Surface Characterization and Dissociation Properties of Carboxylic Acid Core–Shell Latex Particle by Potentiometric and Conductometric Titration
✍ Scribed by Seigou Kawaguchi; Ahmad Yekta; Mitchell A. Winnik
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 146 KB
- Volume
- 176
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
of film formation from latex dispersions (1-3). In this ex-Surface characterization of poly( n-butyl methacrylate) periment, we have used poly(n-butyl methacrylate) (PBMA) core-shell latex particle with a shell rich in carboxylic (PBMA) microspheres as a model polymer. The polymer acid groups has been investigated by means of potentiometric and chains interdiffuse across the interface between two particles conductometric titrations. PBMA core-shell latex particle was at higher temperature than the glass transition temperature prepared by semicontinuous three-stage emulsion polymerization.
of the polymer (T g ). Film formation is, therefore, thought Methacrylic acid (MA) was added at the final stage of the polymerto be very sensitive to the nature of substances at the surface ization. Potentiometric titration was carried out on the latex aqueof the latex. Many industrial applications involve latex partious dispersions containing various NaCl concentrations. Concles with a surface rich in carboxylic acid groups (4). These ductometric titration was carried out for the salt-free aqueous dispersion. The total content of ionizable groups was determined are thought to provide an improvement in colloidal stability by conductometric titration in 1,4-dioxane. The MA content in the in the dispersion and enhanced adhesion in the films. If the shell, determined by potentiometric titration, is equal to that by acid content of the particle surface is sufficiently rich, these conductometric titration. This quantity is, however, slightly dispersions will form films with an interconnecting memsmaller than that determined by back titration. We conclude that brane of polar materials. Quite recently, we have investigated about 27% of total ionizable groups is buried in the particle intethe influence of surface carboxylic acid groups of latex partirior. The potentiometric titration behavior of MA groups on the cles on the polymer interdiffusion rate across the interface latex surface is analyzed in detail and compared to theoretical of the particles (5, 6). The interdiffusion rate during the results calculated from a smeared-charge model with spherical film formation was found to be significantly retarded but not symmetry. We determine the negative logarithm of intrinsic dissosuppressed, either by the presence of the carboxylic acid ciation constant of MA at the surface, pK 0 Å 4.8 { 0.2, in groups in the latex shell or by their salts. This result differs agreement with that of low molecular weight isobutylic acid or from the work reported by Joanicot et al. (7, 8). They found poly(methacrylic acid). We find that the electrostatic work required to remove H / from the latex particle surface calculated that poly(acrylic acid) (PAA) at the surface of a poly(styfrom the smeared-charge model is in good agreement with the rene-co-n-butyl acrylate) latex effectively suppressed interexperimental results.