(476i) Understanding Macromolecular Transport and Desorption at Interfaces Via DPD Simulations

Polymers at interfaces are critical to various industrial applications, including membrane processes [1], reactive separations [2], emulsion stabilization [3], and liquid-liquid extraction [4]. A comprehensive understanding of the governing parameters is essential for optimizing these processes and identifying potential limitations. In this study, we employ Dissipative Particle Dynamics (DPD) simulations using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [5-8] to investigate polymer transport at liquid-liquid interfaces.

We analyze the behavior of short hydrophilic polymers positioned at the interface; computing partition coefficients based on macromolecular conformations relative to the interface. Key factors influencing polymer-interface interactions are examined, with a focus on solvent compatibility described by the Flory-Huggins parameter (χ). These interactions dictate desorption mechanisms and polymer conformational morphologies, both of which are crucial in determining partitioning behavior. Additionally, interfacial energetics influence polymer desorption, particularly in systems with a jammed nanoparticle-like structure, drawing parallels to nanoparticle detachment phenomena [9].

The impact of polymer size on desorption is also investigated, revealing size-dependent trends in partitioning. Finally, within specific parameter ranges, we establish a master curve capable of predicting partition coefficients as functions of key operational conditions. These insights contribute to a deeper understanding of polymer dynamics at interfaces and inform the design of advanced separation processes.

ACKNOWLEDGEMENTS

The support of NSF under grant EFRI-2132141 is gratefully acknowledged as the use of computing facilities at the University of Oklahoma Supercomputing Center for Education and Research (OSCER) and at XSEDE (under allocation CTS-090025).

REFERENCES

1. Cao, D. Q. et al. Membrane filtration-based recovery of extracellular polymer substances from excess sludge and analysis of their heavy metal ion adsorption properties. Chem. Eng. J. 354, 866–874 (2018).
2. Cha, S., Lim, H. G., Haase, M. F., Stebe, K. J., Jung, G. Y., Lee, D. “Bicontinuous Interfacially Jammed Emulsion Gels (bijels) as Media for Enabling Enzymatic Reactive Separation of a Highly Water Insoluble Substrate.” Scientific Reports 2019, 9 (1), 6363.
3. Kang, W. et al. Stability mechanism of W/O crude oil emulsion stabilized by polymer and surfactant. Colloids Surfaces A Physicochem. Eng. Asp. 384, 555–560 (2011).
4. Mazzola, P. G. et al. Liquid-liquid extraction of biomolecules: An overview and update of the main techniques. J. Chem. Technol. Biotechnol. 83, 143–157 (2008).
5. Groot, R.D., Warren, P.B. “Dissipative particle dynamics: Bridging the gap between atomistic and mesoscopic simulation.” The Journal of Chemical Physics 1997, 107(11), 4423-4435.
6. Plimpton, S., “Fast Parallel Algorithms for Short-Range Molecular Dynamics.” Journal of Computational Physics 1995, 117(1), 1-19.
7. Nguyen, T.X.D., Vu, T.V., Razavi, S., Papavassiliou, D.V., “Coarse Grained Modeling of Multiphase Flows with Surfactants,” Polymers 2022 14(3) Art 543 (19 pages).
8. Vu, T.V., Papavassiliou, D.V., “Synergistic effects of surfactants and heterogeneous nanoparticles at oil-water interface: Insights from computations,” Colloid & Interf. Sci. 2019, 553, 50-58.
9. Binks, B. P. Particles as surfactants-similarities and differences. Curr. Opin. Colloid Interface Sci. 7, 21–41 (2002).