Atomic Force Microscopy Study

• Published in: Paint & Coatings Industry Vol. 33; no. 6; p. 30
• Main Authors: Santos, Juliane Pereira, Pagani, Robson André, Tomassini, Carlos Roberto, da Silva, Rafael Caetano Jardim Pinto, Barrios, Silmar Balsamo, Sharp, Kip
• Format: Trade Publication Article
• Language: English
• Published: Troy BNP Media 01-06-2017
• Subjects: Atomic force microscopy; Atoms & subatomic particles; Glass substrates; Microscopy; Morphology; Outdoor air quality; Paints; Particle size; Polymers; Protective coatings; Temperature; Topography; VOCs; Volatile organic compounds
• ISSN: 0884-3848; 2328-8329

Effect of Low-VOC Coalescents on Morphology and Phase Distribution of Latex Films Today, growing concerns about the negative impact of volatile organic compounds (VOCs) on the environment have motivated the development of stricter regulations that control the VOC content of coatings. Due to this, coalescents with higher molecular weights and boiling points have been developed in order to comply with these regulations and help paint formulators to develop low-VOC paints. Atomic force microscopy (AFM) is a consolidate technique for evaluating the morphological aspects of latex films2,3 as well as the effects of drying conditions and coalescent content on latex film formation.4 In this work, latex films containing three low-VOC coalescents, based on Method 313 of SCAQMD (South Coast Air Quality Management District), were evaluated through AFM, and their impact on film morphology and phase distribution within the films was compared to the impact of a standard high-VOC coalescent. Both latexes have typical solid content, particle sizes ranging from 200 to 300 nm, and MFFT lower than their Tg, probably due to the presence of hydrophilic groups within the latex particles that help their hydroplasticization.3-5 Coalescent A is a commercial high-VOC coalescent with high plasticization power and low solubility in water used as reference in this study. Figures 1a and 1b present the estimated coalescent concentration required to form film at 0 °C of vinyl-acrylic latex, MFFT of 12 °C, and acrylic latex, MFFT of 20 °C. The estimated concentrations of low-VOC coalescents required to form film at 0 °C were...