Laboratory of Polymer Materials, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
Materials Engineering Centre (MEC), WMG, University of Warwick, Coventry CV4 7AL, UK.
Molecules. 2019 Jun 3;24(11):2106. doi: 10.3390/molecules24112106.
Different techniques of grafting polymer chains to filler surfaces are often employed to compatibilise filler and polymer matrices. In this paper the influence of graft length and graft density on the state of dispersion, crystallisation and rheological properties of poly(ε-caprolactone) (PCL)/silica (SiO) nanocomposites are reported. Grafted silica nanoparticles were prepared through polymerisation of PCL from the nanoparticle surface. Graft length was controlled by the reaction time, while the grafting density was controlled by the monomer-to-initiator ratio. Grafted nanoparticles were mixed with PCL of different molecular weights and the state of dispersion was assessed. Different matrix-to-graft molecular weight ratios resulted in different states of dispersion. Composites based on the higher molecular weight matrix exhibited small spherical agglomerates while the lower molecular weight matrix revealed more sheet-like microstructures. The state of dispersion was found to be relatively independent of graft length and density. Under quiescent conditions the grafts showed increased nucleation ability in the higher molecular weight PCL, while in the lower molecular weight matrix the effect was less pronounced. Rheological experiments showed an increase in viscosity with increased filler content, which was beneficial for the formation of oriented structures in shear-induced crystallisation.
为了改善填料与聚合物基体的相容性，通常采用将聚合物链接枝到填料表面的不同技术。本文报道了接枝链长度和接枝密度对聚己内酯（PCL）/二氧化硅（SiO）纳米复合材料的分散状态、结晶和流变性能的影响。通过从纳米颗粒表面聚合 PCL 制备接枝二氧化硅纳米颗粒。通过反应时间控制接枝链长度，通过单体与引发剂的比例控制接枝密度。将接枝纳米颗粒与不同分子量的 PCL 混合，评估分散状态。不同的基体与接枝的分子量比导致不同的分散状态。基于较高分子量基体的复合材料表现出较小的球形团聚体，而较低分子量基体则呈现出更多的片状微观结构。发现分散状态相对独立于接枝链长度和密度。在静止条件下，接枝在较高分子量 PCL 中表现出增强的成核能力，而在较低分子量基体中，这种影响不太明显。流变学实验表明，随着填料含量的增加，粘度增加，这有利于在剪切诱导结晶中形成取向结构。
