Compatibility/incompatibility in surface-modified, aggregated, precipitated silica nanocomposites*

Industrially relevant products often display a complex multi-level hierarchical, nano- to macro- scale structure. Control over this complex multi-hierarchical structure can be achieved through manipulation of filler-polymer compatibility/incompatibility such as by varying the silanol surface density, by chemically-tailoring the surface, and by grafting low molecular weight polymers. These modifications control dispersion and the associated emergent multi-hierarchy. Kinetic dispersion in reinforced elastomers has been likened to thermal dispersion leading to a pseudo-thermodynamic model.[1,2] The dispersion of modified fillers is quantified using this approach. These interactions can be classified as weak and strong depending on the presence of correlations. Interactions and dispersion are modeled using a random-phase or a modified Born-Green approach. Surface alteration was linked to the emergence of a multi-hierarchy. From the mesh size and packing of an emergent network, the state of dispersion and the interaction potential for coarse-grain simulations were determined.

[1] Y. Jin et al., Polymer (Guildf.) 129, 32 (2017)
[2] A. McGlasson et al., submitted to Macromolecules (2019)