Single-Chain Nanoparticles under Homogeneous Shear Flow

Abstract

Single-chain nanoparticles (SCNPs) are ultrasoft objects obtained through purely intramolecular cross-linking of single polymer chains. By means of computer simulations with implemented hydrodynamic interactions, we investigate for the first time the effect of the shear flow on the structural and dynamic properties of SCNPs in semidilute solutions. We characterize the dependence of several conformational and dynamic observables on the shear rate and the concentration, obtaining a set of power-law scaling laws. The concentration has a very different effect on the shear rate dependence of the former observables in SCNPs than in simple linear chains. Whereas for the latter the scaling behavior is marginally dependent on the concentration, two clearly different scaling regimes are found for the SCNPs below and above the overlap concentration.At fixed shear rate SCNPs and linear chains also respond very differently to crowding.Whereas, at moderate and high Weissenberg numbers the linear chains swell, the SC-NPs exhibit a complex non-monotonic behavior. These findings are inherently related to the topological interactions preventing concatenation of the SCNP loops, leading to less interpenetration than for linear chains.

Hydrodynamic inflation of ring polymers under shear

“…Recently, the sedimentation behavior of flexible, non-Brownian knots has been added to the host of counterintuitive phenomena [65] . All polymer architectures (linear, star, dendritic, crosslinked and ring) are known to undergo tumbling under steady shear at sufficiently high shear rates [26,[66][67][68][69][70][71][72][73] . Moreover, it is known that linear chains never fully stretch under shear and they reach a stretched configuration only under so-called planar mixed flows that represent a combination of simple shear and planar extension [27,74,75] .…”

Mesoscale modelling of polymer aggregate digestion

“…Mattice and Suter [32] and Liebetreu et al [33]. In particular, gyration tensors have been defined for individual ring polymers [33,34] and single-chain polymeric nanoparticles [35]. The bolus gyration radius is related to the trace of the gyration tensor G k as…”

“…We choose the offset time t 0 = t sim /20 so that the repulsion-dominated initial period during which the bolus gyration radius goes through a maximum does not contribute to the correlation functions. Negative peaks in the cross-correlation function C xz are a hallmark of tumbling motion [35]. These peaks arise because the polymer chains are preferentially stretched along the flow direction, but thermal fluctuations cause stretching in the gradient direction.…”

Controlled self-aggregation of polymer-based nanoparticles employing shear flow and magnetic fields

“…For sufficiently large shear rates (γ 10 −2 in inverse MPCD time units), the orientational resistance follows a power-law m G ∝γ µ with a characteristic exponent 0.4 < µ < 0.6. This behavior is shared by the majority of polymeric systems (each with a corresponding value of µ), ranging from linear chains to block copolymers, randomly cross-linked singlechain nanoparticles, dendrimers, and non-magnetic star polymers [6,19,20,21,22]. Thus, while the exponent µ varies with B, the characteristic power-law of star polymers is conserved despite the addition of a magnetic interaction and the associated introduction of another distinguished axis.…”