Abstract
An unsymmetrical heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phenoxy)-naphthyl]-2-(4-carboxyphenyl) phthalazin-1-one (1) was successfully prepared. A series of polyamides containing phthalazinone were prepared from the prepared dicarboxylic acid with various aromatic diamines in an ionic liquid (IL) as a green, safe, and eco-friendly medium and also reactions catalysis agent. Evaluation of data shows that IL is the better polyamidation medium than the reported method and the catalysis stands on the higher inherent viscosities and yields of the obtained PAs and the rate of polymerizations beyond the greener reaction conditions and deletion of some essential reagents in conventional manner. Characterization was performed by means of 1H-NMR and FT-IR spectroscopy, elemental analysis, thermogravimetric analysis, and differential scanning calorimetric techniques. Molecular weights of the obtained polyamides were evaluated viscometrically, and the measured inherent viscosities were in the range of 0.46–0.71 dL/g. These polyamides were readily soluble in many organic solvents. These polymers still keep good thermal stability with high glass transition temperatures in the range of 310–345∘C and the decomposition temperature under the nitrogen atmosphere for 10% weight-loss temperatures in excess of 488∘C.
Highlights
Due to the increasing demands for high-performance polymers as a replacement for ceramics or metals in the microelectronic, aerospace and automotive industries, and thermally stable polymers have received much interest over the past decade
Ether linkages inserted in the main chains provide them with significantly lower energy of internal rotation. 1,2-dihydro-4-(4-hydroxyphenyl) (2H) phthalazinones as bisphenol-like monomers were introduced by Berard and Hay [13], and a number of polymers such as poly(phthalazinone ether)s, polyamides, polyimides, and polyesters have been developed from the series of monomer
As shown in Scheme 1, the phthalazinone-containing aromatic dicarboxylic acid was prepared by alkaline hydrolysis of the corresponding dinitrile compound resulting from the nucleophilic substitution reaction of 4-(4-hydroxynaphthalenyl) phthalazin-1-one with pchlorobenzonitrile
Summary
Due to the increasing demands for high-performance polymers as a replacement for ceramics or metals in the microelectronic, aerospace and automotive industries, and thermally stable polymers have received much interest over the past decade. Typical approaches have been employed to improve the processability of these polyimides including the incorporation of flexible links [7], bulky pendant or cardo groups [8], kinked or unsymmetrical structures [9], and spiroskeletons [10] into the polymer chain These modifications lower the melting temperature and lead to soluble and amorphous polymers. In the present paper the prepared dicarboxylic acid containing phthalazinone (DHPZ) moiety in the main chain [1] was directly polycondensed with various aromatic diamines in an ionic liquid medium to produce a series of organosoluble polyamides The properties of these polymers, such as solubility and thermal stability of these polymers are discussed
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