Topological Design and Mechanical Manipulation of Matrix-Free Polymer Grafted Nanoparticles Driven by Bond Exchanging

Tailoring mechanical properties through bond exchange reactions (BERs) demands precise topological manipulation, yet accurately correlating structures and properties to complex topologies remains a challenge. This investigation delves into matrix-free polymer grafted nanoparticles (PGNPs) with dynamic covalent bonds and examines how topological control can modulate material properties. Through coarse-grained molecular dynamics simulations, the alterations in the grafted polymer uniformity (α) induced by BERs triggered by terminals of grafted polymers are examined. Innovative α-kinetics theoretical model is proposed to capture the temporal evolution of topologies and elucidate the significant influence of BER kinetics and initial topology. Additionally, the α-equilibrium theoretical model characterizes equilibrium topologies, revealing the geometric distribution of grafted polymers. The theoretical models are further extended to include scenarios beyond terminal-triggered BERs, affirming their comprehensive applicability. Subsequently, it is elucidated how specific topological configurations can significantly enhance toughness and reveal the intrinsic mechanisms, which enable the construction of structure-property relationships. In summary, this study not only addresses the experimental challenges in the topological characterization of PGNPs, but also underscores the importance of strategic topological design in determining material properties and advancing material science.