Paper Number
SM1
Session
Polymers Solutions, Melts and Blends
Title
Mobility of polymer-tethered nanoparticles in entangled polymer melts
Presentation Date and Time
October 21, 2019 (Monday) 9:50
Track / Room
Track 3 / Room 201
Authors
- Ge, Ting (Duke University, Department of Mechanical Engineering and Materials Science)
- Rubinstein, Michael (Duke University)
Author and Affiliation Lines
Ting Ge and Michael Rubinstein
Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708
Speaker / Presenter
Ge, Ting
Text of Abstract
A scaling theory is developed for the motion of a polymer-tethered nanoparticle (NP) in an entangled polymer melt. The mobility of a NP tethered with a single polymer chain (tail) is determined by the competition between the bare particle and the tail, and is dominated by either the particle or the tail, depending on the particle diameter d and the tail size Rtail. If d is smaller than the tube diameter a of the melt, the particle is not directly affected by the entanglement network, but can be dragged to follow the tail in the confining tube for time t above a crossover time τ* in a tail-dominated regime. If d is moderately larger than a, the particle is confined by the entanglement network until the hopping diffusion time τhop, but can then participate in the entangled dynamics of the tail for t > τ* in a tail-dominated regime. If d is sufficiently larger than a, hopping diffusion is suppressed, and a single-tail NP has to wait for the terminal relaxation of the entangled melt to freely diffuse. The mobility of a NP tethered with multiple polymer chains (tails) is studied by comparing the dynamics of the bare particle and that of the branch point of a corresponding entangled star polymer. We propose that the diffusion mechanism for the branch point of an entangled star is pulling by the majority of retracted arms through a gate surrounding the entanglement cell confining the branch point. The time τs for one such diffusion step over a distance ≈a is longer than the arm retraction time τarm by a combinatorial factor. The mobility of a multi-tail NP is approximated as the lower of the mobilities of the bare NP and the branch point of the star polymer.