Chelates, metallized polymer films

Preparation and Characterization of Metallized Polymer Films Formed from Poly[4- tereph-thaloylamino) salicylic acid hydrazide]-Metal Chelates... 

In past few years, metallized plastics have received considerable industrial and academic attention because of their useful applications. They possess the properties of both the polymer and the metal. There are several techniques for the plastic metallization, but these can be divided into three major categories. First is a metal blending process in which the polymer is mixed with a metal powden Second is a metal deposition process in which the pt ymer film is coaled with a thin metallic layer Third is a metal complexation process in which the polymer is chelated with a metal salt Due to reduction of the mechanical properties of the polymer in the first process and the trouble as well as high cost of the second process which often requires several surface treatments to enhance the adhesion between the metal and the polymer metal-polymer chelates, which are often prepared by reacting the solutions of a polymer and a metal salt, have attracted significant interest because of their resulting solubility and easy processability into films and fibers... 

Although the chelates prepared by the soaking method showed variation of their IR spectra similar to that for those prepared by the mixing method (Ikble H), their element analyses were unsatisfactory to predict similar mixed chelate structure. The soaked chelates were generally found to contain smaller metal content relative to that of the mixed chelates. This indicates that successful chelating occurs readily at the polymer film surface but complete penetration of the metal cation into the core of the film is restricted. 

The synthesis of several metallized PTASH films via coordination of the polymer to various transition metal salts followed by a chemical reduction of the resulting chelates films is described. Coordination reaction was carried out either by the mixing or the soaking method. The metallized films showed novel functions due to characteristic properties of metal chelates. The incorporation of metals improved the tensile strength as well as thermal stability of the systems as evidenced by mechanical properties and TGA measurements This improvement could be clearly demonstrated in chelates prepared by the mixing method rather than those prepared by the soaking method. Metallization of the these films has been shown by SHM, X-my diffraction and ESCA measurements which indicated the presence of the metal adhered to the surface of the films Finally, potential advantages of these metallized films lie in their versatility with which their synthesis and processability can be accomplished as well as in their stability towards humid environment. 

Poly(amic acids) prepared from diamines and pyromellitic anhydride react with metal acetylacetonates to yield polymers with chelated metal ions (i). These products form tough films, which indicated that the initially high molecular weight of the poly(amic acid) was retained on chelation. Heating these products gave electrically conductive materials containing free metal (i). 

Metal complexes with, e.g., phenantroline derivatives, could be (electro-) polymerized to form electroactive films [203, 632-637], Polymeric complexes of nickel allowed a switching of the mechanical properties of the film according to the redox state and the presence of barium ions [638], Dissolution of sacrificial metal electrodes into electrolytes containing chelating polymer provided the desired electroactive films [639, 640]. Even mixed metal polymers (containing, e.g., Pd and Cu) have been constructed, which are very useful for catalytic purposes [194]. 

UV absorbers have been found to be quite effective for stabilization of polymers and are very much in demand. They function by the absorption and harmless dissipation of the sunlight or UV-rich artificial radiation, which would have otherwise initiated degradation of a polymer material. Meyer and Geurhart reported, for the first time in 1945 [10], the use of UV absorber in a polymer. They found that the outdoor life of cellulose acetate film was greatly prolonged by adding phenyl salicylate (salol) [10]. After that, resorcinol monobenzoate, a much more effective absorber, was introduced in 1951 [11] for stabilization of PP, but salol continued to be the only important commercial stabilizer for several years. The 2,4-dihydroxybenzophenone was marketed in 1953, followed shortly by 2-hydroxy-4-methoxybenzophenone and other derivatives. Of the more commonly known UV absorbers, the 2-hydroxybenzophenones, 2-hy-droxy-phenyl-triazines, derivatives of phenol salicylates, its metal chelates, and hindered amine light stabilizers (HALS) are widely used in the polymer industry. 

In order to quantify the transition metal ion concentration, Jones et al. [107] developed a highly sensitive fluorescent chemosensor in the form of dialkoxy-phenyleneethynylene-thiophene copolymers 68/69. The PAEs were functionalized on the thiophene unit with terpyridine (68), and included 2,2 -bipyridine (69) as a Lewis acid receptor. The terpyridine polymers [108] were found to respond quantitatively to transition metal ions at concentrations as low as 4x10 M (NP, Hg, Cr ", and Co " ). The additionally used bpy-PAE demonstrates that variation in the chelation at the receptor site is an important variable in tuning selectivity. The observed dynamic quenching mechanism, combined with the solubility of this material, provides the opportunity to extend these initial investigations to thin solid films for use in real-time monitoring applications. 

DeNicola and Bell report the use of bibenzoylmethane and l-(0-hydroxyphenyl)-3-phenyl-1,3-propanediol as wet adhesion promoters for epoxide resin adhesives on low-carbon mild steel [77]. Metal chelating O-hydroxybenzlamine compounds are stated to produce adhesion-promoting films on metals [78], and improved adhesion to titanium is claimed for metal alkoxide primers. Oxazolidines containing trialkoxy or triaryloxysilyl groups are claimed to be adhesion promoters on metallic substrates [79]. Improved adhesion of epoxide resin adhesives to copper substrates can be achieved by pretreatment in a weak solution of a benzoheterocyclic(thiol) compound [80] and benzotriazole and derivatives have been claimed to improve the bond between vinyl polymers and steel [81] and the adhesion of photosensitive compounds to polymeric substrates [82]. Pesetski and Aleksandrova describe the use of dicarboxylic acids as primers for polyamide films on copper [83],... 

The same authors used the tridentate chelating sites created by an acyl hydrazide condensed with a pyridyl aldehyde to complex metal ions, thereby combining covalent and coordination linkages within one system. As in their earUer work, luminescent properties of films were changed by simply bringing the films into contact. When two nonluminescent films (polymer 1 and 2, Figure 6.3) were stacked on each other and allowed to blend at moderate temperatures, two... 

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