Control of Particle Dispersion with Autophobic Dewetting in Polymer Nanocomposites

Good particle dispersion in polymer nanocomposites (PNCs) is often hampered by autophobic dewetting where the matrix polymers are expelled from the grafted polymer, generally believed to result in increased particle aggregation and enhanced mechanical properties in dilute particle regime. However, we found that autophobic dewetting with highly extended short-chain polymers improves/disrupts particle dispersity, strongly dependent on particle volume fraction. Under strong autophobic condition given with the high-molecular-weight ratio between the matrix, P, and grafted polymer, N, ( P / N ≫ 1), silica nanoparticles grafted with dopamine-modified poly(ethylene glycol) (DOPA-mPEG) brush polymer are dispersed in the PEG matrix by varying the surface grafting rate. In the dilute particle regime, we found that increasing grafting rate ironically improves particle dispersion and reduces the she…