ma9b01383_si_001.pdf (1.02 MB)
In Situ Monitoring of the Imbibition of Poly(n‑butyl methacrylates) in Nanoporous Alumina by Dielectric Spectroscopy
journal contribution
posted on 2019-10-18, 19:16 authored by Chien-Hua Tu, Martin Steinhart, Hans-Juergen Butt, George FloudasThe
imbibition dynamics of poly(n-butyl methacrylate)
(PnBMA) in nanoporous alumina is studied by in situ dielectric spectroscopy at temperatures in the range 30–50
K above the glass temperature. A model provides the imbibition length
from the measured dielectric strength of the segmental process. The
relaxation times of the segmental process during imbibition are isochronal,
except at early stages where a speed-up is observed. Furthermore,
as polymer segments flow inside the pores, the distribution of relaxation
times remains constant (Havriliak–Negami shape parameters similar
to the bulk). Imbibition at longer length scales associates with the
effective viscosity of the chains and provides a stringent test of
the Lucas–Washburn equation applicable to Newtonian liquids.
The equation fails to describe the imbibition process because the
prefactor to the t1/2 (t; time) dependence does not adequately describe the process. Imbibition
of polymer blends composed of long and short chains reveals the enrichment
of the pores by the shorter chains by their faster imbibition with
possible application in fractionation.