The Waterborne Symposium 2025

Co-Author(s):
Nicholas Foley, Cheng-Le Zhao, Mohsen Soleimani, Mitchell A. Winnik, Yang Liu, Sze Hang Wong, Ilias Halimi, Richard Fuku, John Hou, Gilbert Walker

Abstract
In the coatings industry, additives play a significant role in achieving the desired properties of coatings. One class of additives, acid-rich oligomers, improve properties of coatings, such as hardness, block resistance, and stain resistance. However, the distribution and influence of these acid rich oligomers on film formation are not well understood. In this research, we study the distribution of an acid-rich oligomer in latex films and its influence on film formation. We utilize Förster resonance energy transfer (FRET), confocal laser scanning microscopy (CLSM), and atomic force microscopy (AFM) to investigate the film formation process. The distribution of acid-rich oligomer depends on the particle size of the latex dispersion, the degree of neutralization of the acid-rich oligomer dispersion, and the amount of acid-rich oligomer in the blend. CLSM and AFM reveal that the acid-rich oligomer, under specific conditions, phase separates and concentrates at the surface of the film. At the surface of the film, acid-rich oligomer acts as mortar between latex particles, resulting in a higher average Young's modulus. FRET reveals that the acid-rich oligomer present in the interstices of the latex particles retard latex particles interdiffusion and film formation. Thus, a combination of analytical techniques elucidates the distribution of acid rich oligomer in the polymer film.