TY - JOUR
T1 - Phase behavior of athermal colloid-star polymer mixtures
AU - Mahynski, Nathan A.
AU - Panagiotopoulos, Athanassios Z.
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2013/7/14
Y1 - 2013/7/14
N2 - We investigate the depletion-induced phase behavior of athermal colloid-star polymer mixtures on a fine lattice using grand canonical Monte Carlo simulations in the "protein limit," that is, where polymer dimensions exceed those of the colloid. We consider the influence of the star's functionality, f, the macroscopic size ratio, qr = 2Rg, s/σc, where Rg, s is the radius of gyration of the star and σc is the colloid diameter, and the microscopic size ratio, d = σm/σc, where σm is the diameter of a Kuhn segment. Recent theoretical predictions concerning the qualitative interplay of qr and f in determining the phase stability of these mixtures [D. Marzi, C. N. Likos, and B. Capone, J. Chem. Phys. 137, 014902 (2012)] in the limit of large f are mostly corroborated by our results which span a much lower range of functionalities. Our results suggest a direct connection between the phase behavior and the scaling regimes of single star structure in the classical Daoud-Cotton (DC) description [M. Daoud and J. P. Cotton, J. Phys. 43, 531-538 (1982)]. Using this formalism, we define a "low" functionality limit through scaling arguments, for which our model provides a mapping of the phase behavior of colloidal mixtures with star polymers (f > 2) to linear chains (f = 2). Furthermore, our simulations suggest that as qr increases, both the critical monomer and colloid densities tend to a constant, finite value for all f; thus, we do not find the prediction by Marzi and co-workers of an upper limit to immiscibility (infinite critical densities) in terms of qr to be accurate for the stars we have investigated.
AB - We investigate the depletion-induced phase behavior of athermal colloid-star polymer mixtures on a fine lattice using grand canonical Monte Carlo simulations in the "protein limit," that is, where polymer dimensions exceed those of the colloid. We consider the influence of the star's functionality, f, the macroscopic size ratio, qr = 2Rg, s/σc, where Rg, s is the radius of gyration of the star and σc is the colloid diameter, and the microscopic size ratio, d = σm/σc, where σm is the diameter of a Kuhn segment. Recent theoretical predictions concerning the qualitative interplay of qr and f in determining the phase stability of these mixtures [D. Marzi, C. N. Likos, and B. Capone, J. Chem. Phys. 137, 014902 (2012)] in the limit of large f are mostly corroborated by our results which span a much lower range of functionalities. Our results suggest a direct connection between the phase behavior and the scaling regimes of single star structure in the classical Daoud-Cotton (DC) description [M. Daoud and J. P. Cotton, J. Phys. 43, 531-538 (1982)]. Using this formalism, we define a "low" functionality limit through scaling arguments, for which our model provides a mapping of the phase behavior of colloidal mixtures with star polymers (f > 2) to linear chains (f = 2). Furthermore, our simulations suggest that as qr increases, both the critical monomer and colloid densities tend to a constant, finite value for all f; thus, we do not find the prediction by Marzi and co-workers of an upper limit to immiscibility (infinite critical densities) in terms of qr to be accurate for the stars we have investigated.
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U2 - 10.1063/1.4811393
DO - 10.1063/1.4811393
M3 - Article
C2 - 23862965
AN - SCOPUS:84903362537
SN - 0021-9606
VL - 139
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 2
M1 - 024907
ER -