Novel fluorescent light-emitting polymer composites bearing 1,2,4-triazole and quinoxaline moieties: Reinforcement and thermal stabilization with silicon carbide nanoparticles by epoxide functionalization

New diamines bearing substituted 1,2,4-triazole and quinoxaline moieties with OCH3 or Br units were successfully synthesized and used for preparation of novel polyamides (PAs) by direct polycondensation with aromatic and aliphatic dicarboxylic acids. Chemical structure of the diamines as well as the resulting polymers was confirmed by elemental analysis, FT-IR and 1H NMR spectroscopic methods. Inherent viscosities of these PAs were in the range of 0.52-0.56 dL/g, they were readily soluble in a variety of organic solvents and formed low-coloured and tough thin films via solution casting. The aromatic PAs exhibited Tg between 284 °C and 300 °C, and their 10% weight loss temperatures were in excess of 420 °C with up to 70% char yield at 600 °C in N2. These PAs emitted green or blue fluorescence in dilute NMP solution and in the solid state. Silicon carbide (SiC) nanoparticles modified by silane coupling agent were used to prepare SiC/PA particle-reinforced composites by solution blending. Thermal properties of nanocomposites by using DMTA, DSC and TGA and also solubility and optical properties were investigated. The results show that both the uniform particle dispersion and the strong chemical bonding between the nanoparticles and the polymer-matrix contributed to the enhanced Tg, storage modulus and thermal stability.