Synthesis of aromatic poly(amide-imide)s from novel diimide-diacid (DIDA) containing sulphone and bulky pendant groups by direct polycondensation with various diamines Prashant S. Patil a , Ravindra R. Pal a , Manikrao M. Salunkhe a, * , Noormahamad N. Maldar b , Prakash P. Wadgaonkar c a Department of Chemistry, The Institute of Science, 15-Madam Cama Road, Mumbai 400 032, India b Department of Chemistry, Solapur University, Solapur 413 255, India c Polymer Chemistry Division, National Chemical Laboratory, Pune 411 008, India Received 21 April 2007; received in revised form 24 July 2007; accepted 28 August 2007 Available online 2 September 2007 Abstract A novel diimide-diacid (DIDA) monomer, 4-{4-[(4-methyl phenyl) sulphonyl]}-1,3-bis-trimellitoimido benzene contain- ing sulphone and bulky pendant groups was successfully synthesized and used to synthesize a series of wholly aromatic poly(amide-imide)s (PAIs) by direct polycondensation method. The direct polycondensation of newly synthesized DIDA with different diamines was carried out via Yamazaki’s phosphorylation method using triphenyl phosphite and pyridine system. The resulting poly(amide-imide)s were obtained in quantitative yields with inherent viscosities 0.36–0.47 dl/g in DMAc at 30 ± 0.1 °C. The poly(amide-imide)s were amorphous and were readily soluble in various solvents such as N- methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and pyridine. Tough and flexible films were obtained by casting their DMAc solution. According to thermo- gravimetric analysis, the polymers were fairly stable up to temperature around 396 °C, and 10% weight losses in the tem- perature range of 476–511 °C that showed good thermal stabilities of these polymers. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Poly(amide-imide)s; Sulphone and bulky pendant groups; Direct polycondensation; Thermally stable polymers 1. Introduction Aromatic polyimides are well known as high per- formance polymeric materials because of their excel- lent thermal stability, electric insulation properties and chemical resistance [1]. However, their applica- tions are limited because of their high softening, melting temperatures, and their insoluble nature in most organic solvents. The solubility of polyimides has been successfully improved by the incorporation of fluorine moieties [2a,2b] or chlorine moieties [2c], bulky side groups [2d] or pendant phenyl groups [2e] 0014-3057/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2007.08.016 * Corresponding author. Tel./fax: +91 22 22816750. E-mail address: mmsalunkhe@hotmail.com (M.M. Salu- nkhe). Available online at www.sciencedirect.com European Polymer Journal 43 (2007) 5047–5054 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL