Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián, Spain.
J Chem Phys. 2009 Nov 28;131(20):204901. doi: 10.1063/1.3258857.
Quasielastic neutron scattering experiments (time-of-flight, neutron spin echo, and backscattering) on protonated poly(vinyl methyl ether) (PVME) have revealed the hydrogen dynamics above the glass-transition temperature. Fully atomistic molecular dynamics simulations properly validated with the neutron scattering results have allowed further characterization of the atomic motions accessing the correlation functions directly in real space. Deviations from Gaussian behavior are found in the high-momentum transfer range, which are compatible with the predictions of mode coupling theory (MCT). We have applied the MCT phenomenological version to the self-correlation functions of PVME atoms calculated from our simulation data, obtaining consistent results. The unusually large value found for the lambda-exponent parameter is close to that recently reported for polybutadiene and simple polymer models with intramolecular barriers.
准弹性中子散射实验（飞行时间、中子自旋回波和背散射）对质子化聚（甲基乙烯基醚）（PVME）的研究揭示了玻璃化转变温度以上的氢动力学。与中子散射结果进行了适当验证的全原子分子动力学模拟进一步表征了原子运动，直接在实空间中获取相关函数。在高动量转移范围内发现了与高斯行为的偏差，这与模式耦合理论（MCT）的预测相符。我们将 MCT 唯象版本应用于从模拟数据计算的 PVME 原子的自相关函数，得到了一致的结果。发现的 lambda 指数参数异常大，接近于最近报道的聚丁二烯和具有分子内势垒的简单聚合物模型的值。
