ABSTRACT:New aromatic polyimides containing a tetraphenylnaphthalene unit were synthesized from 1,4-bis(4-aminophenyl)-2,3-diphenylnaphthalene and various aromatic tetracarboxylic dianhydride by the conventional two-step procedure that included ring-opening polyaddition in a polar amide-type solvent and subsequent thermal cyclic dehydration. These polyimides had inherent viscosities of dl g-1 and some polyimides were readily soluble in a wide range of organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, pyridine and m-cresol on heating. The glass transition temperature of the polyimides ranged from 306 to 375°C, and 10% weight loss temperatures were in air. KEY WORDS High Temperature Polyimides I Soluble Polyimides I 1,4-Bis(4-aminophenyl)-2,3-diphenylnaphthalene I Thermal Behavior I Aromatic polyimides are characterized by high glass transition temperatures (Tg) along with high decomposition temperatures and good mechanical properties. The only one major drawback is that they are insoluble in organic solvents and unprocessable after conversion from the polyamic acid, the precursor of polyimide, to the polyimide form. Several attempts have been made to improve the solubility of polyimides while maintaining the excellent thermal and mechanical properties. 1 -9

Polysiloxanes such as poly-APS and poly-EPS were prepared by the hydrolytic polycondensation of 3-aminopropyl(trimethoxy)silane (APS) and 3-N-2-aminoethylaminopropyl(trimethoxy)silane (EPS) in the nitrogen stream, respectively. Poly-APS or poly-EPS was mixed with bisphenol-A diglycidyl ether (828EL) in methyl ethyl ketone or dichloromethane, and the mixture was subjected to heating to prepare transparent and homogeneous thin films. A coating film was prepared by spincoating on glass and heating to give a pencil hardness of 9H when equivalent mixing was achieved. This hardness value is greater than that obtained using ethylenediamine in place of poly-APS or poly-EPS. The three-point-bending test was applied to the bulk bodies to show a maximum Young's modulus of 199.1 MPa for poly-APS and 322.6 MPa for poly-EPS when equivalent mixing was achieved.

ABSTRACT:A new highly phenylated diamine, 1,4-bis(4-aminophenyl)-2,3-diphenylnaphthalene, was synthesized in two steps starting from 2,5-bis(4-nitrophenyl)-3,4-diphenylcyclopentadienone. New aromatic polyamides containing tetraphenylnaphthalene unit were prepared by low temperature solution polycondensation of this diamine with various aromatic dicarboxylic acid chlorides. These polyamides had inherent viscosities of0.45---0.82 dlg-1 . Polyamides with m-phenylene moiety and flexible connecting group were soluble in various organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone, but those with rigid symmetric structures were soluble in only hot N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The glass transition temperature of the polyamides ranged from 268 to 366°C, and the 10% weight loss temperatures were above soooc in air. KEY WORDSHigh Temperature Polymers I Soluble Aromatic Polyamides I 1,4-Bis(4-aminophenyl)-2,3-diphenylnaphthalene I Thermal Behavior I Aromatic polyamides are high thermal stability coupled with high crystallinity and hence high temperature application especially as fibers. 1 However, most wholly aromatic polyamides are difficult to fabricate because of low solubility and high melting temperature. Several attempts have been made to improve the solubility by modifying the structure without losing their good thermal stability. Aromatic polyamides having phenyl-pendant structures such as tetraphenylthiophene, 2 -5 tetraphenylfuran, 6 tetraphenylpyrrole, 7 tetraphenylethylene, 8 triphenylamine, 9 triphenylphosphine, 10 triphenylbenzene, 11 hexaphenylbenzene, 12 and tetraphenylquinquephenyl, 13 have high thermal stability and high solubility. We conducted the synthesis of a new diamine monomer, 1 ,4-bis( 4-aminophenyl)-2,3-diphenylnaphtalene and aromatic polyamides derived from it. This article deals with the synthesis and characterization of novel aromatic polyamides from this diamine and aromatic dicarboxylic acid chlorides. The properties of polyamides such as solubility and thermal behavior are also discussed.