Computer simulation of end-linked elastomers. II. Bulk cured tetrafunctional networks

Abstract

Weak-to-strong confinement transition of semi-flexible macromolecules in slit and in channel J. Chem. Phys. 136, 024902 (2012) Communication: Quantum polarized fluctuating charge model: A practical method to include ligand polarizability in biomolecular simulations J. Chem. Phys. 135, 231101 (2011) Proton-driven spin diffusion in rotating solids via reversible and irreversible quantum dynamics JCP: BioChem. Phys. 5, 10B606 (2011) Proton-driven spin diffusion in rotating solids via reversible and irreversible quantum dynamics J. Chem. Phys. 135, 134509 (2011) Spectroscopy and thermochemistry of a jet-cooled open-shell polyene: 1,4-pentadienyl radical J. Chem. Phys. 135, 124306 (2011) Additional information on J. Chem. Phys. Sol-gel distributions at high conversions, simulated by computer with spatial constraints on the distribution of chain ends, are reported for end-linked tetrafunctional systems. The composition of the sol is found to be uniquely dependent upon the functionality f of the cross linker: for f = 4, it mainly consists of linear monomers and oligomers containing one saturated cross linker. The molecular weight distribution of the sol exhibits a shoulder at the trimer due to the relative abundance of the "bow-tie" molecule. The populations of various types of dangling ends and loop defects in the gel are given and discussed. Our simulations reveal empirically that the single-loop probability varies with the -3/8 power of the molecular weight of the prepolymers. The powerlaw dependence of the loop formation on chain length of the prepolymers and the nonrandom nature of the cross-linking reaction is discussed.

Moduli of Elastomeric Networks Prepared by Tetrafunctionally Endlinking Vinyl-Terminated Poly(dimethylsiloxane) Chains at Low Temperature

“…Computer simulation experiments provide further support to this assumption. 36 Consequently, reported values of the extent of reaction thus obtained are suspect.…”

Random Networks, Graphs, and Matrices

“…Putting Equation (19) together with Equation (6) and Equation (18), gives the free energy of the elastomer (as characterized by the constraint C), as…”

“…Computer modeling of network formation [17,18] with evaluation of the eigenvalue spectrum of the KL matrix [19] has thus far offered the best insights into this problem. The particularly delicate problem of evaluating k 1 for large networks is critical, since on the face of it there is a problem with the modulus in Equation (22).…”

Polymer Networks: A Challenge to Theorist and Technologist

“…Problems will be encountered with selection of reaction partners if they are not spatial neighbors. Off-lattice simulations are more sophisticated [18]: the reactants are dispersed in space and Cartesian coordinates are assigned to each of them or to their centers of gravity. If the reactants are oligomers with their own distribution of conformations, this component can be placed in space in different conformational states.…”