Soluble aromatic polyamides containing pendant pentadecyl substituted methoxy phenyl unit

Abstract

A new aromatic diamine 4-(3′,5′-diamino benzoyl amido)-3-pentadecyl anisole; (V) containing pendant pentadecyl substituted methoxyphenyl moiety was synthesized and characterized by FT-IR, NMR (¹H and ¹³C) and mass spectrometry. New aromatic polyamides were prepared from the diamine (V) and two aromatic diacid chlorides, Isophthaloyl chloride (IPC), Terphthaloyl chloride (TPC) using low temperature solution polycondensation method. Inherent viscosities of the polyamides were in the range 0.30 to 0.52 dL/g inN,N,Dimethylacetamide(DMAc) indicating moderate to high molecular weight of polyamides. The resulting polyamides were soluble in N-Methyl Pyrrolidone(NMP), N, N, Dimethyl formamide (DMF), N, N, Dimethyl acetamide (DMAc), N, N, Dimethyl sulphoxide(DMSO) and m-cresol. These polyamides showed relatively lower glass transition temperatures which were in the range 196-249 °C; Probably due to pendant alkyl substituted anisole structure which could impart internal plasticization effect. Thermal stability with T₁₀ weight loss temperature in the range of 359-387 °C under nitrogen atmosphere illustrated good thermal stability. XRD of all polyamides showed that polyamides are amorphous in morphology; which is well reflected in good solubility of these polyamides in polar aprotic solvents named above. Thus incorporation of pendant methoxyphenylunit with pentadecyl substituent brought improvement in their solubility and processable properties by lowering T_gvalues; without any significant deterioration of their thermal stability.