A series of new bio‐based aromatic diisocyanates, namely bis(4‐isocyanato‐2‐methoxyphenoxy)alkane and bis(4‐isocyanato‐2,6‐dimethoxyphenoxy)alkane, were synthesized starting from lignin‐derived phenolic acids, namely vanillic acid and syringic acid, via the Curtius rearrangement. The diisocyanates were employed to synthesize poly(ether urethane)s by reacting them with potentially bio‐based aliphatic diols, namely 1,10‐decanediol and 1,12‐dodecanediol. The chemical structures of diisocyanates and poly(ether urethane)s were confirmed using Fourier transform infrared, 1H NMR and 13C NMR spectroscopy. Inherent viscosities and number‐average molecular weights of the poly(ether urethane)s were in the ranges 0.58–0.68 dL g−1 and 32 100–58 500 g mol−1, respectively, indicating the formation of reasonably high molecular weight polymers. The poly(ether urethane)s exhibited 10% weight loss in the temperature range 304–308 °C. The glass transition temperatures of the poly(ether urethane)s were in the range 49–74 °C and were dependent both on the number of methylene units in the diols and on the number of methoxy substituents on the aromatic rings of the diisocyanate component. © 2017 Society of Chemical Industry

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Two new bio-based diacylhydrazide monomers, namely, 4,4 0 -(propane-1,3-diylbis(oxy))bis(3-methoxybenzohydrazide) and 4,4 0 -(propane-1,3-diylbis(oxy))bis(3,5-dimethoxybenzohydrazide) were synthesized starting from lignin-derived phenolic acids, namely, vanillic acid and syringic acid. A series of poly(amide imide)s was synthesized by polycondensation of these diacylhydrazide monomers with commercially available aromatic dianhydrides. Poly(amide imide)s showed inherent viscosity in the range 0.44-0.56 dL g 21 and exhibited good solubility in organic solvents. Poly(amide imide)s could be cast into transparent, flexible, and tough films from their N,N-dimethylacetamide solutions. Poly(amide imide)s showed 10% weight loss in the temperature range 340-364 8C indicating their good thermal stability. Glass transition temperature (T g ) of poly(amide imides)s were measured by DSC and DMA which were in the range 201-223 8C and 214-248 8C, respectively. The T g values of poly(amide imide)s were dependent on the number methoxy substituents on aromatic rings of diacylhydrazide monomers. Molecular dynamics simulation studies revealed that chain rigidity is the dominant factor for observed trends in T g . V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3636-3645 The presence of functional groups in these aromatic chemicals offers interesting possibilities to use them as precursors for synthesis of useful monomers. Thus, a range bio-based monomers and polymers have been synthesized from lignin-derived aromatics, 14,25 which include (meth)acrylic polymers, 26 epoxy polymers, 27 polybenzoxazines, 28 cyanate ester resins, 29 polycarbonates, 30 polyesters, 31-34 poly(ether ester)s, 14,35 polyacetals, 36 polyurethanes, 37,38 and so forth.Aromatic poly(amide imide)s represent an important class of high performance polymers due to their excellent thermal and mechanical properties. 12,[39][40][41] The excellent properties of poly(amide imide)s are derived from their distinctive chemical structure, which combine both amide and imide Additional Supporting Information may be found in the online version of this article.