RESUMEN
The preparation and characterization of mono- and multilayers of cellulose acetate (CA) Langmuir-Blodgett films on indium tin oxide and gold surfaces were studied in detail for the first time. These layers were characterized by their thickness, wettability, morphology and structure using various surface techniques. The thickness of a monolayer of CA based on XPS measurement was one nanometre. Multilayers of CA Langmuir films were homogeneously transferred onto solid surfaces. The permeation of different molecules across these films was studied using electrochemistry in various redox solutions. Our findings suggest that a membrane like structure is formed, which is less permeable as the number of layers increases. Finally, potential applications of these ultrathin films as supports for accommodating biomolecules or metal nanoparticles are presented.
RESUMEN
A new approach based on measuring the change of the open-circuit potential (OCP) of a hanging mercury drop electrode (HMDE), modified with alkanethiols of different chain length conducted in a solution containing a mixture of Ru(NH3)6(2+) and Ru(NH3)6(3+) is used for studying electron transfer across the monolayer. Following the time dependence of the OCP allowed the extraction of the kinetic parameters, such as the charge transfer resistance (R(ct)) and the electron transfer rate constant (k(et)), for different alkanethiol monolayers. An electron tunneling coefficient, beta, of 0.9 A(-1) was calculated for the monolayers on Hg.