Formation and Characterization of Covalently Bound Polyelectrolyte Brushes

Abstract

Poly(4-vinylpyridine) (PVP), functionalized at one terminus with a styrenyl group, was end-grafted to vinyl-functionalized self-assembled monolayers by UV irradiation in 1-methyl-2-pyrrolidinone. In this solvent and with oxygen excluded, surface reactions appeared to be selectively limited to the polymer terminus. The dry film thickness was determined by ellipsometry and the grafted amount by FTIR-ATR (Fourier transform infrared spectroscopy in attenuated total reflection). Controlled amounts of positive charge were introduced into the grafted chains by alkylation with a 2.5% solution of CH3I in dimethylformamide (DMF). FTIR-ATR was used to quantify the extent of alkylation, from 10% to 96%. These polyelectrolyte brushes will comprise a model system for studying polyelectrolytes at surfaces.

Protein interactions with bottle-brush polymer layers: Effect of side chain and charge density ratio probed by QCM-D and AFM

“…Instead, the interaction commences at a separation of approximately 10 nm, where a strong attractive force pulls the lysozyme-coated surfaces together. On separation an adhesion force of 0.4 mN/m is measured, which is comparable to the value, 0.4-0.8 mN/m, reported for lysozyme-coated mica surfaces across a 200 ppm lysozyme solution in 1 mM NaCl at pH 5.6 [55]. We note that the attraction on separation and the steric repulsion on approach are of shorter range compared to when lysozyme was allowed to adsorb to PEO 45 MEMA:METAC-10 coated silica.…”

Adsorbed Monomer Analog of a Common Polyelectrolyte

“…above the isoelectric point [6]. In this case, the surface charge was negative; both the polyelectrolyte and the monomer analog adsorbed chiefly by electrostatic attraction to the surface of opposite charge.…”

“…Isotropy of an IR transition moment was equivalent to D 2.05 for the refractive indices of our Si crystal and aqueous solutions. While D is this experiment was probably also influenced by residual roughness of the polished Si crystals (profilometry showed roughness up to 15 Å normal to the surface [6]), it is meaningful to compare relative values of D measured using the same crystal under different solution conditions. In the graphs discussed below, we analyze D of an inplane stretch of the pyridine ring, the carbon-nitrogen stretch at 1644 cm 21 (its intensity was the highest of the IR absorption peaks), but the same effects were measured also for the weaker coupled carbon-carbon and carbon-nitrogen ring stretch at 1523 cm 21 .…”

“…In the graphs discussed below, we analyze D of an inplane stretch of the pyridine ring, the carbon-nitrogen stretch at 1644 cm 21 (its intensity was the highest of the IR absorption peaks), but the same effects were measured also for the weaker coupled carbon-carbon and carbon-nitrogen ring stretch at 1523 cm 21 . The band at 1644 cm 21 is directed along the symmetry axis of P 1 [6] and should reflect the molecular tilt. Figure 1 shows the dependence of the P 1 dichroic ratio on the ratio of Na 1 to P 1 ions in solution; the concentration of P 1 was kept constant at 100 mmole͞ᐉ.…”

“…Adsorption was measured by polarized Fourier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR) using a Biorad FTS-60 spectrometer equipped with a mercury-cadmiumtelluride detector and a home-built adsorption cell [5]. The contribution of nonadsorbed species in solution to an ATR signal can be calibrated by using nonadsorbing surfaces and then subtracted quantitatively [4][5][6]. The effects described below are apparent even in the raw data, however.…”