Increase in the effective viscosity of polyethylene under extreme nanoconfinement

Tian Ren; Zachary R Hinton; Renjing Huang; Thomas H Epps 3rd; LaShanda Korley; Raymond J Gorte; Daeyeon Lee

doi:10.1063/5.0185144

Increase in the effective viscosity of polyethylene under extreme nanoconfinement

J Chem Phys. 2024 Jan 14;160(2):024909. doi: 10.1063/5.0185144.

Authors

Tian Ren^{1

2}, Zachary R Hinton^{2

3

4}, Renjing Huang¹, Thomas H Epps 3rd^{2

3

4}, LaShanda Korley^{2

3

4}, Raymond J Gorte^{1

2}, Daeyeon Lee^{1

2}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
² Center for Plastics Innovation, University of Delaware, Newark, Delaware 19716, USA.
³ Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA.
⁴ Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, USA.

PMID: 38214386
DOI: 10.1063/5.0185144

Abstract

Understanding polymer transport in nanopores is crucial for optimizing heterogeneously catalyzed processes in polymer upcycling and fabricating high-performance nanocomposite films and membranes. Although confined polymer dynamics have been extensively studied, the behavior of polyethylene (PE)-the most widely used commodity polymer-in pores smaller than 20 nm remains largely unexplored. We investigate the effects of extreme nanoconfinement on PE transport using capillary rise infiltration in silica nanoparticle packings with average pore radii ranging from ∼1 to ∼9 nm. Using in situ ellipsometry and the Lucas-Washburn model, we discover a previously unknown inverse relationship between effective viscosity (ηeff) and average pore radius (Rpore). Additonally, we determine that PE transport under these extreme conditions is primarily governed by physical confinement, rather than pore surface chemistry. We refine an existing theory to provide a generalized formalism to describe the polymer transport dynamics over a wide range of pore radii (from 1 nm and larger). Our results offer valuable insights for optimizing catalyst supports in polymer upcycling and improving infiltration processes for nanocomposite fabrication.