A coarse-grained model for aqueous two-phase systems: Application to ferrofluids
: Scacchi, Alberto; Rigoni, Carlo; Haataja, Mikko; Timonen, Jaakko V. I.; Sammalkorpi, Maria
Publisher: Elsevier Inc.
: SAN DIEGO
: 2025
: Journal of Colloid and Interface Science
: Journal of Colloid and Interface Science
: J COLLOID INTERF SCI
: 686
: 1135
: 1146
: 12
: 0021-9797
: 1095-7103
DOI: https://doi.org/10.1016/j.jcis.2025.01.256(external)
: https://doi.org/10.1016/j.jcis.2025.01.256(external)
: https://research.utu.fi/converis/portal/detail/Publication/491218127(external)
Aqueous two-phase systems (ATPSs), phase-separating solutions of water soluble but mutually immiscible molecular species, offer fascinating prospects for selective partitioning, purification, and extraction. Here, we formulate a general Brownian dynamics based coarse-grained simulation model for an ATPS of two water soluble but mutually immiscible polymer species. Including additional solute species into the model is straightforward, which enables capturing the assembly and partitioning response of, e.g., nanoparticles (NPs), additional macromolecular species, or impurities in the ATPS. We demonstrate that the simulation model captures satisfactorily the phase separation, partitioning, and interfacial properties of an actual ATPS using a model ATPS in which a polymer mixture of dextran and polyethylene glycol (PEG) phase separates, and magnetic NPs selectively partition into one of the two polymeric phases. Phase separation and NP partitioning are characterized both via the computational model and experimentally, under different conditions. The simulation model captures the trends observed in the experimental system and quantitatively links the partitioning behavior to the component species interactions. Finally, the simulation model reveals that the ATPS interface fluctuations in systems with magnetic NPs as a partitioned species can be controlled by the magnetic field at length scales much smaller than those probed experimentally to date.
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This work was supported by the Swiss National Science Foundation under the project no. P500PT_206916 (A.S.) and the Academy of Finland through its Centres of Excellence Programs (2022-2029, LIBER) under projects no. 346111 and 364205 (M.S.) and 346112 and 364206 (J.T.). MPH was supported by the National Science Foundation through the Princeton University (PCCM) Materials Research Science and Engineering Center DMR-2011750. A.S. warmly thanks Bob Evans for extensive scientific discussions and for his hospitality during the research visit in Bristol. Computational resources by CSC IT Centre for Finland, the Aalto Science-IT project, and RAMI – RawMatters Finland Infrastructure are also gratefully acknowledged.
