Experimental validation of a mathematical model for the evolution of the particle morphology of waterborne polymer-polymer hybrids: Paving the way to the design and implementation of optimal polymerization strategies

Abstract

Polymer-polymer composite nanoparticles allow both the improvement of the performance in stablished applications of waterborne polymer dispersions and targeting new applications that are out of reach of currently available products. The performance of these materials is determined by the particle morphology. To open the way to process optimization and on-line control of the particle morphology, the capability of the recently developed model to predict the evolution of the particle morphology during seeded semibatch emulsion polymerization process was evaluated. Structured polymer particles were synthesized by copolymerization of styrene and butyl acrylate (St-BA) on methyl methacrylate and butyl acrylate (MMA-BA) copolymer seeds of different Tgs. The model captured well the effect of process variables on the evolution of the particle morphology, opening the way to the design and implementation of optimal strategies.

Forces Driving the Development of Particle Morphology of Waterborne Polymer Dispersions

“…In this article, the forces driving the development of the particle morphology in a seeded emulsion polymerization where a water soluble initiator is used and the second stage polymer (Polymer 2) is more hydrophobic than the seed polymer. Experimental evidence [24] shows that clusters of Polymer 2 are formed at the surface of the seed. The evolution of these clusters was studied by integrating the Navier-Stokes equations using COMSOL Multiphysics.…”

“…So far, only one isolated cluster has been considered. However, the experimental results [24] show that the surface of the particle is covered by many clusters. Therefore, the interaction between them should be considered.…”

“…The second one is that it is much more efficient computationally, which is a necessary condition for optimization and on-line control. The model has been validated for polymer-polymer [24] and polymerinorganic [25] systems. In both cases, the validation was based on the good agreement between the predictions of the model and the images of the particle morphology obtained by conventional transmission electron microscopy (TEM) using stained samples, which was good.…”

“…The preferential formation of Polymer 2 near the surface of the particle was attributed to the radical concentration profile formed as a consequence of the use of a water soluble initiator. Actually, the experimental results available for the evolution of the particle morphology during the seeded semicontinuous emulsion polymerization [24] show that, initially, many small clusters of Polymer 2 were formed on the surface of the particle and that later they grew by polymerization and coagulation, undergoing at the same time some penetration into the polymer particle (Figure 2). The higher degree of penetration of the surface clusters into softer particles can be attributed to the lower resistance that the polymer in the seed opposed to the migration of the clusters towards the equilibrium morphology (inverted coreshell).…”

Inline Raman Spectroscopy of an Emulsion Copolymerization in an Industrial Pilot Plant Using Indirect Hard Modeling

“…The goal of the synthesis is to produce polymer particles with a distinct non-equilibrium morphology, i.e., the shape of the polymer particles, formed due to the incompatibility of the seed polymer phase and the second stage polymer phase. The chosen recipe is reported in [21] as case 1. Only the second-stage polymerization is considered in this work.…”