Solubility polyphenylenes

Polyphenylene polymers can be prepared by this coupling. For example, the preparation of poly(/i-quaterphenylene-2,2 -dicarboxylic acid) (643) was carried out using aqueous NaHCO and a water-soluble phosphine ligand (DPMSPP)[5I I]. Branched polyphenylene was also prepared[5l2). 

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

In 1968 the Monsanto Company announced the availability of novel soluble low molecular weight polyphenylene resins. These may be used to impregnate asbestos or carbon fibre and then cross-linked to produce heat-resistant laminates. The basic patent (BP 1037111) indicates that these resins are prepared by heating aromatic sulphonyl halides (e.g. benzene-1,3-disulphonyl dichloride) with aromatic compounds having replaceable nuclear hydrogen (e.g. bisphenoxy-benzenes, sexiphenyl and diphenyl ether). Copper halides are effective catalysts. The molecular weight is limited initially by a deficiency in one component. This is added later with further catalyst to cure the polymer. 

Kim and Webster of DuPont [61] were the first to show that trifunctional benzene-based monomers can also be used to synthesize polyphenylenes, in their case hyperbranched structures based on 1,3,5-trisubstituted benzene rings. They self-condensed l,3-dibromophenyl-5-boronic acid,to form soluble,hyperbranched PPP-type macromolecules, 47. 

A carboxylate derivative of a fully aromatic, water-soluble, hyperbranched polyphenylene is considered as a unimolecular micelle due to its ability to complex and solubilize non-polar guest molecules [23]. The carboxylic acid derivative of hyperbranched polyphenylene polymer (HBP) (My,=5750-7077, Mn=3810-3910) consists of 40-60 phenyl units that branch outward from a central point forming a roughly spherical molecule with carboxylates on the outer surface. The free acid form of HBP was suspended in distilled water and dissolved by adding a minimum quantity of NaOH. The solution was adjusted to pH 6.2 with aqueous HCl. Calcium carbonate crystals were growth from supersaturated calcium hydrogencarbonate solution at room temperature. HBP gave... 

S.H. Askari, S.D. Rughooputh, and F. Wudl, Soluble substituted-polyphenylene vinylene (PPV) conducting polymers spectroscopic studies, Synth. Met., 29 E129-E134, 1989. 

F. Wudl and H.M. Peters, Highly Soluble, Conductive, Luminescent Polyphenylene Vinylenes, and Products and Uses Thereof, PCT Patent Appl. WO 94/20589, September 15, 1994. 

F. Wudl and S. Hoger, Highly Organic Solvent Soluble, Water Insoluble Electroluminescent Polyphenylene Vinylenes having Pendant Steroid Group and Products and Uses Thereof, U.S. Patent 5,679,757, October 21, 1997. 

One of the first properties of hyperbranched polymers that was reported to differ from those of linear analogs was the high solubility induced by the branched backbone. Kim and Webster [31] reported that hyperbranched polyphenylenes had very good solubility in various solvents as compared to linear polyphenylenes, which have very poor solubility. The solubility depended to a large extent on the structure of the end groups, and thus highly polar end-groups such as carboxylates would make the polyphenylenes even water-soluble. 

Scheme 17. Water soluble second-generation polyphenylene dendrimer decorated with 16 car-boxy-functions... 

Kim YH, Webster OW. Water soluble hyperbranched polyphenylene a unimolecular micelle J Am Chem Soc 1990 112 4592-4593. 

Dealing with the same type of rigid-rod ionomers, Wallow and Novak recently prepared [44,45] a series of carboxy pendent polyphenylenes (XI). Using a Pd(o) water soluble catalyst, p-ordered polyphenylenes were prepared... 

The synthesis of soluble, fully aromatic-substituted polyphenylenes 19 has been pursued, as outlined in Scheme 24, where polymerization of various dihaloben-zenes was accomplished by initial activation with f-butyl lithium [88,89]. In this example, the use of 1.5 equivalents of f-butyl lithium in conjunction with dibro-mobenzene in THF at -78 °C, followed by warming to room temperature, yielded 19. 

Novel, hyper-branched polyphenylenes 20 have been prepared by the selfcoupling of 3,5-dibromophenylboronic acid in the presence of Pd(PPh3)4 as shown in Scheme 25 [90,91]. (The monomer was prepared by treatment of the monolithiate of 1,3,5-triboromobenzene with trimethyl borate.) The hyper-branched polymer was found to be organic soluble, and could be converted to a water-soluble, polyphenylene derivative by treatment with butyl lithium followed by quenching with C02. The water-soluble nature of such hyper-branched polyphenylenes has made them suitable candidates for use in various applications such as unimolecular micelles. 

It is important to note that the polyphenylene macromolecules are colorless and soluble in organic... 

Polyphenylene oxide Methanol Solvent degrease. Plastic is soluble in xylene and may be primed with adhesive in xylene solvent... 

Kambour et al. performed extensive studies on the mechanisms of plasticization [18-25]. The correlation observed between the critical strain to craze and the extent of the glass-transition temperature (Tg) depression speaks strongly in favor of a mechanism of easier chain motion and hence easier void formation. In various studies on polycarbonate [19,24], polyphenylene oxide [20], polysulfone [21], polystyrene [22], and polyetherimide [25], Kambour and coauthors showed that the absorption of solvent and accompanying reduction in the polymer s glass-transition temperature could be correlated with a propensity for stress cracking. The experiments, performed over a wide range of polymer-solvent systems, allowed Kambour to observe that the critical strain to craze or crack was least in those systems where the polymer and the solvent had similar solubility values. The Hildebrand solubility parameter S [26] is defined as... 

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