Designing Novel\nAll-Polymer Nanocomposites with Pearl\nNecklace Chain Structure with High Strength, High Toughness, and Low\nHysteresis

Service performance can be significantly improved by\nadding nanofillers\ninto polymers. However, entropy effects and enthalpic interactions\nbetween traditional inorganic fillers and polymers impede the simultaneous\nattainment of high strength and strong toughness. Polymer-based soft\nnanoparticles (SNPs) have emerged as promising candidates for achieving\na balance between strength and toughness. To fully harness the deformability\npotential of SNPs and achieve superior mechanical performance, the\npearl necklace structure was designed by employing molecular dynamics\nsimulation. Compared to traditional all-polymer nanocomposite system\n(S<sub>T</sub>) composed of directly mixing polymer and SNPs, the\nSNPs in our novel system (S<sub>N</sub>) exhibit better dispersion\nand compatibility. Primitive path analysis revealed that the pearl\nnecklace chains endow a greater degree of penetration between SNPs\nand polymer. The confinement effects of cross-linking networks alter\nthe diffusion dynamics of SNPs embedded within polymer chains. The\nrestricted displacement fluctuation distance dfluctSNP of SNPs in the S<sub>N</sub> was obtained\nby the van Hove function <i>G</i><sub><i>s</i></sub>(<i>r</i>, Δ<i>t</i>), a typical\nlinear correlation between the dfluctSNP and the mesh size of the polymer matrix\ncross-linked network ⟨<i>L</i><sub>c</sub>⟩.\nThe distinctive structural and dynamic behaviors of the S<sub>N</sub> are prominently reflected in the macroscopic mechanical properties.\nStress decomposition analysis reveals that SNPs predominantly bear\nstress at low strain, whereas at high strain polymer dominates, akin\nto the reinforcement mechanism observed in dual polymer network of\nhydrogels. Moreover, SNPs within the S<sub>N</sub> exhibit greater\ndeformation and slower recovery rates compared to S<sub>T</sub>, resulting\nin a 21.3% reduction in hysteresis loss. The toughness of the composites\nwas evaluated through triaxial stretching. The S<sub>N</sub> exhibits\nmore uniform distribution of fibrils along the stretching direction,\nthereby enhancing crack resistance and increasing dissipated work\nby approximately 50% compared to S<sub>T</sub>. In summary, this proposed\nnovel pearl necklace structure opens a new avenue to balance the strength–toughness–hysteresis\nof polymer nanocomposites.