Synthesis and thermal properties of soluble silicon containing phenylated aromatic–aliphatic polyamides A. A. Ghanwat Æ M. M. Sayyed Æ P. P. Wadgaonkar Æ N. N. Maldar Received: 4 November 2008 / Accepted: 5 February 2009 / Published online: 1 September 2009 Ó Akade ´miai Kiado ´, Budapest, Hungary 2009 Abstract Aromatic polyamides find many applications in diverse and critical areas due to their high thermal stability coupled with high mechanical properties. However most of such aramides are difficult to fabricate because of their limited solubility and high melting temperature. Improve- ments in processability have been reported by incorporat- ing bulky pendant groups and aliphatic spacer groups. Similarly to improve the solubility of polymers approaches of incorporating silicon in main polymer chain and co- polymerization techniques were useful. We report the synthesis and characterization of a series of phenylated silicon containing aromatic–aliphatic polyamides from a mixture of 2, 5-bis (4-carboxy methylene phenyl)-3, 4- diphenyl thiophene (CMPDT) and bis-(4-carboxy phenyl) dimethyl silane (BCPDS) in various mole proportions, with commercial aromatic diamine. Thus a series of novel co- polyamides having pendant phenyl groups, methylene spacer and silicon moiety was prepared by judicious combination of (CMPDT); BCPDS and aromatic diamine; bis-(4-aminophenyl) ether (ODA), by direct polyconden- sation using Yamazaki’s phosphorylation method. These high molecular mass polyamides were obtained in high (89–98%) yields and had viscosities in the range of 0.23– 0.57 dL/g in DMAc. Polyamides showed improved solu- bility in polar aprotic solvents, like NMP, DMAc, DMSO and DMF; had high thermal stability; with no mass loss below 335 °C. Keywords 2, 5-bis (4-carboxy methylene phenyl)-3, 4-diphenyl thiophene Á bis-(4-carboxy phenyl) dimethyl silane Á bis-(4-amino phenyl) ether Á Copolyamides Á Solubility Á Thermal stability Introduction Aromatic polyimides, polyamides have the poor process- ability due to their insolubility in common organic solvents and extremely high glass transition or melt temperature. The synthesis of soluble polyimides/polyamides without deteri- orating their excellent properties [1–6] include the prepara- tion of copolymers, introduction of bulky pendant groups, flexible linkages and kinked or unsymmetrical structures or cardo moiety into the polymer backbone. DSC studies of some polyamides [7, 8] were reported in literature. We successfully prepared aromatic polyamides [9], polyimides, poly (amide–imide)s, polybenzimidazoles [10], polyesters, polyquinoxalines, from a number of new cardo/methylene containing and phenylated functional monomers. Thermal behaviour of silicon containing poly(ester-imide)s [11] showed good thermal stability. Some aramides with silicon moieties in the backbone have been reported in the literature [12–15] however they were prepared from bis-(4-carboxy phenyl) dimethyl silane (BCPDS) or from bis [(4-carboxy phenyl) 4-benzamide] dimethyl silane, BCPBDS; with aro- matic diamines. These aromatic polyamides contained ‘Si’ but no methylene spacer in combination with phenylated thiophene moiety. Thus, there are no reports on phenylated methylene spacer and silicon containing polyamides. Therefore it was worth to synthesize copolyamides which have all structural units namely pendant phenyl, methylene spacer, silicon moiety and ether linkages; to study their overall effects on resulting polyamides. A. A. Ghanwat Á M. M. Sayyed Á N. N. Maldar (&) Department of Chemistry, Solapur University, Kegaon, Solapur 413255, India e-mail: maldar_nn@rediffmail.com P. P. Wadgaonkar Division of Polymer Science and Engineering, National Chemical Laboratory, Pune 411008, India 123 J Therm Anal Calorim (2009) 98:539–545 DOI 10.1007/s10973-009-0286-y