Poly films assembly

Weak polyelectrolytes, on the other hand, become ionized within a specific pH range, creating a mechanism for the disassembly of the polymer multilayers. The most common examples of weak polyelectrolytes include polyacids, such as poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMA). A decrease in the pH below the pKa of the polymer decreases the charge on the polymer, thus destabilizing the electrostatic interactions within the multilayers. The properties of films assembled from weak polyelectrolytes are highly dependent on the charge density, which can be tuned by both the salt concentration and pH [10]. 

Han GY, Guo B, Zhang LW, Yang BS (2006) Conductive gold films assembled on electrospun poly(methyl methacrylate) fibrous mats. Adv Mater 18 1709-1712... 

To create responsive membranes, poly(L-alanine) brushes were grown on the surface of the nanopores in silica colloidal films assembled on Pt electrodes (opal electrodes) according to Scheme 8.6 [33]. The polymerization time was varied from 7 min to 6 h to create polymer brushes of various lengths. 

Fig. 37.10 (A) Low and (B) high magnification scanning electron micrographs of a poly(3-hexylthiophene) film that was deposited onto a YBa2Cu3O7-s/MgO(100) thin-film assembly using a spray-coating procedure with tetrahydrofu-ran as the solvent.

Lenk T J, Hallmark V M, Rabolt J F, Haussling L and Ringsdorf H 1993 Formation and characterization of self-assembled films of sulphur-derivatized poly(methyl methacrylates) on gold Macromolecules 26 1230-7... 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

FIG. 8 Si02 AFM image of six bilayers in situ self-assembled layer-by-layer films of polypyrrole coated with Si02 and poly(styrene sulfonate). 

P.L. He, N.F. Hu, and G. Zhou, Assembly of electroactive layer-by-layer films of haemoglobin and poly-cationic poly(diallyldimethylammonium). Biomacromolecules 3, 139-146 (2002). 

J. Tian, C.-C. Wu, M.E. Thompson, J.C. Strum, and R.A. Register, Photophysical properties, self-assembled films, and light-emitting diodes of poly(p-pyridylvinylene)s and poly(p-pyridinium vinylene)s, Chem. Mater., 7 2190-2198, 1995. 

The major drawback of poly(p-xylylene) is that it reverts to a monomer when thin films are heated above ca. 400°C and it cracks when the films are annealed at 300-350°C in nitrogen. During module assembly the chip-joining (soldering)... 

Full generation poly(amidoamine) (PAMAM) dendrimers possessing amino surface groups are easily spread by spin coating on a mica surface to form films. Interdendrimer assembly events appears to influence these operations. Regardless of the generation levels examined, the film uniformity is determined primarily by the concentration of the dendrimer solution. 

Pinto MR, Rristal BM, Schanze KS (2003) A water-soluble poly(phenylene ethynylene) with pendant phosphonate groups. Synthesis, photophysics, and layer-by-layer self-assembled films. Langmuir 19 6523-6533... 

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