Determination of θ-conditions for the parameterization of the intrachain stiffness of a linear polymer chain in the dissipative particle dynamic method

To construct mesoscale models of molecular systems, the structure of all chemical components is simplified through a transformation known as «coarsening». In the case of modeling polymer materials, the conformational properties of roughened polymer chain models may not correspond to the original chemical prototypes. This can be compensated by introducing additional potentials into the model. Conditions for a model of a linear polymer chain with «beads and springs» in the infinitely diluted solution are determined using the dissipative particle dynamic method. It has been shown that the maximum amplitude value of the conservative force, that determines the interaction between the polymer and the solvent corresponding to these conditions, strongly depends on the stiffness constant Kb of the bond deformation potential. When Kb is greater than 30, this value tends to saturate. For Kb = 200, a relationship between the characteristic ratio of model chain lengths and the stiffness constant Ka was calculated. The results obtained are in good agreement with literature data and can be reproduced using theoretical calculations. The functional relationship between C∞ and Ka is universal and can be applied to construct accurate models of various polymers when their conformational characteristics are important.