2020/11/29 by Khederlarian, Ashod, Carmen Almasri, Almasri, Carmen +2
Chemistry · Engineering · Materials Science · Physics and Astronomy · #Advanced Physical and Chemical Molecular Interactions #Advanced Thermodynamics and Statistical Mechanics #FOS: Physical sciences #Material Dynamics and Properties #Phase Equilibria and Thermodynamics #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2011.14438
openalex publication_date 2020/11/29 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
We explore semi-dilute and concentrated oligomers and polymers in a broad\nrange of polymerization indices N ranging from 1 to a 100 and in a range of\nmonomer number densities \φ from 0.1 to 0.8 via molecular dynamics\nsimulations and under good solvent conditions. This parameter range covers both\nno-overlap and strong chain overlap regimes, as quantified by the polymer\npacking fraction 0.1\≤\Φ\≤14. Contrary to some common beliefs, the\nnon-ideal part of the osmotic pressure demonstrates strong finite size effects.\nIn the overlap regime, it deviates substantially from the scaling form of de\nCloizeaux. The finite size correction term is proportional to 1/N, irrespective\nof \Φ. We propose a simple phenomenological description of the osmotic\npressure in the infinite chain limit and of the monomer density dependence of\nthe 1/N correction term. We extend the treatment of finite size effects to\ncover binary mixtures with 2 different chain lengths, and demonstrate that the\nproposed equation of state is applicable with an effective mass-averaged\ninverse chain length 1/Neff. We also discuss finite size effects in the\ndensity dependence of the gyration radius.\n