Jabbarzadeh Ahmad
Faculty of Engineering, School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney NSW 2006, Australia.
Sydney Nano Institute, The University of Sydney, Sydney NSW 2006, Australia.
Nanomaterials (Basel). 2019 Oct 16;9(10):1472. doi: 10.3390/nano9101472.
Controlling the crystallinity of hybrid polymeric systems has an important impact on their properties and is essential for developing novel functional materials. The crystallization of nanocomposite polymers with gold nanoparticles is shown to be determined by free space between nanoparticles. Results of large-scale molecular dynamics simulations reveal while crystallinity is affected by the nanoparticle size and its volume fraction, their combined effects can only be measured by interparticle free space and characteristic size of the crystals. When interparticle free space becomes smaller than the characteristic extended length of the polymer molecule, nanoparticles impede the crystallization because of the confinement effects. Based on the findings from this work, equations for critical particle size or volume fraction that lead to this confinement-induced retardation of crystallization are proposed. The findings based on these equations are demonstrated to agree with the results reported in experiments for nanocomposite systems. The results of simulations also explain the origin of a two-tier crystallization regime observed in some of the hybrid polymeric systems with planar surfaces where the crystallization is initially enhanced and then retarded by the presence of nanoparticles.
控制杂化聚合物体系的结晶度对其性能有重要影响，对于开发新型功能材料至关重要。含有金纳米颗粒的纳米复合聚合物的结晶过程表明，其结晶度由纳米颗粒之间的自由空间决定。大规模分子动力学模拟结果显示，虽然结晶度受纳米颗粒尺寸及其体积分数的影响，但它们的综合效应只能通过颗粒间自由空间和晶体的特征尺寸来衡量。当颗粒间自由空间小于聚合物分子的特征伸展长度时，由于受限效应，纳米颗粒会阻碍结晶过程。基于这项工作的研究结果，提出了导致这种受限诱导结晶延迟的临界粒径或体积分数的方程。基于这些方程得出的研究结果与纳米复合体系实验报道的结果一致。模拟结果还解释了在一些具有平面表面的杂化聚合物体系中观察到的两级结晶机制的起源，在这些体系中，结晶最初会增强，然后由于纳米颗粒的存在而受到抑制。
