Thermodynamic Principles of Precipitation Polymerization and Role of Fractal Nanostructures in the Particle Size Control

Abstract

The effect of the solvent on the morphology andthe particle size of the polymer materials obtained by precipitationpolymerization is not yet understood from a physical chemicalperspective. Clarifying the effect of the solvent is an importantissue to understand the thermodynamic principles of precipitationpolymerization and forward the engineering aspects. In this work,we use the scaling theory to deduce the thermodynamic equationsthat control the phase separation process and particle size inprecipitation polymerization at constant T and P. To do so,precipitation polymerization has been undertaken in three steps:(I) coil-to-globule transition, (II) phase separation, and (III)growth stage. The model is then used to analyze the effect of the solvent in precipitation polymerization at constant T and P. Toprove the model, we focus on analyzing correlations between the theoretical curves and the experimental curves obtained fromprecipitation polymerization of a model polymeric system in different solvents and show that we can faithfully reproduce theexperimental curves by using the theoretical equations. Finally, we exploit the thermodynamic principles of heterogeneous nucleationon fractal surfaces to develop a novel methodology based on precipitation polymerization in the presence of small concentrations offractal nanostructures and show how this new approach is able to reduce the particle size up to eight times below the values obtainedfrom conventional precipitation polymerization