From Associative to Segregative Phase Separation: The Phase Behavior of Poly(acrylate)/Dodecyltrimethylammonium Complex Salts in the Presence of NaBr and NaCl

Author(s)

Aquino Queiros, Marcos Vinicius ^[1] ; Loh, Watson ^[1]

Affiliation

^[1] Univ Estadual Campinas, UNICAMP, Inst Chem, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: Journal of Physical Chemistry B; v. 125, n. 11, p. 2968-2975, MAR 25 2021.
• Web of Science Citations: 0

Abstract

We report here a systematic study on the phase behavior of dodecyltrimethylammonium-poly(acrylate) (C12TAPA) complex salts upon addition of simple salts (NaBr and NaCl). Complex salts of poly(acrylate) of two molar masses were employed (2000 and 450,000 g mol(-1)). Systems containing different surfactant mesophases were observed, whose structures were elucidated by small-angle X-ray scattering analyses. Overall, we observe a transition from associative to segregative phase separation intercalated with monophasic regions. In terms of surfactant association, a transition from micellar cubic phases to an isotropic micellar solution was observed, where these two phases occur in equilibrium with a dilute phase as a consequence of associative phase separation. However, as the salt concentration increases, segregative phase separation is observed, and scattering analyses of the surfactant-rich phase indicate the growth of micellar aggregates. These results are discussed in terms of the electrolyte effect screening the interactions between the oppositely charged surfactant and polymer and as a result of salting-out effects of the different electrolytes that prevail at higher concentrations. (AU)

• FAPESP's process: 18/09099-3 - Phase behavior of electrostatic complexes in systems containing polymers and surfactants in the presence of inorganic salts
• Grantee: Marcos Vinícius Aquino Queirós
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/25406-5 - Organizing matter: colloids formed by association of surfactants, polymers and nanoparticles
• Grantee: Watson Loh
• Support Opportunities: Research Projects - Thematic Grants