Kang Eunsoo, Graczykowski Bartlomiej, Jonas Ulrich, Christie Dane, Gray Laura A G, Cangialosi Daniele, Priestley Rodney D, Fytas George
Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61614 Poznan, Poland.
Macromolecules. 2019 Jul 23;52(14):5399-5406. doi: 10.1021/acs.macromol.9b00766. Epub 2019 Jul 11.
Despite the growing application of nanostructured polymeric materials, there still remains a large gap in our understanding of polymer mechanics and thermal stability under confinement and near polymer-polymer interfaces. In particular, the knowledge of polymer nanoparticle thermal stability and mechanics is of great importance for their application in drug delivery, phononics, and photonics. Here, we quantified the effects of a polymer shell layer on the modulus and glass-transition temperature ( ) of polymer core-shell nanoparticles via Brillouin light spectroscopy and modulated differential scanning calorimetry, respectively. Nanoparticles consisting of a polystyrene (PS) core and shell layers of poly(-butyl methacrylate) (PBMA) were characterized as model systems. We found that the high of the PS core was largely unaffected by the presence of an outer polymer shell, whereas the lower of the PBMA shell layer decreased with increasing PBMA thickness. The surface mobility was revealed at a temperature about 15 K lower than the of the PBMA shell layer. Overall, the modulus of the core-shell nanoparticles decreased with increasing PBMA shell layer thickness. These results suggest that the nanoparticle modulus and can be tuned independently through the control of nanoparticle composition and architecture.
尽管纳米结构聚合物材料的应用日益广泛，但在受限条件下以及聚合物 - 聚合物界面附近，我们对聚合物力学和热稳定性的理解仍存在很大差距。特别是，聚合物纳米颗粒的热稳定性和力学知识对于其在药物递送、声子学和光子学中的应用至关重要。在此，我们分别通过布里渊光谱和调制差示扫描量热法量化了聚合物壳层对聚合物核壳纳米颗粒模量和玻璃化转变温度（ ）的影响。以由聚苯乙烯（PS）核和聚（甲基丙烯酸丁酯）（PBMA）壳层组成的纳米颗粒作为模型体系进行表征。我们发现，PS核的高 在很大程度上不受外部聚合物壳层存在的影响，而PBMA壳层较低的 则随着PBMA厚度的增加而降低。表面迁移率在比PBMA壳层的 低约15 K的温度下显现出来。总体而言，核壳纳米颗粒的模量随着PBMA壳层厚度的增加而降低。这些结果表明，可以通过控制纳米颗粒的组成和结构来独立调节纳米颗粒的模量和 。
