abstract
The understanding of molecular interactions that control phase separation in polymer/polymer aqueous two-phase systems (ATPS) has been a subject of debate up to this day. In light of this, we set out to investigate the molecular interactions occurring in ternary mixtures composed of polyethylene glycol (PEG600), polypropylene glycol (PPG400) and water. The ternary phase diagram was plotted at two temperatures (298 K and 323 K), revealing a transition from a type 0 to a type I diagram. Molecular dynamics (MD) simulations were performed to elucidate the polymer-polymer and polymer-water interactions occurring at different temperatures and water concentrations. COnductor-like Screening Model for Realistic Solvents (COSMO-RS) was used to assess the thermodynamic properties of the polymer-water binary mixtures and their correlation with ATPS formation. The MD simulations clearly demonstrate the effect of segregation/separation with increasing water content and temperature, highlighting a significant reduction in PPG-water interactions compared to PEG-water counterparts. Polymer-water interactions were identified as those controlling the phase separation mechanism, and the thermodynamic properties determined with COSMO-RS for the polymer-water binary systems further support this view. Experimental data and MD simulations of PEG/PPG/H2O ternary mixtures at different temperatures and water contents allow the understanding of the molecular interactions governing phase separation in this polymer/polymer ATPS.
keywords
POLY(ETHYLENE OXIDE); POLYETHYLENE-GLYCOL; PROTEIN SEPARATION; PHASE-SEPARATION; DYNAMICS; WATER; APPROXIMATION; MIXTURES; ENERGY
subject category
Chemistry; Physics
authors
Jorge, AMS; Silva, GMC; Coutinho, JAP; Pereira, JFB
our authors
Gonçalo Miguel Carvalho da Silva
Junior Researcher
Jorge Fernando Brandão Pereira
PhD StudentProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
This work was partly developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI: 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI: 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI: 10.54499/LA/P/0006/2020), financed by National funds through the FCT/MCTES (PIDDAC). CIEPQPF is supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the projects UIDB/EQU/00102/2020 and UIDP/EQU/00102/2020. J. F. B. Pereira and A. M. S. Jorge acknowledge FCT for funding the project DRI/India/0044/2020 (https://doi.org/10.54499/DRI/India/0044/2020).