Effect of small molecules on the phase behavior and coacervation of aqueous solutions of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrene sulfonate)

Shuyue Huang; Mengmeng Zhao; Mahesh B Dawadi; Yuhang Cai; Yakov Lapitsky; David A Modarelli; Nicole S Zacharia

doi:10.1016/j.jcis.2018.02.029

Effect of small molecules on the phase behavior and coacervation of aqueous solutions of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrene sulfonate)

J Colloid Interface Sci. 2018 May 15:518:216-224. doi: 10.1016/j.jcis.2018.02.029. Epub 2018 Feb 9.

Authors

Shuyue Huang¹, Mengmeng Zhao¹, Mahesh B Dawadi², Yuhang Cai³, Yakov Lapitsky³, David A Modarelli², Nicole S Zacharia⁴

Affiliations

¹ Department of Polymer Engineering, University of Akron, Akron, OH 44325, United States.
² Department of Chemistry, University of Akron, Akron, OH 44325, United States.
³ Department of Chemical Engineering, University of Toledo, Toledo, OH, 43606, United States.
⁴ Department of Polymer Engineering, University of Akron, Akron, OH 44325, United States. Electronic address: nzacharia@uakron.edu.

PMID: 29459301
DOI: 10.1016/j.jcis.2018.02.029

Abstract

Hypothesis: Complex coacervates are capable of easily partitioning solutes within them based on relative affinities of solute-water and solute-polyelectrolyte pairs, as the coacervate phase has low surface tension with water, facilitating the transport of small molecules into the coacervate phase. The uptake of small molecules is expected to influence the physicochemical properties of the complex coacervate, including the hydrophobicity within coacervate droplets, phase boundaries of coacervation and precipitation, solute uptake capacity, as well as the coacervate rheological properties.

Experiments: Phase behavior of aqueous solutions of poly(diallyldimethylammonium chloride) (PDAC) and poly(sodium 4-styrene sulfonate) (SPS) was investigated in the presence of various concentrations of two different dyes, positively charged methylene blue (MB) or non-charged bromothymol blue (BtB), using turbidity measurements. These materials were characterized with UV-vis spectroscopy, zeta potential measurements, isothermal titration calorimetry (ITC), fluorescence spectroscopy, and dynamic rheological measurements.

Findings: The presence of MB or BtB accelerates the coacervation process due to the increased hydrophobicity within coacervates by the addition of MB or BtB. The encapsulated MB or BtB tends to reduce the ionic crosslink density in the PDAC-SPS coacervates, resulting in a much weaker interconnecting network of the PDAC-SPS coacervates.

Keywords: Electrostatic; Encapsulation; Hydrophobic interaction; Polyelectrolyte coacervation; Separations.