Lattice Model of Living Polymerization I. Basic Thermodynamic Properties

Published

October 1, 1999

Author(s)

J Dudowicz, Karl Freed, Jack F. Douglas

Abstract

A Flory-Huggins type model of living polymerization is formulated, incorporating chain stiffness, variable initiator concentration and polymer-polymer interactions. Basic equilibrium properties [average chain length L, average fraction of associated monomers diameter}, specific heat Cp, entropy S, and the chain length distribution p(N)] are calculated within mean-field theory. Our illustrative calculations are restricted to systems that polymerize upon cooling [e.g., poly(α-methylstyrene)], but the formalism also applies to polymerization upon heating (e.g., sulfur, actin). Emphasis is given to living solutions having a finite initiator concentration r in order to compare theory with recent experiments by Greer and coworkers, whereas previous primary focus on the r-> 0⁺ limit where the polymerization transition has been described as a second order phase transition. The general phenomena are analyzed in terms of three characteristic temperatures: a crossover temperature demarking the onset of polymerization, a polymerization temperature where Cp has a maximum, and a saturation temperature at which the extent of polymerization is almost complete. Paper 2 considers the interplay between polymerization and phase separation in living polymer solutions. Many of the properties of living polymers are representative of self-assembling systems (thermally reversible polymer gels, colloidal gels, micelles), and comparisons with other self-assembling systems are briefly indicated.

Citation

Journal of Chemical Physics

Volume

111

Issue

No.15

Pub Type

Journals

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Keywords

associating polymer, gelation, glasses, living polymers, micelles

Citation

Dudowicz, J. , Freed, K. and Douglas, J. (1999), Lattice Model of Living Polymerization I. Basic Thermodynamic Properties, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851616 (Accessed December 12, 2024)