Ultrathin-film multilayer composites

We have developed the use of ultrathin-film multilayer composites, illustrated in Figure 1, as the starting point for the formation of amorphous intermediate states. Ultrathin-film multilayer composites offer several unique advantages over other methods of preparing amorphous solids. These include the ability to monitor the progress of the reaction by X-ray diffraction and scanning calorimetry, the ability to separate the processes of diffusion and phase nucleation, and the ability to obtain thermodynamic data as the reaction progresses. 

Figure 1. Idealized ultrathin-film multilayer composite, section view.

Amorphous networks, 4-5 nAmorphous solid synthesis via ultrathin-film multilayer composites analysis of solid-state reaction mechanisms, 357,358/ application to synthesis of metastable ternary compounds, 366 control of crystallization of amorphous aUoy, 360,363,365-367/ control of formation of homogeneous amorphous alloy, 360,361-36 differential scanning calorimetric procedure, 359-360 grazing measurement procedure, 359 lugb-angje XRD procedure, 359 length sddes vs. course of solid-state reactions, 360,361-362/363 quantitative analysis of interdiffiision reaction, 356-357... 

A thin film composite reverse osmosis membrane can be defined as a multilayer membrane in which an ultrathin semipermeable membrane layer is deposited on a preformed, finely microporous support structure. This contrasts with asymmetric reverse osmosis membranes in which both the barrier layer and the porous substructure are formed in a single-step phase inversion process and are integrally bonded. 

Water-soluble poly(ferrocenylsilane) polycations, belonging to the rare class of main chain organometallic polyelectrolytes, have been reported by us and others [35,36,87,88]. These compounds are of interest because they combine the imusual properties of poly(ferrocenylsilane)s with the processabiUty of polyelectrolyte solutions—for example, enabling one to make use of ionic interactions to deposit these polymers onto substrates. Polyelectrolytes can be employed in layer-by-layer self-assembly processes to form ultrathin multilayer films with controlled thickness and composition [89,90]. 

One interesting aspect of the application of IR spectroscopy relates to thin (micrometer) and ultrathin (<50 nm) polymer films, polymer surfaces, and polymer-substrate interfaces [23]. So-called external reflection methods can be used to determine the important properties of thin films (comprising monolayers and multilayers) such as thickness, anisotropy, molecular orientation, and composition. The most frequently applied methods include IR ellipsometry (IRE) [63-67] and IR reflection absorption spectroscopy (IRRAS), which may also be referred to as reflection absorption infrared spectroscopy (RAIRS) [1,23]. 

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