Direct Measurement of Attractive Forces in an Asymmetric Polyelectrolyte System

✍ Scribed by Mats A.G. Dahlgren

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 73 KB
• Volume: 181
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1996.0423

✦ Synopsis

When immersed in aqueous solution, the mica develops a negative surface charge (8). PCMA is a cationic polyelectrolyte; the sample used has a

In this article are presented results from direct measurements molecular weight M w Å 1.5 1 10 6 g/mol.

of interactions between one polyelectrolyte covered mica surface and one bare mica surface. There is a strong and long ranged attraction between the bare mica surface and the mica surface RESULTS AND DISCUSSION neutralized by adsorbed polyelectrolyte. The attraction is stronger and more long ranged in this asymmetric system than in a corre-When two mica surfaces covered with polyelectrolytes to such an extent sponding symmetric system. This attraction is of the same magnithat the net surface charge is close to zero are brought together, bridging tude in strength in both 0.1 mM KBr and 10 mM KBr solution. attraction (9) causes the spring system of the surface force apparatus to The results support the findings from Monte Carlo simulations become mechanically unstable, which makes the surfaces suddenly move, and mean field calculations presented by Sjo ¨stro ¨m and A ˚kesson. or jump, to the next stable region (10) (to the distance corresponding to a