General Strategies for Nanoparticle Dispersion

TLDR

Particle dispersion in polymeric materials is challenging, often causing phase separation and agglomeration, and even thermodynamically stable dispersions can be inaccessible without proper processing, especially for fullerene in linear polymers. The study demonstrates that nanoparticle dispersion in polymeric liquids is improved when the polymer’s radius of gyration exceeds that of the nanoparticle. Dispersed nanoparticles swell the polymer chains, increasing the polymer radius of gyration with nanoparticle volume fraction, and this entropically unfavorable swelling is counterbalanced by an enthalpic gain from increased molecular contacts at the nanoparticle surfaces.

Abstract

Traditionally the dispersion of particles in polymeric materials has proven difficult and frequently results in phase separation and agglomeration. We show that thermodynamically stable dispersion of nanoparticles into a polymeric liquid is enhanced for systems where the radius of gyration of the linear polymer is greater than the radius of the nanoparticle. Dispersed nanoparticles swell the linear polymer chains, resulting in a polymer radius of gyration that grows with the nanoparticle volume fraction. It is proposed that this entropically unfavorable process is offset by an enthalpy gain due to an increase in molecular contacts at dispersed nanoparticle surfaces as compared with the surfaces of phase-separated nanoparticles. Even when the dispersed state is thermodynamically stable, it may be inaccessible unless the correct processing strategy is adopted, which is particularly important for the case of fullerene dispersion into linear polymers.