ma6b00111_si_001.pdf (221.68 kB)
Swelling of Hydrophilic Polymer Brushes by Water and Alcohol Vapors
journal contribution
posted on 2016-05-25, 18:48 authored by Casey
J. Galvin, Jan GenzerWe
examine the effect of end-tethering, grafting density (σ),
chemistry of polymer side chain, and solvent type on the vapor swelling
of hydrophilic polymer brushes. Using a library of samples derived
by postpolymerization modification of a poly(2-(dimethylamino)ethyl
methacrylate) (PDMAEMA) brush, we determine the extent of vapor swelling
and solvent uptake at different vapor pressures of water, methanol,
and ethanol using spectroscopic ellipsometry. We compare the results
from neat PDMAEMA and PDMAEMA quaternized by methyl iodide with chemically
analogous samples prepared by spincasting bulk PDMAEMA. We find that
brush samples swell to greater extents than spuncast samples, indicating
a role for end-tethering in the vapor uptake process. Furthermore,
vapor swelling of polymer brushes depends strongly on both polymer
and solvent chemistry. We demonstrate that the extent to which σ
affects vapor sorption inside the brush depends on polymer side chain
chemistry, indicating an interdependence of the observed parameters
on each other. The implications of these findings for the use of polymer
brushes in technologies such as vapor sensing applications are discussed.