Synthesis and Characterization of Novel Heat Resistance Poly(amide-imide)s from N,N 0 -[2,5-bis(4-aminobenzylidene) cyclopentanone] Bistrimellitimide Acid and Various Aromatic Diamines Mohsen Hajibeygi, 1 Khalil Faghihi, 2 Meisam Shabanian 3 1 Department of Chemistry, Varamin Pishva Branch, Islamic Azad University, Varamin Pishva, Iran 2 Polymer Research Laboratory, Department of Chemistry, Faculty of Science, Islamic Azad University, Arak Branch, Arak, Iran 3 Islamic Azad University, Arak Branch, Young Researchers Club, Arak, Iran Received 22 December 2009; accepted 1 December 2010 DOI 10.1002/app.33897 Published online 29 March 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: A new-type of dicarboxylic acid was syn- thesized from the reaction of 2,5-bis(4-aminobenzylidene)- cyclopentanone with trimellitic anhydride in a solution of glacial acetic acid/pyridine (Py) at refluxing temperature. Six novel heat resistance poly(amide-imide)s (PAIs) with good inherent viscosities were synthesized, from the direct polycondensation reaction of N,N 0 -[2,5-bis(4-aminobenzyli- dene)cyclopentanone]bistrimellitimide acid with several aromatic diamines, by two different methods such as direct polycondensation in a medium consisting of N- methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/ calcium chloride (CaCl 2 )/pyridine (Py) and direct poly- condensation in a p-toluene sulfonyl chloride (tosyl chlo- ride, TsCl)/pyridine (Py)/N,N-dimethylformamide (DMF) system. All of the above polymers were fully characterized by 1 H NMR, FTIR, elemental analysis, inherent viscosity, solubility tests, UV-vis spectroscopy, differential scan- ning calorimeter (DSC), thermogravimetric analysis (TGA), and derivative of thermaogravimetric (DTG). The resulted poly(amide-imide)s (PAIs) have showed admira- ble good inherent viscosities, thermal stability, and solubil- ity. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2877– 2885, 2011 Key words: heat resistance; poly(amide-imide); poly- condensation; trimellitic anhydride INTRODUCTION Polyimides and polyamide-imides are of high inter- est for many engineering applications due to their excellent thermal and mechanical properties. The aerospace, automobile, and microelectronics indus- tries have developed many important applications. 1 Additionally, introduction of alicyclic moieties into the main chains of polyimides restrains the forma- tion of intermolecular charge-transfer complexes to lower the dielectric constant, a property that is highly desirable for microelectronics applications. In addition to low dielectric constant, some excellent properties such as good optical clarity, low refractive index, and good mechanical properties are observed in mixed or fully nonaromatic polyimides. 2 However, the major limitation of polyimides for the versatile applications is their insolubility in com- mon organic solvents. In fact, unless carefully designed, polyimides are often insoluble in the fully imidized form. 3,4 Thus, their commercial applica- tions are limited in some fields. Therefore, prepara- tion of soluble polyimides without perceptible loss of favorable properties has been a major research in- terest, and a great deal of efforts has been made to improve the processing characteristics of this class of polymers. One of the successful approaches to improve solubility is the incorporation of other functional groups such as amide, 4–11 ester, 12,13 urethane, 14,15 and urea 16,17 linkages along the poly- mer skeleton. Aromatic poly(amide-imide)s possess desirable characteristics with the merits of both polyamides and polyimides, for example, high thermal stability and good mechanical properties as well as easy processability. Conventionally, aromatic poly(amide- imide)s can be prepared in several ways starting from trimellitic anhydride (TMA), such as two-step polycondensation from the acid chloride of TMA with aromatic diamines involving polyaddition and subsequent cyclodehydration, 18 low temperature so- lution polycondensation of TMA-derived imide ring- preformed diacid chloride and aromatic diamines, 19 polycondensation of TMA or TMA-derived imide ring-containing dicarboxylic acids with diisocya- nates, 20 and phosphorylation polyamidation between TMA-derived imide ring-performed dicarboxylic acids and aromatic diamines. 21 Correspondence to: K. Faghihi (k-faghihi@araku.ac.ir). Journal of Applied Polymer Science, Vol. 121, 2877–2885 (2011) V C 2011 Wiley Periodicals, Inc.