Characterization of Interfacial Properties of End-Functionalized Poly(ethylene glycol)s
Abstract
Monodisperse poly(ethylene glycol)s with one or two chain ends functionalized with perfluorononadecanoyl groups were used to study the adsorption of polymers at free interfaces. Blends of end-capped PEGs (PEO-R or R-PEO-R) with PEGs of the same MW were cast as thin films. Due to the surface activity of the perfluoroalkyl end group, the PEO-R terminally adsorb to the polymer surface to form polymer tails, while the R-PEO-R form tails and/or loops depending on MW and temperature. The surface concentration of the perfluoroalkyl end groups was determined by x-ray photoelectron spectroscopy. It was observed that the perfluoroalkyl chain ends adsorb to the polymer surface, leaving a depletion zone with little fluorine near the surface. The adsorption isotherm can be described by the Langmuir equation. It was found that when the bulk concentration of the end-capped PEGs is low, the surface concentration of the end group is linearly dependent on bulk concentration, indicating the absence of interactions between the adsorbed polymer coils, i.e. the adsorbed polymer forms a "mushroom" structure. At high surface coverage, the adsorbed polymers are highly stretched in a "polymer brush" conformation. The dependence of the adsorption behavior on MW and temperature have been characterized.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.N2901S