Study of the Thermal Phase Transition of Poly(N,N-diethylacrylamide-co-N-ethylacrylamide) Random Copolymers in Aqueous Solution

Autor: José Javier Coca-Hidalgo, Maricarmen Recillas-Mota, Daniel Fernández-Quiroz, Jaime Lizardi-Mendoza, Carlos Peniche-Covas, Francisco M. Goycoolea, Waldo M. Argüelles-Monal
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Polymers, Vol 16, Iss 11, p 1575 (2024)
Druh dokumentu: article
ISSN: 16111575
2073-4360
DOI: 10.3390/polym16111575
Popis: N-alkyl-substituted polyacrylamides exhibit a thermal coil-to-globule transition in aqueous solution driven by an increase in hydrophobic interactions with rising temperature. With the aim of understanding the role of N-alkyl substituents in the thermal transition, this study focuses on the molecular interactions underlying the phase transition of poly(N,N-diethylacrylamide-co-N-ethylacrylamide) random copolymers. Poly(N,N-diethylacrylamide) (PDEAm), poly(N-ethylacrylamide) (PNEAm), and their random copolymers were synthesized by free radical polymerization and their chemical structure characterized spectroscopically. It was found that the values of the cloud-point temperature increased with PNEAm content, and particle aggregation processes took place, increasing the negative charge density on their surface. The cloud-point temperature of each copolymer decreased with respect to the theoretical values calculated assuming an absence of interactions. It is attributed to the formation of intra- and interchain hydrogen bonding in aqueous solutions. These interactions favor the formation of more hydrophobic macromolecular segments, thereby promoting the cooperative nature of the transition. These results definitively reveal the dominant mechanism occurring during the phase transition in the aqueous solutions of these copolymers.
Databáze: Directory of Open Access Journals
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