Polyaryl ether

Solvent for Displacement Reactions. As the most polar of the common aprotic solvents, DMSO is a favored solvent for displacement reactions because of its high dielectric constant and because anions are less solvated in it (87). Rates for these reactions are sometimes a thousand times faster in DMSO than in alcohols. Suitable nucleophiles include acetyUde ion, alkoxide ion, hydroxide ion, azide ion, carbanions, carboxylate ions, cyanide ion, hahde ions, mercaptide ions, phenoxide ions, nitrite ions, and thiocyanate ions (31). Rates of displacement by amides or amines are also greater in DMSO than in alcohol or aqueous solutions. Dimethyl sulfoxide is used as the reaction solvent in the manufacture of high performance, polyaryl ether polymers by reaction of bis(4,4 -chlorophenyl) sulfone with the disodium salts of dihydroxyphenols, eg, bisphenol A or 4,4 -sulfonylbisphenol (88). These and related reactions are made more economical by efficient recycling of DMSO (89). Nucleophilic displacement of activated aromatic nitro groups with aryloxy anion in DMSO is a versatile and useful reaction for the synthesis of aromatic ethers and polyethers (90). 

The polyaryl ether ketones quickly became established as outstanding heat-... 

Polyaryl ether ketones may be processed on conventional injection moulding and extrusion equipment, providing sufficiently high temperatures can be achieved. Melt temperatures required are typically 370°C for unreinforced PEEK, 390°C for reinforced PEEK and both unreinforced and reinforced PEK and unreinforced PEEKK, and 410°C for reinforced PEEKK. For the latter material a temperature profile from feed zone to nozzle would be... 

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. 

STYRENE-ACRYLONITILE AMINOPLASTICS POLYARYL ETHER POLYARYL SULFONE... 

In their efforts to construct stimuli-responsive, supramolecular amphiphiles, Frechet et al. [126-129] reported the synthesis of a novel series of AB and ABA block copolymers via the Williamson ether synthesis (e.g., 47, Fig. 21). Polyethylene glycols (PEGs) of different lengths were used as the linear hydrophilic B block while polyaryl ether dendrons of different sizes were used as the hydro-phobic A block. These copolymers were characterized by optical microscopy,... 

We initiated our work by examining nucleophilic aromatic substitution, a somewhat difficult reaction to effect in other than activated aryl halides as substrates. It occurred to us that if polyhaloaromatics could be made to suffer disubstitution under mild solid-liquid PTC conditions, then they might be used as comonomers with a variety of bisnucliophiles to prepare halogenated polyaryl-ethers, sulfides, sulfone-ethers as well as other interesting polymers which are at present synthesized only with some difficulty. 

The broad applicability of ATRP in the ionic liquid [BMIMjPFg was shown by extending it to the polymerization of N-substituted maleimides with styrene. The ATRP was initiated with dendritic polyaryl ether 2-bromoisobutyrate as the initiator at room temperature. The dendritic-linear block copolymers formed in the ionic liquid were characterized by low polydispersity (1.05chain-extension polymerization, suggesting the living nature of the polymerization 247). 

This type of Au NCDs can also be obtained using similar Frechet-type polyaryl ether dendritic disulfide wedges from generations 1 to 5 by the reduction of HAuCfi phase-transferred into toluene in the presence of the dendrons. analysis shows that the NCDs are small (2.01-3.93 nm) and not very monodisperse [130]. 

Dendritic analogues of engineering plastics-A general one-step synthesis of dendritic polyaryl ethers [T. M. Miller, T. X. Neenan, E. W. Kwock, S. M. Stein, Macromol. Symp. 1994, 77, 35-49]. 

Various kinds of engineering thermoplastics such as polyether sulfone, polyether imide, polyaryl ether ketone, and polyphenylene oxide have been studied as toughening agents for... 

Synthesis. Five different polyaryl ethers were made from the condensation product, resulting from the reaction of phenol and levulinic acid, commonly referred to as diphenolic acid, and one or more of the following monomers bisphenol A, dichlorodiphenyl sulfone, 2,6-dichloro-benzonitrile, and 4,4 -difluorobenzophenone. The resulting polymers were subsequently methylated such that the common monomer becomes (1) ... 

Six more polyaryl ethers were made from 2,6-dichlorobenzonitrile (2) and one of the following monomers l,l -bis(4-hydroxy-3,5-dimethyl phenyl) cyclohexane 2,2 -bis (4-hydroxyphenyl) -2-phenyl ethane 1,3-bis(4-hydroxyphenyl)-1-ethyl cyclohexane 2- ( hydroxyphenyl)-2-[3-(4-hydroxyphenyl) -4-methyl cyclohexyl ] propane 2,2 -bis (4-hydroxy-3,5-dimethyl phenyl) propane and bisphenol A. 

Polyaryl(ether-ketone-carbaborane)s have also been synthesized by using CF3SO3H as both solvent and catalyst to give linear amorphous polymers [Eq. (54)] [163]. These polymers have low molecular weights (IV = 0.24-0.59) and low thermolytic weight loss upon pyrolysis (10-15% at 1000° C)... 

Shen, L., Shi, M., Li, F.Y., et al. (2006) Polyaryl ether dendrimer with a 4-phenylacetyl-5-pyrazolone-based terbium(III) complex as core synthesis and photophysical properties. Inorganic Chemistry, 45, 6188-6197. 

Fullerene has also been incorporated in redox-active dendrimers. In 62 the Ceo unit has been modified by connecting a single polyaryl-ether dendritic branch [132]. Electrochemical reduction in CH2CI2 of 62 features three reversible waves, which occur at a potential more negative than that of the free Cso molecule. This shift was ascribed to an insulating effect on the connected dendritic structure. 

Oxidative coupling of phenols to polyaryl ethers is now a well-established commercial process. The reactions are complex, and anomalous kinetic features have been encountered. These have been discussed recently by Vollmert and Saatweber [213]. 

The first polymer with a flexible backbone was synthesized by a process known in the literature for making bisphenol A polyaryl ether under phase transfer catalysis conditions. We used this procedure to couple BPC with l,4-dichloro-2-butene (DCB) or 1,5-dibromopentane in ort/io-dichlorobenzene (o-DCB) to yield polyethers 7 and 8 (Fig. 12). 

Carbon-13 dynamic MAS NMR is used to determine the 7c-flip rates of the phenyl rings in the low-molecular-weight members of the polyaryl ethers series (phenyl-0(-phenylene-0)(n)-phenyl). ... 

Several polyaryl ether ketones, generically given the abbreviation PAEK, have been reported in the literature, including those shown in Table 21.5. Of these, three have been in commercial production. They are ... 

Fluorine-promoted stepwise polymerization of 4-fluorophenol derivative (23) provides a polyaryl ether (26) [7] where the fluorine atom plays an essential role in the activation of the reactive site in the chain extension step (Scheme 2.4). 

Poly(ethylene oxide) (PEO) has been employed frequently as a water-soluble catalyst support [9]. Further water-soluble polymers investigated include other linear polymers such as poly(acrylic acid) [10], poly(N-alkylacrylamide)s [11], and copolymers of maleic anhydride and methylvinylether [12], as well as dendritic materials such as poly(ethyleneimin) [10a, c] or PEO derivatives of polyaryl ethers [13]. The term dendritic refers to a highly branched, tree-like structure and includes perfectly branched dendrimers as well as statistically branched, hyperbranched macromolecules. 

For phosphorescence, lanthanide metal ions can be used in a similar manner. Lanthanide ions have very interesting photophysical properties, but often exhibit weak absorption bands, and aggregate to form clusters, which limit their applications. Thus, a dendrimer that can provide a protective shell to isolate a cation and at the same time enhance the emission by transfer from the periphery to the lanthanide ion at the core could be of great interest. Self-assembled lanthanide-cored dendrimers have been prepared to prove such an assumption synthesis was carried out by mixing three equivalents of polyaryl ether dendrons bearing carboxylic acid entity at the focal point with Ln(III) cations [Er(III), Tb(III), and Eu(III)] (Fig. 5.4) [34]. The authors demonstrated that the enhancement of the lanthanide cation emission associated with the dendritic core shell was observed, and an antenna effect from the periphery to the core was shown to promote this process. 

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