Infrared Study of the Kinetics and Mechanism of Adsorption of Acrylic Polymers on Alumina Surfaces

Abstract

In this paper, we studied the kinetics of the adsorption of poly(methyl methacrylate), PMMA, onto native aluminum oxide surfaces by X-ray photoelectron spectroscopy and reflection-absorption infrared spectroscopy, with the intent of tracking the various changes observed in the infrared spectrum of the adsorbed polymer layer as a function of adsorption time. Specifically, we utilized the relative changes in the absorption bands of the carbonyl, carboxylic acid, and carboxylate groups to determine the sequence of events that culminate in the formation of bonds between carboxylate groups on hydrolyzed PMMA and specific sites on the aluminum oxide surface. We have shown that the adsorption process involves the hydrolysis of a fraction of the methoxy groups of the PMMA to generate COOH groups. Unlike previous assumptions, the formation of COOH groups on the PMMA chains does not constitute a sufficient condition for the actual chemisorption of the polymer chains onto the metal oxide surface. To promote bonding, the acid groups must undergo dissociation to form the carboxylate groups, followed subsequently by actual bond formation, that is, active anchoring, on the surface. This process is mediated by the aluminum oxide sites on the surface in the presence of water. Hence, the adsorption process occurs via a two-step mechanism, in which the first step, that is, the hydrolysis step, is a necessary but insufficient condition and the second step, that is, the anchoring step, is largely dependent on the type of interfacial chemistry possible for a particular polymer-metal oxide surface, the polymer conformation, the molecular weight, and the flexibility of the adsorbing molecules.

Adhesive Bonding and Corrosion Performance Investigated as a Function of Aluminum Oxide Chemistry and Adhesives

“…Hence, the slight increase in peel strength after the transition from dry-to wet peel in here may be related to increased interfacial interactions in the presence of the weakly acidic phenols that are leached out of the resin in the presence of water to temporarily stabilize the interface 44 (since, as found earlier in Abrahami et al 24 , these reactions are reversible). This behavior has also been observed with other polymers including a study with poly(methyl methacrylate) (PMMA) polymer, Tannebaum et al 45 found that water helps to mediate bonding. Similar observations were recently reported by Pletincx et al 46 using in-situ measurements, showing that water can stabilize the formation of carboxylate bonds on native aluminum oxides.…”

Deacidification of Acidic Books and Paper by Means of Non-aqueous Dispersions of Alkaline Particles: A Review Focusing on Completeness of the Reaction

“…In particular, the protonated and carboxylate forms of carboxylic acid groups can be distinguished (Pappas et al 1999;Ayora-Cañada and Lendl 2000;Dioumaev 2001;Tannenbaum et al 2004).…”

“…In principle, the intensities of absorption bands detectable by infra-red analysis can be used to estimate the relative amounts of protonated vs. dissociated carboxylic acid groups in cellulosic material (Pappas et al 1999;Ayora-Cañada and Lendl 2000;Dioumaev 2001;Tannenbaum et al 2004). Because infrared analysis can involve overlapping peaks, especially in the case of unknown samples, there will be a need for further research of this type when applied to practical samples of paper.…”

A stable lead halide perovskite nanocrystals protected by PMMA

“…To bond the Pb cations of perovskite NCs, polymethyl methacrylate (PMMA) was introduced on HOIP NCs by LAR method. A strong attractive interaction brings about a compact interface [28,31,32], which can effectively retard the diffusion of water into NCs for the decreased intermolecular spaces. Due to the ester carbonyl groups of PMMA, the obtained composite HOIP films show good quality, pure colors and ultrahigh stability against heat and water.…”