Adrjanowicz K, Kaminski K, Koperwas K, Paluch M
Institute of Physics, University of Silesia, ulica Uniwersytecka 4, 40-007 Katowice, Poland.
NanoBioMedical Centre, Adam Mickiewicz University, ulica Umultowska 85, 61-614 Poznan, Poland.
Phys Rev Lett. 2015 Dec 31;115(26):265702. doi: 10.1103/PhysRevLett.115.265702. Epub 2015 Dec 22.
Dielectric relaxation studies for model glass-forming liquids confined to nanoporous alumina matrices were examined together with high-pressure results. For confined liquids which show the deviation from bulk dynamics upon approaching the glass transition (the change from the Vogel-Fulcher-Tammann to the Arrhenius law), we have observed a striking agreement between the temperature dependence of the α-relaxation time in the Arrhenius-like region and the isochoric relaxation times extrapolated from the positive range of pressure to the negative pressure domain. Our finding provides strong evidence that glass-forming liquid confined to native nanopores enters the isochoric conditions once the mobility of the interfacial layer becomes frozen in. This results in the negative pressure effects on cooling. We also demonstrate that differences in the sensitivity of various glass-forming liquids to the "confinement effects" can be rationalized by considering the relative importance of thermal energy and density contributions in controlling the α-relaxation dynamics (the E(v)/E(p) ratio).
对限制在纳米多孔氧化铝基质中的模型玻璃形成液体进行了介电弛豫研究，并结合了高压结果。对于在接近玻璃化转变时表现出与本体动力学偏差的受限液体（从Vogel-Fulcher-Tammann定律转变为Arrhenius定律），我们观察到在Arrhenius类区域中α弛豫时间的温度依赖性与从正压范围外推到负压域的等容弛豫时间之间存在显著一致性。我们的发现提供了有力证据，即一旦界面层的迁移率被冻结，限制在天然纳米孔中的玻璃形成液体就会进入等容条件。这导致了冷却时的负压效应。我们还证明，通过考虑热能和密度贡献在控制α弛豫动力学中的相对重要性（E(v)/E(p)比），可以解释各种玻璃形成液体对“限制效应”的敏感性差异。
