖玻璃态下观察到的β-和γ-弛豫过程的活化能不会因物理老化而改变。最后，我们发现随着压力的增加，β-松弛过程会减慢。我们根据二糖结构的刚性增加来解释这一事实。
