Biphenylene units

Figure 45 Synthesis of polymers with alternating binaphthylene and biphenylene units. (From Ref. 212.)...

In contrast, when a larger tetracationic cyclophane ring was employed in another set of experiments, the formation of new [3]-catenanes was found to be more facile. ° The expanded ring was obtained by replacing the phenylene linker units in the normal tetracationic cyclophane with biphenylene units. This larger ring was found to form readily around two threaded crowns when the latter are present in the acetonitrile reaction mixture in several-fold excess. Both bis-p-phenylene-34-crown-lO and l,5-dinaphtho-38-crown-10 were successfully employed in separate reactions to produce the corresponding [3]-catenanes in 20 and 31% yields, respectively. 

Polymers Containing Other Bridged Biphenylene Units... 

Depending on the modifications of poly-(p-phenylene terephthalamide) and analogous aromatic polyamides, it is possible to vary the solubility from concentrated sulfuric acid, to nonpolar aprotic solvents with inorganic salts, or to nonpolar aprotic solvents and to common organic colvents. In particular the incorporation of noncoplanar 2,2 -disubstitution has proven to remarkable enhance the solubility and lower the crystallinity. Gaudiana et al. [35] demonstrated that para-linked aromatic polyamides containing noncoplanar 2,2 -bis(trifluorome-thyl)biphenylene units are highly soluble in... 

In an essentially similar way as in the conventional process, copolymers with phenylene and biphenylene units separated by sulfide groups have been prepared. The biphenylene unit is made up from 4,4 -diflurobiphenyl or 4,4 -dibromobiphenyl and the phenylene unit is formed from p-dichlo-robenzene. Sodium acetate and sodium hydrogen sulfide are charged in an autoclave and NMP is used as a solvent. At the end of the heating period of 150 min up to 310°C, a pressure of around 25 bar develops in the autoclave. 

W. Grasser, H.-W. Schmidt, and R. Giesa. Fibers spun from poly(ethyl-ene terephthalate) blended with a thermotropic liquid crystalline copolyester with non-coplanar biphenylene units. Polymer, 42(21) 8517-8527, October 2001. 

We clarified the reason of the lower Tm of Me-HQ/BB than that of Me-HQ/TA by investigating the stability of liquid crystalline state of the model compounds derived from BB and TA as shown in Fig. l.The reason that Me-HQ/BB showed lower Tm is probably the lower enthalpy of Me-HQ/BB due to the twisted chemical structure of biphenylene unit as reported by K.Tashiro (4). ... 

The density of the injection molded test pieces of polyarylates derived from BB was low.The density of Me-HQ/BB/NDA(m/n=9.5/0.5) was 1.3. We assumed that the reason of the low density was the twisted structure of biphenylene unit(4). 

There are examples of poly(arylene ether)s, polyimides, and polyamides having l,l -binaphthy-lene-2,2 -diyl or biphenylene units that introduce chiral twists in the polymer chain. The chiral groups are expected to make the entire chain take a helical conformation. Earlier studies based on similar molecular designs are cited in Mi et... 

D.-J. Liaw, C.-C. Huang, W.-H. Chen, Color lightness and highly organosoluble fluorinated polyamides, polyimides and poly(amide-imide)s based on noncoplanar 2,2 -dimethyl-4,4 -biphenylene units. Polymer 47 (7) (2006) 2337-2348. 

In continuation of the development of the soluble polyamides, Liaw et al. synthesized fluorinated PAs based on noncoplanar 2,2 -dimethyl-4,4 -biphenylene units (Figure 4.10) [50]. The diamine monomer, 2,2 -dimethyl-4,4 fcis(2-trifluoromethyl-4-amino-phenoxy)biphenyl, was used in the preparation of a series of PAs. All these PAs exhibited excellent solubility in common amide solvents and were even soluble in solvents like cyclohexanone and y-butyrolactone at room temperature. The Tg values of the PAs were in the range of 230-265 °C. All these PAs showed high thermal stabihty, and the T io values were higher than 460 °C under nitrogen atmosphere. Rexible and tough membranes from all these PAs were obtained... 

Figure 4.10 Fluorinated polyamides prepared from noncoplanar2,2 -dimethyl-4,4 -biphenylene units [50],...

Miyatake et al. have combined two strategies in a single polymer architecture (multiblock copolymers containing sulfonic acid clusters in their hydrophilic blocks) [62]. They have successfully synthesized a series of multiblock poly (arylene ether sulfone ketone)s (SPESKs) containing fully sulfonated fluorenylidene biphenylene units (Fig. 7.23) [63, 64]. The well-controlled post-sulfonation reaction of the precursor polymers enabled preferential sulfonation on... 

Fig. 7.23 Multiblock poly(arylene ether sulfone ketone)s (SPESKs) containing fully sulfonated fluorenylidene biphenylene units...

The history of PEEK can be derived back to the s)mthesis of polyether ketone with the repeating unit stnicturie ofPh 0—Ph-CO-- (PEK) in 1960s. Broadly, polyetherketones can include a vast range of unit structures including ether, ketone and biphenylene units. However, the commercial PEKs consist of simple repeat units... 

Polyaromatic structures such as polyquinolines 12, that have the biphenylene units incorporated into the main chain, undergo crosslinking reac t ions. ... 

Polyquino1ines, polyamides, polyquinoxa1ines, and polybenzimidazoles, all containing biphenylene units, crosslink thermally, with or without the aid of transition metal catalysts. 

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