Static and dynamic scaling behavior of a polymer melt model with triple‐well bending potential

Abstract

We perform molecular-dynamics simulations for polymer melts of the coarse-grained poly(vinyl alcohol) model that crystallizes upon slow cooling. To establish the properties of its high temperature, liquid state as a reference point, we characterize in detail the structural features of equilibrated polymer melts with chain lengths 5 ≤ N ≤ 1000 at a temperature slightly above their crystallization temperature. We find that the conformations of sufficiently long polymers with N > 50 obey essentially the Flory's ideality hypothesis. The chain length dependence of the end-to-end distance and the gyration radius follow the scaling predictions of ideal chains and the probability distributions of the end-to-end distance, and form factors are in good agreement with those of ideal chains. The intrachain correlations reveal evidences for incomplete screening of selfinteractions. However, the observed deviations are small. Our results rule out any preordering or mesophase structure formation that are proposed as precursors of polymer crystallization in the melt. Moreover, we characterize in detail primitive paths of long entangled polymer melts and we examine scaling predictions of Rouse and the reptation theory for the mean squared displacement of monomers and polymers center of mass.

Crystallization of Polymers under the Influence of an External Force Field

“…The data follow a linear function suggesting that polymer chains do not deviate from Gaussian behavior in the range of forces applied in this work. The value of the Kuhn length, Å, obtained from the force extension curve is in good agreement with the previous calculations [ 38 ].…”

Modeling of Entangled Polymer Diffusion in Melts and Nanocomposites: A Review

“…That mapping procedure between the PS CG model and the KG model enabled measurement of polymer dynamics up to the subsecond time scale [77]. Furthermore, a coarse-grained poly(vinyl alcohol) (PVA) model with a triple-well bending potential has been developed to predict polymer dynamics, structure and crystallization during cooling [105]. However, it is an open question if such developed CG models are applicable at other temperatures.…”

The Swelling of Poly(Isopropylacrylamide) Near the θ Temperature: A Comparison between Linear and Cross‐Linked Chains

“…Results by Zryny et al for poly(vinyl alcohol) in isopropanol near the theta temperature give φ(T = θ)/φ(T = θ + 5) ≃ 1.1 for a cross-linking density of f ≃ 0.02 (N ≃ 20, N K ≃ 2-9 [102][103][104] ). We lack data to compare this result with the swelling of an equivalent linear chain, but approximating b ≈ 0.25 nm, d ≈ 1 nm, L K ≈ 0.6 nm, and τ = 0.015, we estimate g T ≈ 4 × 10 3 and ξ T ≈ 24 nm; a chain with N ≈ 20 ≪ g T is not expected to display significant swelling with respect to the theta dimensions.…”