近日，德国达姆施塔特工业大学的Thomas Blochowicz及其研究小组与丹麦罗斯基尔德大学的Jeppe C. Dyre等人合作并取得一项新进展。经过不懈努力，他们揭示材料老化过程中的时间可逆性。相关研究成果已于2024年1月26日在国际知名学术期刊《自然—物理学》上发表。
该研究团队利用动态光散射测量提供了一种全新的方法。他们利用多斑动态光散射探测到的强度波动的时间自相关函数，成功地确定了1-苯基-1-丙醇玻璃形成体在温度跃迁至接近玻璃化转变后的材料时间。更重要的是，当将这些波动视为材料时间的函数时，发现它们表现出稳态和可逆的特性。此外，研究人员还观察到胶体合成黏土硅酸镁锂和化学老化固化环氧树脂中，也存在材料时间可逆的散射光强度波动。
对老化二元系统的模拟监测势能进一步证实了材料时间的可逆性。这一研究不仅证明了材料时间的直接测量方法，而且揭示了在完全不同背景下老化的基本特性。这一发现对现有的老化理论提出了挑战。
据悉，物理老化是玻璃材料中由分子重排引起的不可逆过程的总称。这种老化过程涉及到材料时间的概念，它可以被视为时钟上测量的时间，但其速率随着玻璃的老化而变化。尽管物理老化已经得到了广泛的理论和实验研究，但至今尚未实现材料时间的实验测定。
附：英文原文
Title: Time reversibility during the ageing of materials
Author: Bhmer, Till, Gabriel, Jan P., Costigliola, Lorenzo, Kociok, Jan-Niklas, Hecksher, Tina, Dyre, Jeppe C., Blochowicz, Thomas
Issue&Volume: 2024-01-26
Abstract: Physical ageing is the generic term for irreversible processes in glassy materials resulting from molecular rearrangements. One formalism for describing such ageing processes involves the concept of material time, which may be thought of as time measured on a clock whose rate changes as the glass ages. Experimental determination of material time has so far not been realized, however. Here we show how dynamic light-scattering measurements provide a way forward. We determined the material time for an ageing sample of the glass-former 1-phenyl-1-propanol after temperature jumps close to the glass transition from the time-autocorrelation function of the intensity fluctuations probed by multispeckle dynamic light scattering. These fluctuations are shown to be stationary and reversible when regarded as a function of the material time. The glass-forming colloidal synthetic clay Laponite and a chemically ageing curing epoxy are also shown to display material-time-reversible scattered-light intensity fluctuations, and simulations of an ageing binary system monitoring the potential energy confirm material-time reversibility. In addition to demonstrating direct measurements of the material time, our findings identify a fundamental property of ageing in quite different contexts that presents a challenge to the current theories of ageing.
DOI: 10.1038/s41567-023-02366-z
Source: https://www.nature.com/articles/s41567-023-02366-z