pH-induced release of polyanions from multilayer films.
We discovered pH-induced selective desorption and readsorption of weakly acidic polymers from polyacid or polybase layer-by-layer films. In situ attenuated total reflection Fourier transform infrared spectroscopy confirms the selectivity of polyacid release and shows that film response is caused by pH-induced charge imbalance. Experimentally the characteristic time of chain release tau scales with molar mass M as M(1.1+/-0.1). A new theoretical model of "sticky gel electrophoresis" of entangled polyacids agrees with experiments and predicts tau approximately MH, where H is film thickness. Neutron reflectivity shows that polyacid release results in disordering of the film structure.
Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
Eugenia
E
Kharlampieva
John F
JF
Ankner
Michael
M
Rubinstein
Svetlana A
SA
Sukhishvili
D006863:Hydrogen-Ion Concentration; D011073:Polyamines / Q000737:chemistry; D000071228:Polyelectrolytes; D011108:Polymers / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity
D011073:Polyamines; D000071228:Polyelectrolytes; D011108:Polymers; D011109:Polymethacrylic Acids; D011145:Polyvinyls; C030613:polymethacrylic acid; C019535:poly(4-vinylpyridine)