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Formation of alkane‐phosphonic acid self‐assembled monolayers on alumina: an in situ SPR study
Author(s) -
Koutsioubas Alexandros G.,
Spiliopoulos Nikolaos,
Anastassopoulos Dimitris L.,
Vradis Alexandros A.,
Priftis George D.
Publication year - 2009
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.3116
Subject(s) - monolayer , chemistry , kinetics , alkane , phase (matter) , adsorption , surface plasmon resonance , self assembled monolayer , kinetic energy , analytical chemistry (journal) , organic chemistry , nanotechnology , materials science , catalysis , nanoparticle , biochemistry , physics , quantum mechanics
The formation process of n ‐alkane phosphonic acid CH 3 (CH 2 ) n −1 PO(OH) 2 ( n = 10,12,14,18) self‐assembled monolayers (SAMs), deposited from ethanol solutions on aluminum oxide, has been monitored in situ using surface plasmon resonance (SPR) spectroscopy. In addition, the two‐solvent approach is used to obtain both film thickness and refractive index of the fully formed adsorbed layers. A densely packed adsorbed layer is formed only for the longest molecules with n = 18. The chain length and solution concentration dependence of formation kinetics are studied, and the existence of two distinct kinetic steps is revealed. Fittings of the experimental results with various kinetic models are performed. Our analysis suggests that during the first kinetic step, a transition from a lying‐down to a standing‐up phase takes place, and the growth of this standing‐up phase is governed by second‐order kinetics. The second slow kinetic step is described by a modified first‐order Langmuir law. Copyright © 2009 John Wiley & Sons, Ltd.