Lattice Model of Equilibrium Polymerization. IV. Influence of Activation, Chemical Initiation, Chain Scission and Fusion, and Chain Stiffness on Polymerization and Phase Separation
J Dudowicz, Karl Freed, Jack F. Douglas
The influences of thermal activation, chemical initiation, chain fragmentation and chain stiffness on basic thermodynamic properties of equilibrium polymerization solutions is systematically investigated using a Flory-Huggins type lattice model. The properties treated include the average chain length L, extent of polymerization [Phi], Helmholtz free energy F, configurational entropy S, specific heat Cv, polymerization transition temperature Tp, osmotic pressure [Pi} and second and third virial coefficients A2 and A3. The dependence of the critical temperature Tc and critical composition [phi] (volume fraction of associating species) on the enthalpy [Δ]hp and entropy [Δ]sp of polymerization and on the strength [xi]FH of the FH effective monomer-solvent van der Waals interaction ([Chi] = [epsilon]FH / T is also analyzed as an illustration of the stong coupling between phase separataion and polymerization. For a given ploymerization model, both Tc and [phi]c, normailized by their values in the absence of polymerization, are functions of the dimensionless sticking energy h[epsilon] [identical to] (![Δ]hp / R) / (2[epsilon]FH) (where R is the gas constant) and [Δ]sp. Our critical comparison of free association, activated association, and chemical initiation models of equilibrium polymerization is specialized to systems that polymerize upon cooling, but the general theory also applies for polymerization on heating, essential thermodynamic properties, critical phenomena, and polymerization transitions.
, Freed, K.
and Douglas, J.
Lattice Model of Equilibrium Polymerization. IV. Influence of Activation, Chemical Initiation, Chain Scission and Fusion, and Chain Stiffness on Polymerization and Phase Separation, Journal of Chemical Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852246
(Accessed June 7, 2023)