Sandwich polymers

Figure 4.34 Sandwich polymer of the SCN complex of 4.80 (Hg and SCN atoms shown as spheres).60...

Figure 5-21 Preparation of fulvalene-linked carborane sandwich oligomers (a) and diboro-lyl sandwich polymers (b and c).

Adhesive joints are not, however, the only applications of adhesion. Adhesion is involved whenever solids are brought into contact, as in coatings, paints, and varnishes multilayered sandwiches polymer blends filled polymers and composite materials. Since the final performance of these multicomponent materials depends significantly on the quality of the interface that is formed between the solids, it is understandable that a better knowledge of the adhesion phenomenon is required for practical applications. 

These materials, unlike the other nanophase materials described in this chapter, are nano-sized in only one dimension and thereby act as nanoplatelets that sandwich polymer chains in composites. Mont-morillonite (MMT) is a well-characterized layered silicate that can be made hydrophobic through either ionic exchange or modification with organic surfactant molecules to aid in dispersion [5,23]. Polymer-layered silicates may be synthesized by exfoliation adsorption, in situ intercalative polymerization, and melt intercalation to yield three general types of polymer/clay nanocomposites. Intercalated structures are characterized as alternating polymer and siHcate layers in an ordered pattern with a periodic space between layers of a few nanometers [13], ExfoHated or delaminated structure occurs when silicate layers are uniformly distributed throughout the polymer matrix. In some cases, the polymer does not intercalate... 

Some examples of the applications of AC electrogravimetry to the study of the redox switching of inorganic and organic films are now reported. First, details about Prussian blue, where mainly cation movement can be detected, will be given. Then, the behaviom of PPY, where cations, anions and solvent participate in the charge compensation process, will be described. Finally, a system of sandwiched polymers will be analysed. 

The greatest concern with PVC is as a contaminant in other polymers being recycled, particularly PET. Approximately 12 million pounds of PVC was recycled in 1993, about half from packagiag (25). AppHcations for recycled PVC iaclude as an inner layer sandwiched between two virgin PVC layers in pipe and sheet for bHster packagiag and other packagiag appHcations. 

Both the polymers are dark in color and exhibit semiconductivity and paramagnetism. The electric conductivity measurements are performed on peUets and on thin films in sandwich and surface ceUs. 

Many polymers, including polyethylene, polypropylene, and nylons, do not dissolve in suitable casting solvents. In the laboratory, membranes can be made from such polymers by melt pressing, in which the polymer is sandwiched at high pressure between two heated plates. A pressure of 13.8—34.5 MPa (2000—5000 psi) is appHed for 0.5 to 5 minutes, at a plate temperature just above the melting point of the polymer. Melt forming is commonly used to make dense films for packaging appHcations, either by extmsion as a sheet from a die or as blown film. 

Sample cells include Lindemann/capillary tubes (normally < 1 mm in diameter) and aluminium holders. In the latter, thin aluminium windows sandwich the sample in a cylindrical aluminium sample holder. The diffraction from the aluminium is observed in this case, and may be used as a calibration standard. For low-temperature materials, the aluminium window can be replaced by the polymer Kapton. Beryllium may also be used [14]. Sample volumes of between 50 and 100 pL are typically required. 

The simplest polymer-based EL device consists of a single layer of semiconducting fluorescent polymer, c.g., PPV, sandwiched between two electrodes, one of which has to be transparent (Fig. 1-1). When a voltage or bias is applied to the material, charged carriers (electrons and holes) are injected into the emissive layer and these earners arc mobile under the influence of the high (> 105 V enr1) elec-... 

---