Biphenylene moiety

The authors also prepared other compounds, such as the phosphorane 123 with a seven-membered ring, and homologues of 122 in which X is replaced by a biphenylene moiety similar to that in 120. When X in 122 is replaced by CH2, XRD gives the bond lengths as PO = 1.617(4), PN = 1.887(6) A. The important geometrical modifications brought about by methylation of the N atom are thus revealed. 

In an effort to increase the processibility of polyquinolines, fluoromethylene groups have been successfully incorporated into the chain in place of Ar in the bis (ketomethylene) moiety (94). In fact, a small percentage of perfluorobutylene groups in the polyquinoline chain was sufficient to decrease the T significandy while still retaining other desired mechanical and thermal properties. Another approach was to prepare a series of oligomeric polyquinolines containing pendent biphenylenes and capped with either phenyl or biphenylene moieties (95). A representative list of different polyquinoline backbones and their properties appears in Table 3. 

The Tg curve declined gently as HBA content increased because the introduction of biphenylene moiety and carbonate linkage would effectively increase Tg. 

Solubilities. Rogers et al. (16-18) have prepared and reported on a large number of aromatic polyesters and polyamides containing the 2,2 -disubstituted 4,4 -biphenylene moiety. Some of the polymers were soluble in common solvents such as tetrahydrofuran and acetone, with solubility as high as 50% in one case. The solubilities of the amide monomers synthesized in this work are shown in Table I. These compounds exhibited virtually no solubility in common solvents such as acetone but displayed fairly high solubilities in several amide solvents, with and without added salts. Lyotropic liquid crystallinity was not observed although solubilities were as high as 40% (w/w) in some solvents. 

The resins may be more readily dyed or pigmented to achieve a desired coloration. A PAES type that contain the biphenylene moiety has a high glass transition temperature of 260°C, which is 35°C higher than that ofPES.24... 

M. Shibata, J. Cao, and R. Yosomiya. Synthesis and properties of the block copolymers of poly(ether ether ketone) and the poly(aryl ether sulfone) containing biphenylene moiety. Polymer, 38(12) 3103-3108, June 1997. 

Dimethyl-4,4 -bis(4-aminophenoxy)biphenyl has a non-coplanar disubstituted biphenylene moiety and flexible aryl units. The incorporation of the disubstituted biphenylene in a polymer chain will not change the rod-like structure of the polymer backbone but reduces the interchain interactions. The tendency to crystallize and the transition temperatures are lowered and the solubility is enhanced. ... 

Figure 4.21 Fluorinated polyamides containing biphenylene moiety [34].

Type-1 polyester is made up of 1, 4-biphenylene moieties with an approaximate heat-deflection temperature (HDT) of 300°C under a load of 18.6 kg/cm. The representative product is named as "Xydar". Type - 2 polyester is made up of 2, 6-naphthalene moiety with an approximate HDT of 210°C under a load of 18.6 kg/cm. The representative product name of type 2 is "Vectra". While Type-3 polyester is made up p-hydroxybenzoic acid (HBA) modified poly (ethylene terephthalate) i.e combination of moieties of HBA and PET usually with 70/30 proportion. The representative product name of type -3 is "Rodrun". 

Figure 8.22 Chemical stmcture of commercially available Ekonol copolyester containing 1,4 biphenylene moiety.

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