Effects of Cross-Linking on the Morphology of Structured Latex Particles. 1. Theoretical Considerations

Abstract

Cross-linking of the seed latex polymer introduces elastic forces into the thermodynamic analysis of the morphology of composite particles. By determining the elastic storage energy necessary to maintain a deformation within the seed latex particle (as in an occlusion of second-stage polymer), it can be combined with the interfacial energies internal to the particle and at its aqueous phase boundary to compute the total free energy of a specific particle morphology. At low levels of cross-linking it is found that the elastic and interfacial energies are of the same order of magnitude, with the final morphology determined by the balance between them. Elastic energies are dependent upon the state of deformation within the particle, and this makes the thermodynamic equilibrium morphology analysis dependent upon cross-link level, seed latex particle size, stage ratio (second polymer/seed polymer), and the interfacial tensions at the polymer/polymer and polymer/water interfaces. Computational results are presented which show the effects of each of these variables on the predicted morphology.

Polymer phase separation in composite latex particles. 1. Considerations for the nucleation and growth mechanism

“…We have done many investigations of latex particle morphology under conditions in which the polymer reactions are slow enough that phase separation achieves its thermodynamic equilibrium state [7][8][9][10][11][12][13][14][15]. In this state the final particle structure is determined by the minimization of the interfacial free energies of the various polymer interfaces within and at the extremity of the particle.…”

Recent Advances in the Emulsion Solvent Evaporation Technique for the Preparation of Nanoparticles and Nanocapsules

“…4d) engulfed in another material. Occluded structures (i.e., with multicores) are also possible morphologies and can be obtained as a kinetically trapped structure or as a thermodynamically favorable structure when crosslinking is applied in the dispersed phase [54]. In general, the final morphology will be the one with the lowest free Gibbs enthalpy (G s ), which can be calculated by:…”

Transparent antifouling coatings via nanoencapsulation of a biocide

“…[16][17][18] We loosely name these particles as ''core-shell'' structures, but we are aware that in fact these particles may not be core-shell at all. On the basis of the work by Sundberg et al on latex particle morphology, 19,20 we can assume that the second stage polymer is not occluded in the first stage because the first stage is crosslinked, and the second stage polymer phase is in contact with the aqueous phase. The external layer of the particle must have a low T g for the latex to be able to form a film upon drying at ambient temperature.…”