基于分子动力学模拟研究聚合物链排列对多层聚合物薄膜阻隔性能的影响

通过微纳层叠挤出技术制备聚丙烯(PP)多层膜,利用分子动力学模拟从微观分子链取向状态探究多层结构对PP薄膜阻隔性能的影响。实验结果表明,与PP单层膜相比,PP多层膜的阻隔性能明显提升,其氧气透过系数和水蒸气透过系数分别下降了23.9%和86.4%。通过分子动力学模拟构建了PP单层膜和多层膜的渗透率模型,通过渗透率模型比较了小分子通过PP单层膜和多层膜的扩散路径。结果发现,与PP单层膜相比,PP多层膜界面处的二维分子链取向使得其内部小分子扩散路径更加曲折,这是PP多层膜具有良好阻隔性能的重要原因之一。同时,通过PP单层膜与多层膜力学性能的对比实验分析,验证了渗透率模型的准确性。

Effect of Polymer Chains Arrangement on Barrier Properties of Multilayer Polymer Films:A Molecular Dynamics Simulation

Polypropylene(PP) multilayer films were prepared by novel microlayer coextrusion technology. Molecular dynamics simulations were carried out to investigate the effect of multilayer nanostructures on the barrier properties of PP films from the perspective of microscopic molecular chain orientation. The experiments suggest that, compared with PP monolayer films, the barrier properties of PP multilayer films are significantly improved, with oxygen and water vapor transmission coefficients decreased by 23.9% and 86.4%, respectively. In order to explore the barrier properties of PP multilayer films from the perspective of microstructure, the permeability models of PP monolayer and multilayer films were investigated by molecular dynamics simulations. The small molecule diffusion paths through PP monolayer and multilayer films were compared using permeability models. The two-dimensional molecular chain orientation at the interface of PP multilayer films makes the small molecule diffusion paths more tortuous compared to those of PP monolayer films. This is one of the important reasons for the excellent barrier properties of PP multilayer films. Simultaneously, the accuracy of the permeability models was verified by comparative experimental analysis between mechanical properties of PP monolayer and multilayer films.