Modeling adsorption processes of poly-p-phenylenevinylene precursor and sodium acid dodecylbenzenesulfonate onto layer-by-layer films using a Langmuir-type metastable equilibrium model.
The adsorption kinetics curves of poly(xylylidene tetrahydrothiophenium chloride) (PTHT), a poly-p-phenylenevinylene (PPV) precursor, and the sodium salt of dodecylbenzene sulfonic acid (DBS), onto (PTHT/DBS)n layer-by-layer (LBL) films were characterized by means of UV-vis spectroscopy. The amount of PTHT/DBS and PTHT adsorbed on each layer was shown to be practically independent of adsorption time. A Langmuir-type metastable equilibrium model was used to adjust the adsorption isotherms data and to estimate adsorption/desorption coefficients ratios, k=kads/kdes, values of 2x10(5) and 4x10(6) for PTHT and PTHT/DBS layers, respectively. The desorption coefficient has been estimated, using literature values for poly(o-methoxyaniline) desorption coefficient, as was found to be in the range of 10(-9) to 10(-6) s(-1), indicating that quasi equilibrium is rapidly attained.
Marletta
Alexandre
A
Instituto de Física, Universidade Federal de Uberlândia, MG, Brazil. marletta@ufu.br
Silva
Raigna A
RA
Ribeiro
Paulo A
PA
Raposo
Maria
M
Gonçalves
Débora
D
D000327:Adsorption; D001557:Benzenesulfonates / Q000737:chemistry*; D007700:Kinetics; D008956:Models, Chemical; D015394:Molecular Structure; D011145:Polyvinyls / Q000737:chemistry*; D013053:Spectrophotometry
D001557:Benzenesulfonates; D011145:Polyvinyls; C470024:poly(4-phenylenevinylene); C001114:dodecylbenzenesulfonic acid