TRANSPORT IN ORIENTED ULTRATHIN FILMS (FLUORESCENCE QUENCHING, QUENCHING, MASS TRANSPORT, L B FILMS)

Available from UMI in association with The British Library. Requires signed TDF.; The transport properties of ultrathin Langmuir-Blodgett films have been studied by diffusion-sensitive fluorescence quenching techniques and by conventional mass transport techniques. Fluorescence quenching experiments measured the Stern-Volmer quenching parameters of oxygen on the fluorescence emission of an amphiphilic fluorescent probe, pyrenedecanoic acid included in the films at low concentration. Quenching was studied as a function of oxygen concentration, temperature and L-B film composition.; Mass transport measurements were made using L-B films deposited onto porous polypropylene membranes. Both monomeric and polymeric L-B systems were studied as were alternating L-B multilayers and L-B films formed from mixed monolayer systems. Mass transport measurements were made as a function of number of layers deposited, temperature and L-B film composition.; Mass transport was found to be highly sensitive to faults in the L-B films and appeared to be dominated by porous effusion through the faults rather than by permeation through the L-B film.; The results obtained from fluorescence quenching measurements and from mass transport measurements are compared by calculating predicted mass transport coefficients for L-B multilayers from fluorescence quenching data.; The role of L-B film structure with respect to fault density and permeation characteristics are discussed together with strategies which might be employed to improve the structural properties of L-B films used for applications such as membrane separation by the use of mixed and alternating films systems.