Competitive and displacement adsorption of polystyrene and poly(ethylene oxide)

Abstract

Competitive and displacement adsorption of polystyrene (PS) and polyethylene oxide) (PEO) with narrow molecular weight distributions onto a nonporous silica (Aerosil 130) from carbon tetrachloride solutions at 35 °C was studied by IR and UV spectroscopy. The fraction of silanol groups occupied by styrene or ethylene oxide units was determined from the shift in the IR frequency of the silanol groups. In competitive adsorption, PEO absorbs preferentially over PS, and the preferential adsorption of large molecules over small molecules occurs even in the presence of different species. PS molecules are completely desorbed from the silica surface by addition of PEO (displacer). The degree of displacement of PS by PEO depends on the fraction of styrene units directly attached to the silanol groups as well as on the molecular weights of PS and PEO.

Heats of adsorption in the mixed polymer systems

“…2, curves 2, 3) an essential diminution of the intensity of the band of free Si-OH groups is observed. Such redistribution of the intensities from the free Si-OH groups to the bound ones is connected with increasing adsorption and with increasing the degree of surface covering [16,18,19]. By transition from adsorption from semidilute solutions to adsorption from concentrated ones (Fig.…”

“…IR spectra of aerosil wetting by CCl 4 with adsorbed polymers (after adsorption and centrifugation) between plates made of KBr for the spectrum registration in the region 2880-4000 cm −1 were recorded according to the method proposed in [18,19]. Each measurement was repeated 2-3 times.…”

Adsorption of organic molecules on silica surface

“…Adam and Robb [220] studied the competitive adsorption between sodium polyacrylate (NaPA) and sodium polystyrene sulphonate (NaPSS) and the displacement adsorption of NaPSS by NaPA on the CaCO 3 surface. In organic solvent, the studies of competitive and displacement adsorption between different polymer species, such as polymethyl methacrylate (PMMA)/polystyrene(PS) [221,222] and polyethylene oxide (PEO)/PS pair on silica surface led to some significant findings: (i) in competitive adsorption, polar molecules adsorb preferentially on silica surface and (ii) in displacement adsorption, large displacer chains have greater exchangeability and adsorbed polymer chains are not easily desorbed from the adsorbing surface [223].…”

Energy of adsorption interaction and surface coverage from polymer of various molecular structures

“…To determine the surface coverage were used the technique proposed in Refs. [9,[12][13][14], in which the integral intensity of bands of stretching vibration of bound and free hydroxyl groups of aerosil was estimated from the data of IR spectroscopy. The fraction of the hydroxyl groups bound by the CTA and PB macromolecules was estimated from the following equations: where S are the relative integral intensities, which are proportional accordingly: S OH, 3660 -to the amount of the free hydroxyl groups; S S, CTA -to the amount of the hydroxyl groups bound by the carbonyl groups of CTA; S S, PB -to the amount of the hydroxyl groups, bound by the CH-groups of PB, neighboring to the double bond.…”