Synthesis of multitask star-shaped oligoaniline: Introducing a novel, efficient epoxy hardener

Multitask star-shaped oligoaniline (S-TAH) was synthesized using microwave irradiation in three steps: preparation of phthalic acid- capped tetra-aniline (as the arm), synthesis of a tetrafunctional biobased core, and subsequently, coupling arms to the core, using a divergent approach. A biobased core was synthesized through a direct condensation reaction of pentaerythritol, with l-lactic acid. The chemical structures were extensively characterized using Fourier-transform infrared and proton nuclear magnetic resonance spectroscopy. The performance of S-TAH, as a multitask hardener for bisphenol A-based epoxy resin (EP), was evaluated using differential scanning calorimetry, thermal gravimetric analysis, dynamic thermomechanical analyses (DMTA), and four-prob conductometry. Peaks of cure exotherms for S-TAH/EP (1:1) systems appear at 135? with a tail-like peak around 175 degrees C. Compared to conventional amine-cured EP, the thermal stability of the S-TAH/EP cured was significantly higher, that is, similar to 40 degrees C enhancement in half weight loss temperature (T-50). A three-fold improvement in char yield was observed. From DMTA, the material cured with S-TAH displays representative storage moduli in glassy (9.4 GPa) and rubbery (5.2 GPa) states reflecting a uniform network and viscoelastic behavior. The electrical conductivities (s) of the pure S-TAH and the epoxy systems cured with S-TAH/EP are 4.3 x 10(-4), and 2.65 x 10(-4), respectively. T star-shaped oligoaniline is a promising multitask hardener-functioning as hardener, thermal stabilizer, electrically conductive and toughening agents-which can be versatilely applied in thermal resistance anticorrosive coatings and conductive adhesives.

Automated summary

Multitask star-shaped oligoaniline (S-TAH), synthesized through a three-step microwave irradiation process, showed excellent performance as a multitask hardener for bisphenol A-based epoxy resin. It exhibited improved thermal stability, increased char yield, and representative storage moduli in glassy and rubbery states. Furthermore, it demonstrated good electrical conductivity and can be applied in various applications such as thermal resistance anticorrosive coatings and conductive adhesives.