Carrillo Jan-Michael Y, Sakwa-Novak Miles A, Holewinski Adam, Potter Matthew E, Rother Gernot, Jones Christopher W, Sumpter Bobby G
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
Computer Science and Mathematics Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
Langmuir. 2016 Mar 22;32(11):2617-25. doi: 10.1021/acs.langmuir.5b04299. Epub 2016 Mar 4.
The structure and dynamics of a model branched polymer was investigated through molecular dynamics simulations and neutron scattering experiments. The polymer confinement, monomer concentration, and solvent quality were varied in the simulations and detailed comparisons between the calculated structural and dynamical properties of the unconfined polymer and those confined within an adsorbing and nonadsorbing cylindrical pore, representing the silica based structural support of the composite, were made. The simulations show a direct relationship in the structure of the polymer and the nonmonotonic dynamics as a function of monomer concentration within an adsorbing cylindrical pore. However, the nonmonotonic behavior disappears for the case of the branched polymer within a nonadsorbing cylindrical pore. Overall, the simulation results are in good agreement with quasi-elastic neutron scattering (QENS) studies of branched poly(ethylenimine) in mesoporous silica (SBA-15) of comparable size, suggesting an approach that can be a useful guide for understanding how to tune porous polymer composites for enhancing desired dynamical and structural behavior targeting carbon dioxide adsorption.
通过分子动力学模拟和中子散射实验研究了一种模型支化聚合物的结构和动力学。在模拟中改变了聚合物的受限情况、单体浓度和溶剂质量，并对无约束聚合物以及限制在吸附和非吸附圆柱形孔内的聚合物（代表复合材料的二氧化硅基结构支撑）的计算结构和动力学性质进行了详细比较。模拟结果表明，在吸附圆柱形孔内，聚合物的结构与作为单体浓度函数的非单调动力学之间存在直接关系。然而，对于在非吸附圆柱形孔内的支化聚合物，非单调行为消失。总体而言，模拟结果与对尺寸相当的介孔二氧化硅（SBA - 15）中的支化聚（乙烯亚胺）进行的准弹性中子散射（QENS）研究结果高度吻合，这表明该方法可为理解如何调整多孔聚合物复合材料以增强针对二氧化碳吸附的所需动力学和结构行为提供有用指导。
