Lattice Model of Living Polymerization. III. Evidence for Particle Clustering From Phase Separation Properties and Rounding of the Dynamical Clustering Transition

Published

July 1, 2000

Author(s)

J Dudowicz, Karl Freed, Jack F. Douglas

Abstract

Equilibrium polymerization is studied here as a prototype for clustering transitions that commonly occur in systems of interacting particles at equilibrium. These transitions are often difficult to locate because of transition rounding associated with a limited extent of cluster growth, competing association and dissociation processes that initiate or inhibit clustering and other constraints on the clustering dynamics. Instead of singularities in thermodynamic and transport properties, more subtle property changes signal the onset of particle clustering, explaining why clustering transitions are often overlooked or misinterpreted. We utilize a Flory-Huggins model to describe the equilibrium (living) polymerization of linear polymer chains to identify experimental signatures (features in the osmotic pressure, osmotic compressibilty, and specific heat) that can be used to locate and quantify the transition rounding in general clustering transitions. The computation of a flattening in the concentratrion dependence of the osmotic pressure in the one-phase region motivates our consideration of the temperature dependence of the second virial coefficient and the variation of the theta temperature with sticking energy as possible indicators of particle clustering. The ratio of the critical temperature for phase separation to the theta temperature, along with other critical constant ratios, such as the critical compressibilty factor are calculated and discussed in connection with establishing criteria for identifying particle clustering transitions and for quantifying the relative stength of these transitions.

Citation

Journal of Chemical Physics

Volume

113

Issue

No. 1

Pub Type

Journals

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Keywords

lattice model, living polymerization, particle clustering, phase separation, second virial coefficient, specific heat

Citation

Dudowicz, J. , Freed, K. and Douglas, J. (2000), Lattice Model of Living Polymerization. III. Evidence for Particle Clustering From Phase Separation Properties and Rounding of the Dynamical Clustering Transition, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852807 (Accessed April 26, 2024)