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 cc. 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.
Thermodynamics of star polymer solutions: A coarse-grained study / Menichetti, R.; Pelissetto, A.; Randisi, F.. - In: THE JOURNAL OF CHEMICAL PHYSICS. - ISSN 0021-9606. - 146:24(2017), p. 244908. [10.1063/1.4989476]
Thermodynamics of star polymer solutions: A coarse-grained study
Menichetti R.;
2017-01-01
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 cc. 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione