Paraphenylenes

Stabilization of Fuels and Lubricants. Gasoline and jet engine fuels contain unsaturated compounds that oxidize on storage, darken, and form gums and deposits. Radical scavengers such as 2,4-dimethyl-6-/ f2 butylphenol [1879-09-0] 2,6-di-/ f2 -butyl-/)-cresol (1), 2,6-di-/ f2 -butylphenol [128-39-2], and alkylated paraphenylene diamines ate used in concentrations of about 5—10 ppm as stabilizers. 

Paraphenylene-diamine derivatives A/,N -Diphenyl-p-phenylenediamine (IV) /V,A/ -Di-p-naphthyl-p-phenylenediamine (V) Yes Yes Powerful antioxidants. Have been used in a variety of plastics materials. Tendency to bloom, bleed and stain mitigates against more extensive use. Compound (V) now withdrawn by some suppliers. 

Studies of the reaction rates of various substituted paraphenylene diamines (PPDAs) towards ozone show that their reactivities are directly related to the electron density on the nitrogens due to the different substituents. Reactivity decreases in the following order 7/,7/,7/, M-tetraalkyl > 7/,A, M-trialkyl > A,A -dialkyl > A -alkyl-M-aryl > -diaryl [61]. It should be noted that their ease of... 

Figure III.2 Product sheet of the aromatic amine N-, 3-dimethylbutyl-/V -phenyl-paraphenylene-diamine. After Gijsman [1], Reproduced by permission of P. Gijsman...

Both theoretical and experimental evidence suggest that the precise nature of the charge carriers in conjugated polymer systems varies from material to material, and it is still a subject of debate in many cases. A discussion of the various theoretical models for the electronic structure of conjugated polymers is given below, using polyacetylene and poly(paraphenylene) as examples. More detailed information on these materials and the applicability of these theoretical models is given in subsequent sections. 

Fig. 16. Cyclic voltammogram of poly(paraphenylene) PPP in CH3CN-0.2 M LiC104 using PVF + C paste on 0.2 sq. cm Pt electrode. Reproduced from ref. 224, by kind permission of Gordon and Breach Science Publishers S.A.

Y Yang, Q Pei, and AJ Heeger, Efficient blue polymer light-emitting diodes from a series of soluble poly(paraphenylene)s, J. Appl. Phys., 79 934—939, 1996. 

Interpretation/Results The colored component of the bad DA monomer is identified by LC-IR as N,N-dimethyl paraphenylene diamine. 

High adhesive polyimide films were prepared by Kaneshiro et al. (2) consisting of 2,2-bisaminophenoxylphenylpropane and paraphenylene diamine, pyro-mellitic dianhydride, and 3,3, 4,4 -benzophenone tetracarboxylic dianhydride. 

As ligands, phosphanes have proven to be useful (Table 7, No. 2-4). Poly(l,4-paraphenylene) is obtained on a preparative scale starting from aromatic dihalides (Table 7, No. 3, 4). The electrochemical generation and... 

PB. Sulekha, R. Joseph, and K.E. George, Studies on polyisobutylene bound paraphenylene diamine antioxidant in natural rubber, Polym. Degrad. Stab., 63(2) 225-230, February 1999. 

Methylene blue, new methylene blue, thionine blue, Capri blue, cresyl blue, brilliant cresyl blue, Nile blue, Basle blue, Mel-dola s blue, fast navy blue, new blue, metamine blue, naphthol u, blue, metaphenylene blue, paraphenylene blue, mdamine blue, indazine, neutral blue, muscanne, diphene blue, rhoduline blue, rhoduline sky blue frl ... 

Paraphenylene violet, rhoduline violet, rhoduline heliotrope, methylene violet, methylene hehotrope, tannin heliotrope, ins violet, amethyst violet, cresyl fast violet fit < > 0 ... 

Two natural extensions of this work are currently in progress first, it, is possible, in some extents, to improve the simple ansatz (26) by including more local configurations [42] second, it is also possible to apply the method to other conjugated polymers of current interests as the poly-paraphenylene and the poly-paraphenylenevinylene. 

PPDI PPG Prepolymer Processability initiating agent. An abbreviation for paraphenylene diisocyanate. Polypropylene glycol. The product from reacting a polyol with an isocyanate. The relative ease with which a raw or compounded polymer can be handled. 

Some of the structures reported from this laboratory for making CMEs for electrocatalytic oxidation of NADH are summarized in Figure 5. We have found that a positively charged paraphenylene-diimine is the best basic catalytic structure (55,83,84-87,89,91,92). When it is incorporated as a part of a phenoxazine or a phenothiazine (see Figure 5) some very beneficial properties are added to the mediator. The E° values are decreased with some 300 to 400 mV compared with the free paraphenylenediimine structure (57,58,102) and they strongly adsorb on graphite electrodes to form CMEs allowing NADH to be electrocatalytically oxidized well below 0 mV (55,83,84-87,89,91,92). 

Synthesis of more densely covered poly(paraphenylene) has also been attempted with two other monomers ... 

The most successful substitution reaction is via the isocyanate route. The poly (paraphenylene) backbone polymer chosen for this work... 

Abbreviations BSA, bovine serum albumin Chi, chlorophyll DCPIP, 2, 6-dichlorophenol indophenol DMBQ, 2, 6-dimethyl-l, 4-benzoquinone DTT, dithiothreitol Fd, ferredoxin Hepes, N-2-hydroxyethyl-piperazine N -2-ethane sulphonate LDAO, lauryldimethyl amine oxide Mes, 4-morpholine ethane sulphonic acid MV, methyl viologen PAGE, polyacrylamide gel electrophoresis PRuK, phosphoribulokinase PS, photosystem Ru5P, ribulose 5-phosphate SDS, sodium dodecyl sulphate TMPD, N, N, N, N -tetramethyl paraphenylene diamine TRX. thioredoxin... 

The polymeric phenolic phosphites (PPP) are reaction products of substituted hydroquinones and phosphorus trihalides such as phosphorus trichloride. They may be represented by the structure shown at the top of p. 213, where (A) represents subsituent groups on the paraphenylene portion of the hydroquinone. 

Whenever a new high strength fiber is developed, its potential for tire cord use is always explored because of the commercial attraction of large volumes available in the tire market. Few materials have emeiged to displace the current two major fibers, nylon and polyester (14). Nonetheless, many examples of fibers offering attractive properties for tire cords have been reported in the literature, eg, polyethylene ketone (17), poly(paraphenylene benzobisoxazole) (18), acrylics (19), and high strength poly (vinyl alcohol) (20) (see Vinyl polymers). 

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