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Interfacial properties of polyelectrolyte‐cellulose systems. IV. Electrokinetic properties of carboxymethylcellulose fibers with adsorbed multilayers of cationic polyelectrolyte
Author(s) -
Onabe Fumihiko
Publication year - 1979
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1979.070240706
Subject(s) - polyelectrolyte , electrokinetic phenomena , streaming current , zeta potential , monolayer , adsorption , cationic polymerization , polymer , ionic strength , chemistry , counterion , chemical engineering , polyelectrolyte adsorption , double layer (biology) , cellulose , layer (electronics) , polymer adsorption , electrophoresis , polymer chemistry , chromatography , organic chemistry , ion , aqueous solution , biochemistry , nanoparticle , engineering
Zeta potential measurements by the streaming current method were performed on carboxymethylcellulose (CMC) with and without irreversibly adsorbed multilayers of cationic polyelectrolyte. Factors affecting the electrokinetic properties such as the amount of adsorbed polymer, polymer molecular weights ( M n 50,000 and 200,000), ionic strength (10 −5 ∼ 10 −2 M KCl), and pH of the streaming medium (KCl solutions) were examined. The negative zeta potential of CMC decreased to the point of monolayer formation and increased from that point to the saturated multilayer formation. The polarity of the zeta potential was negative throughout every adsorption stage. The negative zeta potential increase was attributed to: (a) binding of anions (Cl − and OH − ) to the outermost layer of the multilayer from KCl solutions and (b) change in chemical potentials of counterions in a diffuse double layer due to expansion of the double layer in the presence of the adsorbed multilayer on CMC. The results suggest that the carboxyl groups under the monolayer are undetectable electrokinetically; however, the negative charge, due to unneutralized carboxyl groups under the monolayer, appears to cause further adsorption forming a saturated multilayer. When the effect of unneutralized carboxyls of CMC are shielded at higher levels of adsorption, the outermost layer of the multilayer becomes a potential‐determining layer.