(551e) Effect of Attractive Graft-Matrix Interactions on the Dispersion and Aggregation of Polymer Grafted Particles in Polymer Nanocomposites- a Theory and Simulation Study

In polymer nanocomposites (PNCs) comprised of grafted nanoparticles in a polymer matrix, tailoring the graft and matrix polymers is a way to tune the effective inter-particle interactions and morphology. In this talk we present our work [1] using molecular simulations and theory showing how increasingly attractive graft-matrix interactions affect the interpenetration of matrix and graft chains (termed as grafted layer wetting) and the dispersion/aggregation of grafted particles in the matrix. Past work by our group on similar systems has shown that wetting/dewetting and dispersion/aggregation are two distinct phase transitions, former a continuous one and the latter a first-order transition as a function of graft-matrix interactions. In this work we find that as the graft-matrix attraction increases, the graft chains extend and matrix chains increasingly wet the grafted layer, leading to larger and harder grafted particles compared to analogous PNCs with athermal graft-matrix interactions. Simultaneously, the PNC structure changes from an aggregated/dispersed morphology dictated by the entropic limit to a dispersed morphology due to favorable weak graft-matrix attraction, and finally, to a correlated fluid of hard grafted particles at stronger graft-matrix attraction.

[1] A. Kulshreshtha and A. Jayaraman, Dispersion and Aggregation of Polymer Grafted Particles in Polymer Nanocomposites Driven by the Hardness and Size of the Grafted Layer Tuned by Attractive Graft–Matrix Interactions, Macromolecules, 2020 53 (4), 1302-1313