Metaphenylenes

Figure 2. Solid-state spectra of four different epoxies (hosed on the resin diglycidyl ether of bisphenol-A) are compared with the liquid-state spectra of their respective unreacted components, The chemical compositions are in Table I. Here the epoxies are identified by their main curing agent (a) PIP—piperidine (b) MPDA—metaphenylene diamine (c) HHPA—hexahydro-phthalic anhydride (d) NMA—nadic methyl anhydride.

Low-valent palladium complex, for example, Pd(0), is readily prepared in situ by reaction of PdCl2(PPh3)2/Zn. This is shown to induce the similar homocoupling polycondensation of metaphenylene 183 at 95 °C in DMF. Fluorinated alkyl esters 180 polymerize smoothly in supercritical CO2 1,4-dichlorophenylene 184 having a keto group also reductively polymerized similarly. 

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 ... 

Metaphenylene diamine (MPDA) is one of the most common of the aromatic amines used to cure epoxies. This product is amber to very dark in color. It is a solid that melts at 65°C and is generally mixed with the epoxy resin at that temperature. The molten liquid or vapors from MPDA can stain the skin and nearby structures rather badly. The para-isomer is reported to be carcinogenic, but the meta-isomer is free from this disadvantage. 

Epoxy adhesives are generally more resistant to a wide variety of liquid environments than other structural adhesives. However, the resistance to a specific environment is greatly dependent on the type of epoxy curing agent used. Aromatic amine (e.g., metaphenylene diamine) cured systems are frequently preferred for long-term chemical resistance. 

Older epoxy resins were noticed to cause skin cancer in laboratory animals. This was most likely due to the epichlorohydrin. Most newer epoxy resins, which contain less epichlorohydrin, do not seem to cause cancer in animals. Certain curing agents, such as metaphenylene diamine (MPDA) and diaminodiphenyl sulfone (DADPS), and certain gly-cidyl ethers are carcinogenic in laboratory animals. It is not known if these materials cause cancer in humans. 

Lime gives a vdute turbidity on addition of saturated ammonium oxalate solution, and sulphates with barium chloride acidified with hydrochloric acid. A useful reagent for nitrites is metaphenylene diamine, 5 grams of which are dissolved in water, acidified with dilute sulphuric acid, and made up to one litre. It may be necessary to previously decolorise the solution with charcoal. If nitrites are present in the water to be tested, on addition of the diamine, a yellow colour is produced, either immediately or upon standing. Starch-iodide solution acidified with dilute sulphuric acid may also be used, the characteristic blue colour of the starch-iodine complex indicating nitrites, but this test is not altogether satisfactory. 

Dai, " and coworkers, and others.Nanotubes have been known to adsorb gas molecules (H2, N2, O2, and H2O) through adsorption. " Some polymers have strong noncovalent interactions with the carbon nanotubes. High molecular weight ionic or electron-rich polymers coat or wrap themselves around the carbon nanotubes. Polyvinyl pyrrolidone and polystyrene sulfonate and their copolymers, polyvinyl sulfate, and poly (metaphenylene vinylene) have been used to wrap around The wrapping... 

Bis-metaphenylene-32-crown-lO (10) (Structure 4) also forms complexes with the cations mentioned above [29]. 

Poly(metaphenylene isophthalamide) (Nomex high temperature resistant fibre) 126-135 50 14-17 1-38... 

Lu et al. [2] fabricated TFC NF membranes, in which the skin layer was either polyesters or polyamides. The monomers used in the polycondensation reactions are as follows (1) alcohol (bisphenol-A, BPA), (2) amine (metaphenylene diamine and piperazine), and (3) acid chloride (isophthaloyl chloride, terephthaloyl chloride [3,4], and trimesoyl chloride). They reported that the composite layer (active layer) was smoother than that of the substrate membrane. Upon formation of the active layer, the pore size decreased, which resulted in a flux decrease and a retention increase. Although it is unclear, they seem to maintain that their results confirm Hirose et al.s conclusion, i.e., the flux increases with an increase in surface roughness [Ij. 

Aromatic Epoxies cured with aromatic amines usually Metaphenylene... 

Aromatic amines are solids at room temperature and are routinely melted at elevated temperatures and blended with warmed resin. Eutectic mixtures of metaphenylene and methylene dianiline exhibit a depressed melting point, producing an aromatic hardener that remains liquid over short periods of time. Pot life is considerably longer that that of aliphatic polyamines. Cure at elevated temperature is needed to develop optimum properties, which are maintained at up to 15()°C. Aromatic amines have better chemical and thermal resistance than aliphatic polyamines. 

Figure 12.14. Poly(metaphenylene carbene). CAn yield a two-dimensional honeycomb system, where neighbouring loops may favour ferromagnetism (adapted from reference [198]).

Poylphenylenes were originally developed by Maxdem in California and subsequently by Mississippi Polymer Technologies (MPT). More recently MPT was bought by Solvay and the product is now sold under the trade name of Primospire. A pure paraphenylene would lack processability and so has to be substituted with phenylketone and/or copolymerised with unsubstituted metaphenylene [4-6]. In this way it is possible to produce both extrusion and injection... 

Fig. 18 Activation energy of p-relaxation in (a) low-molecular weight glasses and (b) linear polymers vs the cohesion energy or cohesion energy of Kuhn statistical segment, respectively [86, 88,103]. (a) (1) Pentanol (2) isopropylbenzene (3) 5-methyl-3-heptanol (4) decalin (5) 1,1-diphenylpropane (6) diethyl phthalate (7) glycerol (8) 6>-terphenyl (9) hexamethyl disolox-ane (10) tetra-a-methylstyrene (11) pentastyrene. (b) (1) Polyethylene (2) polyisoprene (3) poly(dimethylsiloxane) (4) poly(diethylsiloxane) (5) poly(phenylene oxide) (6) poly(ethylene terephthalate) (7) polytetrafluoroethylene (8) polycarbonate (9) polyamide (10) polypropylene (11) polymethacrylate (12) poly(vinyl fluoride) (13) poly(vinyl acetate) (14) poly(vinyl chloride) (15) poly(vinyl alcohol) (16) poly(methyl methacrylate) (17) poly(diphenyl oxypheny-lene) (18) poly(butyl methacrylate) (19) polystyrene (20) polyacrylonitrile (21) poly(a-methylstyrene) (22) poly(cyclohexyl methacrylate) (23) polyimide I (24) polyimide II (25) poly(metaphenylene isophthalamide) (26) polyisobutylene...

One of the most commonly used aromatic amines is metaphenylene diamine (MPDA), a solid with a melting point around 63" C... 

Such combinations often allow solubility in relatively non-polar solvents to be achieved. The shelf-life of a polyimide is also very dependent upon the constituent diamine and anhydride used. Polyimides derived from bis(4-amino phenyl)thioether are stable for several months in boiling water whilst those derived from metaphenylene and paraphenylene diamines rapidly become brittle under the same conditions. Some typically used amines are... 

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