Tuning Adsorption Duration To Control the Diffusion of a Nanoparticle in Adsorbing Polymers

Abstract

Controlling the nanoparticle (NP) diffusion in polymers is a prerequisite to obtain polymer nanocomposites (PNCs) with desired dynamical and rheological properties and to achieve targeted delivery of nanomedicine in biological systems. Here we determine the suppression mechanism of direct NP-polymer attraction to hamper the NP mobility in adsorbing polymers and then quantify the dependence of the effective viscosity η felt by the NP on the adsorption duration τ of polymers on the NP using scaling theory analysis and molecular dynamics simulations. We propose and confirm that participation of adsorbed chains in the NP motion break up at time intervals beyond τ due to the rearrangement of polymer segments at the NP surface, which accounts for the onset of Fickian NP diffusion on a time scale of t ≈ τ. We develop a power law, η ∼ (τ), where ν is the scaling exponent of the dependence of polymer coil size on the chain length, which leads to a theoretical basis for the design of PNCs and nanomedicine with desired applications through tuning the polymer adsorption duration.

Nanoparticle Mobility within Permanently Cross-Linked Polymer Networks

“…The g np ( r ) is essentially independent of N x , which is consistent with the behavior in dense polymer melts . The autocorrelation of monomers distributed inside the adsorption layer surrounding a NP , was calculated to describe the dynamical relaxation of polymer adsorption, where N P ads is the number of monomers inside the adsorption layer and ID(0) and ID­( t ) are the adsorbed monomer IDs at the times 0 and t , respectively. The adsorption layer is defined as the polymer segments adsorbed around a NP within a cutoff distance of r ≈ 3.0σ (the location of the first minimum of g np ( r )).…”

“…In many polymer nanocomposites, including filled elastomers, NP–polymer attraction is often introduced to improve the NP dispersion. − When the NP–polymer attraction is weak that only the depletion of polymer chains on NP surface can be released, the terminal NP diffusion is still decided by the relaxation mode of polymer subsections with size equal to d NP . , Increasing the NP–polymer attraction would suppress the NP diffusivity. ,− A very recent theoretical work by Yamamoto et al , has proposed two competing mechanisms called core–shell and vehicle diffusion to address this problem. In the core–shell mechanism, NPs and the adsorbed polymer chains diffuse together with an effective size larger than d NP , similar to that of polymer-grafted NPs. − This mechanism is particularly available for the case where the matrix chains are short and the NP–polymer attraction is so strong that the adsorbed chains cannot relax prior to the Fickian NP diffusion, while in the other case, i.e., the desorption time of polymers is shorter than their complete Rouse or reptation time, vehicle mechanism works, where the adsorbed NPs use polymer chains as carriers or “vehicles”.…”

Physics of the nuclear pore complex: Theory, modeling and experiment

“…Further complicating things, the diffusion coefficient -which is treated as a phenomenological constant in this simple description -in general depends on the FG nup density, structure and the interaction strength. How interacting particles diffuse within the interior of such a complex polymeric material still remains an open problem [52,[254][255][256][257][258][259][260][261][262][263][264][265][266][267].…”

“…As mentioned in Section 4.1.1, description of the motion of an interacting particle through a polymer assembly on the nanoscale is a non-trivial problem [51,52,254,[260][261][262]264,272,273]. However, as a first approximation, such transport can be thought of as diffusion in an effective free energy potential.…”

Adding Nonconnected Monomers to Manage the Layering Crystallization of Polymers on Athermal Substrate

“…It is well known that the chain relaxation of a polymer melt increases significantly with the increase of polymer chain length. Therefore, the redistribution of nonconnected monomers are effectively hindered by polymer monomers, and which indicates that the nonconnected monomers coupled to the dynamical relaxation of polymer monomeric are almost ‘frozen’ compared to those nonconnected monomers being largely separated from polymers. For each trapped nonconnected monomer, the corresponding entropic contribution to increase the system free energy is estimated to be kT due to its lowered translational entropy.…”