Maximally stiffening composites require maximally coupled rather than maximally entangled polymer species

Abstract

Polymer composites are ideal candidates for next generation biomimetic soft materials because of their exquisite bottom-up designability. However, the richness of behaviours comes at a price: the need for precise and extensive characterisation of material properties over a highly-dimensional parameter space, as well as a quantitative understanding of the physical principles underlying desirable features. Here we couple large-scale Molecular Dynamics simulations with optical tweezers microrheology to characterise the viscoelastic response of DNA-actin composites. We discover that the previously observed non-monotonic stress-stiffening of these composites is robust, yet tunable, in a broad range of the parameter space that spans two orders of magnitude in DNA length. Importantly, we discover that the most pronounced stiffening is achieved when the species are maximally coupled, i.e. have similar number of entanglements, and not when the number of entanglements per DNA chain is largest. We further report novel dynamical oscillations of the microstructure of the composites, alternating between mixed and bundled phases, opening the door to future investigations. The generic nature of our system renders our results applicable to the behaviour of a broad class of polymer composites. arXiv:1907.12164v1 [cond-mat.soft]

Dynamical Entanglement and Cooperative Dynamics in Entangled Solutions of Ring and Linear Polymers

“…Finally, we highlight that our DEA can be applied to any polymeric system, and we envisage interesting outcomes on entangled blends, composites, , or chimeric polymer systems.…”

Dynamical Entanglement and Cooperative Dynamics in Entangled Solutions of Ring and Linear Polymers

“…Finally, we highlight that our DEA can be applied to any polymeric system and we envisage interesting outcomes on entangled blends [16], composites [47,48] or chimeric [17] polymer systems.…”

Topological Tuning of DNA Mobility in Entangled Solutions of Supercoiled Plasmids

“…In fact, DNA is at present largely employed in its simplest geometrical form, i.e. that of a linear or nicked circular (torsionally unconstrained) molecule [8][9][10][11][12]. In spite of this, most of the naturally occurring DNA is under torsional and topological constraints, either because circular and non-nicked (as in bacteria) or because of the binding of proteins that restrict the relative rotation of base-pairs in eukaryotes [13][14][15][16].…”