ORIGINAL PAPER Synthesis and degradation study of novel polyamides derived from a biologically active aromatic diacid monomer 5-(2-phthalimidoethanesulfonamido) isophthalic acid Mohammad Ali Karimi Zarchi & Mohammad Tayefi & Farhang Tirgir & Mohammad R. Sabzalian Received: 16 November 2011 / Accepted: 30 March 2012 / Published online: 4 May 2012 # Springer Science+Business Media B.V. 2012 Abstract In this study, 5-(2-phthalimidoethanesulfonamido) isophthalic acid (6) as a bioactive diacid monomer derived from taurine was successfully synthesized in three steps. The direct polycondensation reactions of this diacid monomer with several aromatic and aliphatic diisocyanates were carried out under conventional heating. All of the polyamides (PAs) were characterized by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance ( 1 H NMR) and elemental analy- ses methods. The thermal stability of the resulting PAs was evaluated with thermogravimetric analysis (TGA) and differ- ential scanning calorimetry (DSC) techniques under a nitro- gen atmosphere. The dehydrogenase activities of treated soils with obtained compounds were also studied. The results showed that the dehydrogenase activity of treated soils with obtained compounds was 2–3 times higher than control soil, indicating that the abundance and activity of the microbial communities in the treated soils were enhanced by the pres- ence of monomers and obtained polymers. This may show biodegradability of polymers under soil burial in natural environments and non-toxic behavior of compounds for soil microorganisms. Keywords Polyamide . Biodegradable . Taurine . Dehydrogenase enzyme . Aromatic diisocyanate Introduction Polyamides (PAs) are among the most important synthetic macromolecules. They are well known as a class of com- mercially important thermal stable polymers. They show excellent physical and chemical properties, and oxidative stability that make them practical as high performance mate- rials for advanced technologies [1–4]. Also PAs are useful biomaterials owing to their biodegradability and good me- chanical strength [5]. Polyamides may especially be very useful for medical purposes because of their biodegradabil- ity and safety [6]. They can be biodegraded in the natural environment. From these properties, PAs becomes a new attractive biodegradable material [7]. The ordering and changing of backbone functions have significant effects on the final properties such as thermal stability, solubility, and biodegradability characteristics of the macromolecules. Remaining to rigid backbones of PAs, they usually have high melting temperatures or Tgs and limited solubility in most polar organic solvents which make them limited regarding technological uses [8]. To get the better of these limitations, the modification of the macro- molecule structure is necessary. One of the general approaches for enhancing the solubility and process ability of PAs without forgo their thermal stability is the assimila- tion of bulky pendent groups into the polymer backbone. If the bulky pendent groups be carefully chosen in the way that M. A. Karimi Zarchi (*) : M. Tayefi Department of Chemistry, College of Science, Yazd University, P. O. Box 89195-741 Yazd, Iran e-mail: makarimi@yazduni.ac.ir F. Tirgir Department of Chemistry, Faculty of Science, Islamic Azad University, Shahrekord branch, Shahrekord, Iran M. R. Sabzalian College of Agriculture, Department of Agronomy and Plant Breeding, Isfahan University of Technology, Isfahan 84156-83111, Iran J Polym Res (2012) 19:9865 DOI 10.1007/s10965-012-9865-x