Influence of excluded volume interactions on the dynamics of dendrimer and star polymers in layered random flow
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© Indian Academy of Sciences
Influence of excluded volume interactions on the dynamics of dendrimer and star polymers in layered random flow NEHA, DIVYA KATYAL and RAMA KANT
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Department of Chemistry, University of Delhi, Delhi 110 007, India ∗ Corresponding author. E-mail: [email protected] MS received 27 May 2020; accepted 30 July 2020 Abstract. The influence of excluded volume interactions (EVIs) governs the dynamics of branched polymeric structures. Therefore, we developed a theory with the inclusion of ubiquitous EVIs on average square displacement (ASD) of the centre of mass in layered random flow (LRF). The mean-field approach is used to account for effective EVIs between non-bonded monomers of generalised Gaussian structures. The effect of polymer topology is analysed under the influence of δ- and power-law correlated LRF. Qualitatively, the theory predicts two anomalous powerlaw regimes: (i) the intermediate time subdiffusive behaviour with enhanced ASD, due to EVIs, shows the internal motion of the chain and (ii) the long-time superdiffusive behaviour with slightly suppressed ASD represents the overall diffusion of the polymer. The time dependence of ASD in the presence of EVIs reveals the anomalous longtime dynamics governed by a power-law, t 2−α/2 . The model with EVIs predicts enhanced swelling of the polymeric structure and the stretching regime in the magnitude of the ASD. The influence of EVIs in star polymer causes enhanced delay in cross-over time which is further increased with increase in functionality. Dendrimer structure with EVI delays the cross-over time with spacer length. Finally, the increase in EVIs in all topologies causes the enhancement in ASD and delay in cross-over time from subdiffusive to superdiffusive regime. Keywords. Polymer dynamics; excluded volume interactions; layered random flow; generalised Gaussian structures; average squared displacement. PACS Nos 36.20.−r; 83.80.Rs; 47.57.−s
1. Introduction Polymer solutions with different branched topologies have been extensively used in various potential applications like drug delivery [1,2], catalysis [3,4], tissue engineering [5,6], biomaterials [7], etc. The dynamical behaviour of the polymers in various types of flow is strongly affected by the excluded volume interactions (EVIs) [8,9]. The swelling behaviour of the polymers in good solvents due to EVI was successfully predicted in [10,11]. In dilute solutions, the size of a real chain is determined by the diffraction experiment, its influence on the intrinsic viscosity, the osmotic second virial coefficient, the friction coefficient, etc. [12]. The physical picture underlying the bead-spring model of the polymer dynamics is that the motion of the polymer chain is strongly restricted by the surrounding of the molecules [13]. Such chains can interact strongly due to the topological constraints that the chains cannot cut through each other. In the past two decades, a subject of growing 0123456789().: V,-vol
interest about the polymer dynamics motivated by many of the pot
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