The counterion-mediated controllable coacervation of nano-ions with polyelectrolytes

Binghui Xue; Yuyan Lai; Yuan Liu; Mu Li; Xinpei Li; Panchao Yin

doi:10.1016/j.jcis.2023.03.105

The counterion-mediated controllable coacervation of nano-ions with polyelectrolytes

J Colloid Interface Sci. 2023 Jul:641:853-860. doi: 10.1016/j.jcis.2023.03.105. Epub 2023 Mar 20.

Authors

Binghui Xue¹, Yuyan Lai¹, Yuan Liu¹, Mu Li¹, Xinpei Li¹, Panchao Yin²

Affiliations

¹ State Key Laboratory of Luminescent Materials and Devices & South China Advanced Institute for Soft Matter Science and Technology, South China University of Technology, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology, Dongguan 523803, China.
² State Key Laboratory of Luminescent Materials and Devices & South China Advanced Institute for Soft Matter Science and Technology, South China University of Technology, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology, Dongguan 523803, China. Electronic address: yinpc@scut.edu.cn.

PMID: 36966574
DOI: 10.1016/j.jcis.2023.03.105

Abstract

Nano-ions can complex with polyelectrolytes for coacervates with hierarchical structures; however, the rational design of functional coacervations is still rare due to the poor understanding of their structure-property relationship from their complex interaction. Herein, 1 nm anionic metal oxide clusters, PW₁₂O₄₀^3-, with well-defined, mono-disperse structures are applied to complex with cationic polyelectrolyte and the system shows tunable coacervation via the alternation of counterions (H⁺ and Na⁺) of PW₁₂O₄₀^3-. Suggested from Fourier transform infrared spectroscopy (FT-IR) and isothermal titration studies, the interaction between PW₁₂O₄₀^3- and cationic polyelectrolytes can be modulated by the bridging effect of counterions via hydrogen bonding or ion-dipole interaction to carbonyl groups of polyelectrolytes. The condensed structures of the complexed coacervates are explored by small angle X-ray and neutron scattering techniques, respectively. The coacervate with H⁺ as counterions shows both crystallized and discrete PW₁₂O₄₀^3- clusters, with a loose polymer-cluster network in comparison to the system of Na⁺ which shows a dense packing structure with aggregated nano-ions filling the meshes of polyelectrolyte networks. The bridging effect of counterions helps understand the super-chaotropic effect observed in nano-ion system and provides avenues for the design of metal oxide cluster-based functional coacervates.

Keywords: Coacervate; Counterion; Nano-ion; Small angle scattering; Super-chaotropic effect.