Mahant Sunandan, Snider Jefferson R, Petters Sarah S, Petters Markus D
Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, California 92521, United States.
Center for Environmental Research and Technology (CE-CERT), University of California Riverside, Riverside, California 92507, United States.
J Phys Chem Lett. 2024 Jul 25;15(29):7509-7515. doi: 10.1021/acs.jpclett.4c01415. Epub 2024 Jul 17.
The amorphous phase state of suspended nanoparticles affects their atmospheric lifetimes and environmental impact. Influence of relative humidity and chemical composition on the glass-to-liquid transition is well-known. However, the influence of the particle size on the phase transition remains uncertain. Here we show experimental data that probe the amorphous phase transition of suspended sucrose particles as a function of particle size. The depression in glass-transition temperature follows the Gibbs-Thomson or Keesom-Laplace predicted proportionality of Δ ∝ for particles 100-700 nm in diameter, but the proportionality changes to Δ ∝ for smaller sizes. Literature data for glass-transition temperature depression in thin films and nanoconfined compounds show similar and strong deviations from the expected behavior. While the observed proportionalities remain incompletely understood, the results here provide evidence that the deviation from Δ ∝ is not attributable to substrate effects.
悬浮纳米颗粒的非晶相状态会影响它们在大气中的寿命以及对环境的影响。相对湿度和化学成分对玻璃态到液态转变的影响是众所周知的。然而，粒径对相变的影响仍不确定。在此，我们展示了探测悬浮蔗糖颗粒非晶相变作为粒径函数的实验数据。对于直径为100 - 700 nm的颗粒，玻璃化转变温度的降低遵循吉布斯 - 汤姆逊或基索姆 - 拉普拉斯预测的比例关系Δ ∝ ，但对于更小的粒径，比例关系变为Δ ∝ 。薄膜和纳米限域化合物中玻璃化转变温度降低的文献数据显示出与预期行为类似且强烈的偏差。虽然观察到的比例关系仍未完全理解，但此处的结果提供了证据，表明与Δ ∝ 的偏差并非归因于基底效应。
