Multilayer films fabrication

The first example of a patterned heterostmctured organometaUic multilayer film, fabricated from 5 and poly(sodium vinylsulfonate) on a substrate featuring CHS- and OH-terminated alkanethiol monolayer areas, appeared on the cover of Macromol. Rapid Commun. 22(1), 2001. 

To form electrically conducting monolayers of polypyrrole, 3-oct ecanoyl pyrrole must be mixed with an excess of pyrrole monomer and spread onto an oxidizing subphase. The FTIR spectra of the multilayer films fabricated from these mixed electrically conductive monolayers (Figure 12) indicate that the 3-octadecanoyl pyrrole molecules assume a molecular (mentation very similar to that obtained in their native multilayo films. This can be clearly seen by the similar polarization dependence observed for the multilayer films containing both pure 3-ODOP and polypyrrole/3-ODOP. Thus, the hydrocarbon tails of the surface active molecules are tilted away from the surface normd with a tilt angle estimated in this case to be about 25° and the pyrrole head groups are oriented nearly parallel to the plane of the substrate. 

Buck ME, Breitbach AS, Belgrade SK, Blackwell HE, Lyim DM (2009) Chemical modification of reactive multilayered films fabricated from poly(2-alkenyl azlactone)s design of... 

FIGURE 15.15 Schematic description of the fabrication of multilayer films of GOx onto CNTs. 

CdS/ZnS Multilayer Thin Films. The low deposition temperature of SILAR allows the growth of very thin layers to achieve multilayer structures. CdS/ZnS multilayer films have been grown from separate cadmium, zinc, and sulfur precursor solutions. Multilayer structures with layer thicknesses of 2-5 nm have been fabricated, and the separate layers could be seen by SEM. RBS measurements revealed that the layers were separated with only... 

Recently, Jen s group synthesized a series of high Tg fluorinated polymers with a hole transporting TPA group covalently attached as side chains (55) (Scheme 3.21) [99]. This type of polymer can be processed into thin films by simple thermal cyclopolymerization without introducing any by-products [100]. The polymers (56, 57) are insoluble in most organic solvents and can be conveniently streamlined into a multilayer device fabrication process [101,102]. The... 

The reason for Nafion LB-film fabrication was the wish to obtain the highly ordered systems from perfluorinated ion exchange polymer with multilayered structure, where the ionic layers (conductors) would alternate with fluorocarbon polymer layers (insulators), and to investigate the properties of such films.74 This polymer contains a hydrophobic fluorocarbon polymeric chain and hydrophilic ionic groups, so it is sufficiently amphiphilic it has a comblike structure that makes it a suitable polymer for LB-film deposition. 

Electron Beam Lithography. LB PMMA films with thicknesses of 6.3 nm (7 layers) are sufficient for patterning a Cr film suitable for photomask fabrication. For ultrathin PMMA films the resolution (see Fig. 1) is limited by the smallest spot diameter available on MEBES I (1/8 pm). However, it is not possible to obtain this resolution if a thicker resist (>100 nm) is used under the same exposure and development conditions, which demonstrates that ultrathin resists are able to minimize the proximity effect. Also, since the radius of gyration of 188,100 Mw PMMA is about 10 nm in the bulk, and the thickness of the 7 layer film (6.3 nm) is less than 10 nm, it is reasonable to assume there must be an alteration of chain configuration in the ultrathin films. This will be particularly true when the post-deposition baking temperature of the multilayer films is less than the glass transition temperature (115°C), as is the case for the present experiments. In such a case, interdiffusion of PMMA chains between the deposited layers may not result in chain configurations characteristic of the bulk. 

Fabrication of organic thin films based on sponfaneous molecular assembly has been considered as one of fhe powerful approaches to create novel supramolecular systems. In this context, multilayer films were fabricated by layer-by-layer electrostatic deposition techniques based on the electrostatic interaction between dsDNA and the positively charged polymer poly(diallyldimethylammonium chloride) (PDDA) on GC surfaces. A uniform assembly of PDDA/DNA multilayer films was achieved, based on the adsorption of the negatively charged DNA molecules on the positively charged substrate [55]. 

FIGURE 4. (a) Structures of PPVG and PEDOT PSS. (b) The fabricating of the polyelectrolyte-organometallic multilayer film by the layer-by-layer deposition process. 

Electrostatic assembly, which involves attractive forces between two oppositely charged entities (polymers, nanoparticles, and substrates), has been proposed in the pioneering work of Her for the assembly of two- and three-dimensional structures.22 The LbL assembly of charged polyelectrolytes was later reported by Decher et al. for the fabrication of multilayer films of polyelectrolytes.10 23 Their technique is based on the consecutive adsorption of polyanions and polycations from dilute aqueous solutions onto a charged substrate (Fig. 13.2). 

In respect to thin films of dendritic polymers, many investigators have fabricated different types of films such as multilayers of amine-terminated PAMAM dendrimers on a silicon wafer [34], covalent attachment of amine-terminated PAMAM dendrimers [35] and poly(iminopropane-l,3-diyl) dendrimers [36] on thiol SAMs, self-assembled composite multilayer films from amine- and... 

Layer-by-layer (LBL) deposition has become one of the major techniques to fabricate multilayer films. It was introduced by Decher in the form of alternate deposition of cationic and anionic polyelectrolytes [56-58]. This so-called electrostatic self-assembly process dominates the research in this area. However, more recently alternative driving forces have been employed, such as hydrogen bonding, coordination bonding, charge-transfer interactions, and covalent bonding. Since this review concerns the formation, functionaliza-... 

Fig. 38 Illustration of the LBL fabrication of multilayer films based on hydrogen bonding between PAA and P4VP. Reprinted with permission from [254]. 1999 American Chemical Society...

To fabricate different polymer layers in a device using solution based techniques, mutually exclusive solvents have to be identified, which is often very difficult. CVD eliminates these difficulties and excellent heterojunctions and multilayered films can be fabricated relatively easily. Also, the capability to co-deposit compounds can be achieved. This ease of co-depositing compounds has enabled the synthesis of several inorganic-organic hybrids, which can also be tailored as nanocomposites at the molecular level. 

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