2018/10/15 by Ian Seim, Seim, Ian, Jeremy Cribb +11
Agricultural and Biological Sciences · Chemical Engineering · Medicine · #Blood properties and coagulation #FOS: Physical sciences #Polysaccharides Composition and Applications #Rheology and Fluid Dynamics Studies #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.1810.06649
openalex publication_date 2018/10/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We report observations of a remarkable scaling behavior with respect to concentration in the passive microbead rheology of two highly entangled polymeric solutions, polyethylene oxide (PEO) and hyaluronic acid (HA). This behavior was reported previously [Hill et al., PLOS ONE (2014)] for human lung mucus, a complex biological hydrogel, motivating the current study for synthetic polymeric solutions PEO and HA. The strategy is to identify, and focus within, a wide range of lag times τ for which passive micron diameter beads exhibit self-similar (fractional, power law) mean-squared-displacement (MSD) statistics. For lung mucus, PEO at three different molecular weights (Mw), and HA at one Mw, we find ensemble-averaged MSDs of the form ⟨Δr2(τ)⟩ = 4Dατα, all within a common band, [1/60 sec, 3 sec], of lag times τ. We employ the MSD power law parameters (Dα,α) to classify each polymeric solution over a range of highly entangled concentrations. By the generalized Stokes-Einstein relation, power law MSD implies power law elastic G'(ω) and viscous G''(ω) moduli for frequencies 1/τ, [0.33 sec-1, 60 sec-1]. A natural question surrounds the polymeric properties that dictate Dα and α, e.g. polymer concentration c, Mw, and stiffness (persistence length). In [Hill et al., PLOS ONE (2014)], we showed the MSD exponent α varies linearly, while the pre-factor Dα varies exponentially, with concentration, i.e. the semi-log plot, (log(Dα),α)(c) of the classifier data is collinear. Here we show the same result for three distinct Mw PEO and HA at a single Mw. Future studies are required to explore the generality of these results for polymeric solutions, and to understand this scaling behavior with polymer concentration.