Poly chromicities

Intramolecular excimer and exciplex formation has been used to study the structure and mobility of chain segments in poly-chromic systems. A review of the results of these studies can be found in ref. 9. 

ABS plastic, a polymer consisting of polybutadiene spheroids is dispersed in a continuous phase of poly(styrene—acrylonitrile). The chromic acid attacks the polybutadiene at a much higher rate than the continuous phase. This gives an excellent microroughened surface with superior metal-to-plastic bond strength. A typical recommended formulation consists of 20 vol % sulfuric acid, 420 g/L chromic acid, and 0.1—1.0% of a fluorocarbon wetting agent. The plastic is treated with this formulation for 6—10 min at 60—65°C. 

On zinc phosphate conversion coatings, the "Mannich" derivatives of poly-4-vinylphenol have demonstrated performance equivalent to chromic chromate systems in salt spray, humidity, and physical testing. In addition. Table III illustrates results observed with automotive body paint systems evaluated by the "scab" or "cycle" test which causes failure more typical of actual end use conditions than do salt spray evaluations. Again, results equivalent to chromic-chromate post-treatments were obtained. In addition, the humidity resistance and adhesion tests were essentially equivalent to the chromium controls. 

A compound prepared and first described as nicotinium dichromate (NDC) by Palomo et al.,379 was later shown by X-ray-crystal analysis380 to be a betainic mixed anhydride of nicotinic and chromic acid (NACAA). Because of its unique structure, it deserves a close scrutiny of its oxidative properties.381 Replacement of the chloride anion in the quaternary ammonium resin, Dowex 1-X8, for the dichromate anion, leads to a polymer supported dichromate, which is able to make selective benzylic oxidations.382 Finally, poly[vinyl(pyridinium dichromate)] (PVPDC), a polymeric analogue of PDC, must be mentioned whose use in the oxidation of alcohols allows for a very easy work-up.383... 

A mixture of molybdenum hexacarbonyl and 4-chlorophenol is effective in performing al-kyne metathesis of dipropynylated dialkylbenzenes. Alkyne metathesis of these precursors leads to the clean formation of dialkyl poly( paraphenyleneethynylene)s (PPEs) in high yield and with high molecular weights. This facile yet effective access to the PPEs has allowed study of their spectroscopic, structural, and thermal properties. While PPEs have been made before, the dialkyl-PPEs turned out to have particularly interesting optical and liquid-crystalline properties that can be explained in terms of the conformation of the main chains. The PPEs have also been utilized to construct light-emitting diodes and other semiconductor devices. This chapter discusses the interplay of structure, chromicity, and electronic properties of the dialkyl-PPEs. 

Pig. 7. Structure of photo-chromic poly(bisphenol-A-pimelate) (XI) (M = 13200) ... 

Prepn is by treating TNT in tetrahydrofuran with a mixt of methanol-KOH, and then with picryl chloride in the presence of Me2SO. The prod of this step is then oxidized with chromic oxide in a nitric acid—oleum mixt to yield the poly-nitrodiphenyl methane. The compd is expl Refs 1) Beil - not found 2)K.G.Shipp L.A. Kaplan, Substituted Polynitrodiphenylmethanes , USP 3941853 (1976) CA 84, 150325(1976)... 

Chromic hydroxide is an amphoteric compound and exhibits acidic properties in combining with basic oxides to form chromites, to which the general formula M-jO.CrjOg is given, and which are isomorphous with the corresiiouding aluminium compounds known as spinels. They may be considered as derived from an acid, HCrOj the monohydrate, CrjOj.HjO, has this empirical formula. From a study of the action of sodium hydroxide on chromium hydroxide for prolonged periods and the rate of the formation of chromate by the oxidation of dissolved chromite, it would appear that the chronlic hydroxide acts as a poly basic acid. 

The peak shift due to aggregation is observed not only in LBK films containing azobenzene chromophores, but also for other chromophores with extended Ji-systems, such as viologen polymers. For monolayers of the poly(p-phenylene sulfonate) 9/ dioctadecyldimethylammonium bromide (DODA) complex, the peak shift due to aggregation results in a piezo-chromic effect—that is, upon compression of the monolayer, a significant shift of the poly(p-phenylene sulfate) A band is observed (see Figure 6.9). This photochromic effect has been shown to be based on the improved 7t-Jt interaction upon compression of the monolayer. ... 

The structure analyses of two special types of dlacetylene "monomers," dlyne dimers and polydiyne macromonomers, are reviewed and preliminary results on the conversion and chromic behavior of one specific system, poly(l,8-nonadlyne) (F18N) are presented. Structure analyses of these materials before and after solid state polymerization allows a qualitative understanding of the dlacetylene polymerization. Cross-polymerized P18N has been shown to display solvatochromlc and thermochromlc behavior, even though this material Is Insoluble and Infusible. Examination of Initial optical spectroscopic data of the chromic behavior as a function of conversion, as well as consideration of the chromic behavior of conventional diacetylenes, leads to a possible explanation of the chromic behavior of crosspolymerlzed P18N. 

Crosspolymerlzed poly(l,8-nonadlyne) has been observed to show Interesting chromic behavior upon exposure to heat or certain solvents (4). Preliminary results on this chromic behavior have been Interpreted In terms of the structure of this material and the observed chromic behavior of other polydlacetylene systems. 

Polydlacetylenes are typically highly colored materials, and, consequently, there Is considerable Interest In their chromic behavior. In the case of poly(l,8 nonadlyne), chromic transitions can be Induced with heat or solvent treatment. The films used were cast from slowly evaporated methylene chloride solution. All UV exposures were performed as described earlier. 

High-density polyethylenes are formed from metal oxide initiation. These poly-ethylenes are stiffer, with much less branching. HDPE is used more in automotive applications due to this property. Phillips Petroleum uses a chromic oxide catalyst and Standard Oil of Indiana has developed a molybdenum oxide catalyst [5], These catalysts are not flammable, which presents an advantage over Ziegler-Natta. 

Spiropyran molecules have also been utilized as reverse wettable surfaces, whereby, a hydrophilic surface may be photomodulated to a hydrophobic surface and vice versa. Lygeraki et al. utilized the polar (mercocyanine, zwitterionic open-form) and nonpolar (spiropyran closed-form) properties of the spiropyran-merocyanine photo-chromic transformation to photomodulate surface wettability. 6-N02 BIPS (10 wt %) was added to a poly(methy 1 methacrylate) host matrix and patterned to produce reverse wettable surfaces. However, reversibility is limited to 6-8 irradiation cycles because of degradative photooxidation [22], Reverse wettable surfaces are commercially important as they may enhance drug delivery or function as a self-cleaning surface. 

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