Spatiotemporal Characteristics of the Hierarchical Relaxation Dynamics for Topological Soft Nanoparticles

Soft nanoparticles (SNPs) bring great opportunities for broad fields by introducing shape deformability to NPs and launching the dimensionality of the structural unit topology for polymers. However, the intrinsic characteristics that govern SNPs' unique properties and functions are still vague. Herein, sub-1 nm polyhedral oligomeric silsesquioxane (POSS) units are covalently assembled into model SNP systems with monodispersed structures and diverse topologies. With the help of dielectric and nuclear magnetic resonance examinations, the hierarchical relaxation dynamics can be identified as the rotation of the phenyl group, the subdiffusive dynamics of terminal POSSs, and the diffusion of SNPs. Rheology and thermal analysis directly correlate the relaxation dynamics to SNPs' mechanical and thermal properties, which unravel the molecular mechanisms of the topology effect and supramolecular interaction in regulating materials' viscoelasticity. Our work lays solid groundwork for understanding the structure-dynamics-viscoelasticity relationships and further spurs the rational design of emergent SNP materials with desired properties.