Аннотация:The forces acting between one surface coated with Langmuir−Blodgett cellulose films and one glass surface have been measured using the MASIF surface force technique. This study is mainly concerned with the effects due to addition of cationic polyvinylamine and changes in ionic strength. The results have implications for the interactions between cellulose and mineral surfaces in the papermaking process. The cellulose surface is weakly negatively charged at pH 5.5−6.0. Polyvinylamine adsorbs to both glass and cellulose surfaces, which first causes charge neutralization and subsequently a charge reversal upon increasing the polymer concentration. The cellulose films swell upon immersion in aqueous solutions as evidenced by the appearance of a short-range steric force barrier. The dynamics of the swelling process was found to be dependent on the ionic strength of the solution. It was found that an increased ionic strength accelerates the swelling, which can be attributed to an increase in surface charge density and hence an increase in the short-range repulsion between individual cellulose chains. The results obtained in this study are consistent with those obtained for the interaction between two glass surfaces in polyvinilamine solutions as described in a previous report. However, the long-range (bridging) attraction observed between two glass surfaces immersed in the polyvinylamine solution was absent between one glass and one cellulose surface. We attribute this to the lower surface charge density of the cellulose surface.
