Theory on Capillary Filling of Polymer Melts in Nanopores

Abstract

A unified theory for the imbibition dynamics of entangled polymer melting into nanopores is presented. Experiments demonstrate the validity of t dependence but contradict the predictions of the classical Lucas-Washburn equation because of the prefactor. A reversal in dynamics of capillary filling is reported with increasing polymer molecular weight. Polymer imbibition under nanometer confinement can be discussed by two mechanisms: one is the standard hydrodynamic flow, resulting in a parabolic flow profile. When the inner wall has a strong attraction to the polymer, a layer of immobile chains is created, resulting in an increase of the effective viscosity and to slower imbibition. The other is the reptation model proposed by Johner et al., leading to a plug flow profile and to the reduction in the effective viscosity (faster imbibition). The reversal in dynamics of polymer imbibition can be explained by the competition between these two mechanisms.

Interfacial Interactions During In Situ Polymer Imbibition in Nanopores

“…The nonmonotonic behavior of the effective viscosity on pore size is the result of the competition between the two mechanisms. This effect found experimentally [17] was well captured by theory [19].…”

“…Higher effective viscosities than the bulk are not uncommon during polymer imbibition in nanopores [17][18][19]. Recently, Doi et al [19] constructed a unified theory to describe the imbibition behavior of polymer melts in nanopores. Two different mechanisms were proposed: one is the dead-layer effect due to the adsorption of polymer segments.…”

Solvent-Driven Infiltration of Polymer (SIP) into Nanoparticle Packings

“…In such systems, infiltration time is predicted to follow a linear relationship with chain length (τ~N 1 ). 33 Since R g~N 1/2 in an ideal melt, with a confinement ratio defined by the radius of gyration (λ = R g /〈R〉 pore ), the dynamics should scale as τ~λ 2 (Figure 3). The SIP system passes dynamically from empty to crowded environments within the pore, obeying a power law bounded by the predicted scaling exponents in the dilute and melt regimes.…”

“…The infiltration times for bilayers of various MW with SiO2 NPs with 〈D〉 NP ≈ 7 nm (light blue circles) and 〈D〉 NP ≈ 22 nm (dark blue circles) are shown. The dotted gray lines indicate scaling behavior for melts (λ 2 ) and for dilute solutions (λ 2/3 ) 33,34. SEM images before and after SIP.…”

High‐Performance Packaged 3D Lithium‐Ion Microbatteries Fabricated Using Imprint Lithography

“…Acetonitrile (the solvent) is chosen to fill the 3D porous nickel electrodes before casting the gel solution because it wets well both the active materials and is nonreactive with lithium metal (Figure S4, Supporting Information). Due to the porous nature of the electrodes, acetonitrile rapidly wets the electrodes [ 14 ] (Movies S1 and S2 in the Supporting Information). After the electrodes are filled with acetonitrile, a large excess of PEO acetonitrile solution (10% w/w PEO) is cast on the electrodes and PEO diffuses into the internal pores of electrodes.…”