Controlled Nanoparticle Formation by Diffusion Limited Coalescence

TL;DR

This paper develops an analytical theory for predicting the size of polymeric nanoparticles formed during precipitation, emphasizing the roles of diffusion-limited coalescence, mixing, and polymer concentration.

Contribution

It introduces a universal scaling model linking nanoparticle size to mixing and polymer concentration, validated by experimental data.

Findings

Nanoparticle size scales with mixing time and polymer concentration.

The model accurately predicts experimental nanoparticle sizes.

Size control is achievable through manipulation of mixing conditions.

Abstract

Polymeric nanoparticles (NPs) have a great application potential in science and technology. Their functionality strongly depends on their size. We present a theory for the size of NPs formed by precipitation of polymers into a bad solvent in the presence of a stabilizing surfactant. The analytical theory is based upon diffusion-limited coalescence kinetics of the polymers. Two relevant time scales, a mixing and a coalescence time, are identified and their ratio is shown to determine the final NP diameter. The size is found to scale in a universal manner and is predominantly sensitive to the mixing time and the polymer concentration if the surfactant concentration is sufficiently high. The model predictions are in good agreement with experimental data. Hence the theory provides a solid framework for tailoring nanoparticles with a priori determined size.