Polyamides enhanced solubility

These polymers possess enhanced solubility compared to the aromatic polyamides with no deterioration in thermal stability. Their Ts vary from... 

Jin and Kim reported the synthesis of polyamides coordinated to chromium tricarbonyl moieties (11) by condensation of (ii -phenylenediamine)Cr(CO)3 (12) with various diacid chlorides (13) (Scheme 2)7 It was noted that this polymer exhibited enhanced solubility due to incorporation of pendent chromium tricarbonyl moieties along its backbone. The viscosities of these polymers were determined in concentrated sulfuric acid or A(2/-dimethylacetamide containing 5% LiCl. The inherent viscosities of these metallated polymers ranged from 0.72 to 1.53 dL/g, and were found to be higher flian those of their organic analogs. 

Yet another type of polyamide nucleic acids analogs with a poly-L-lysine backbone (Fig. 20c, w = 4, z = 3) was described by Takemoto et al. (37). The ribose units in this analog mainly served the purpose of enhancing solubility of the polymers in water by the free hydroxy groups. For their preparation, 2 3 -0-isopropylidene-5 -0-glutaric acid succinimido nucleosides were coupled to prepolymerized L-lysine, a procedure not allowing sequence-specific introduction of nucleobases. 

The solubility of these dyes is significantly enhanced by introduction of alkenyl [35], hydroxypropyl [36], or polyetheralkyl [37] moieties into the trialkylammonium group. The trialkylammonium group may also be a component of a heterocyclic ring [38], When the trialkylammonium residue contains an alkyl chain of more than 11 carbon atoms, the dyes become soluble in aliphatic and alicyclic hydrocarbons and can be used for the production of printing inks [39], With aromatic diamines as the diazo components, such as 4,4 -diaminodiphenyl sulfone, basic disazo dyes are obtained which are suitable for dyeing acid-modified polyamide materials [40],... 

Microwave-assisted polycondensation reactions in ILs have also allowed the enhanced synthesis of polyamides and polyurethanes the comparison between microwave synthesis conditions in ILs with conventional heating methods and conventional organic solvents has also been addressed [92, 93]. Pretreatment methods combining microwave irradiation and ILs for cellulose dissolution and modification have been also proposed [94, 95]. Microwave irradiation can enhance the solubility of cellulose in ILs and decrease the degree of polymerization of regenerated cellulose after IL dissolution, which can be beneficial for improving cellulose hydrolysis [95]. 

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... 

The improvement in the solubility of the polyimides showed a similar tendency to that of the corresponding polyamides. For example, 2,5-di-f-butyl substituent in polymer backbone was too symmetrical for the solubility to be superior to that of /-butyl-substituted polymers From the solubility behaviors of the polyimides, therefore, it could be concluded that the incorporation of bulky pendant groups along the polymer chain gave the most effective enhancement in the solubility of polymers. (Fig. 2.8)... 

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