Menichetti R, Pelissetto A, Randisi F. Thermodynamics of star polymer solutions: A coarse-grained study.
J Chem Phys 2018;
146:244908. [PMID:
28668065 DOI:
10.1063/1.4989476]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We consider a coarse-grained (CG) model with pairwise interactions, suitable to describe low-density solutions of star-branched polymers of functionality f. Each macromolecule is represented by a CG molecule with (f + 1) interaction sites, which captures the star topology. Potentials are obtained by requiring the CG model to reproduce a set of distribution functions computed in the microscopic model in the zero-density limit. Explicit results are given for f = 6, 12, and 40. We use the CG model to compute the osmotic equation of state of the solution for concentrations c such that Φp=c∕c*≲1, where c* is the overlap concentration. We also investigate in detail the phase diagram for f = 40, identifying the boundaries of the solid intermediate phase. Finally, we investigate how the polymer size changes with c. For Φp≲0.3, polymers become harder as f increases at fixed reduced concentration c∕c*. On the other hand, for Φp≳0.3, polymers show the opposite behavior: At fixed Φp, the larger the value of f, the larger their size reduction is.
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