Carboxyl-Functionalized Polyarylethernitriles:Synthesis,Adsorption Of Heavy Metals And Fluorescence Property Of Rare Earth Complexes

Poly(arylene ether nitrile)s have been reported as a well known class of engineering thermoplastics, which have good thermooxidative stability, chemical resistance, high glass transition temperature, and excellent mechanical strengths. Owing to these outstanding properties, PAENs are widely used in transportation, aerospace, electrical, and electronic fields etc. But PAENs are insoluble in common organic solvents at room temperature, making it difficult to process. The introduction of twisted bisphenol structure was effective method to improve the solubility of PAEN without damage to module or thermal stability. Additionally, the existences of carboxyl groups in backbones made PAEN functionalized. We converted carboxylic functions (COOH) to carboxylate form (COO-Na+) and used it as adsorbent to remove heavy metal ions from aqueous solutions. Based on the fact that lanthanide can easily coordinate to oxygen, we used carboxyl groups as coordination site and prepared a series of novel rare earth functional polymeric materials with excellent fluorescent properties. Main contents and conclusions are as follows:(1) Three carboxyl-containing and soluble poly(arylene ether nitrile)s were obtained via solution nucleophilic polycondensation reaction with2,6-difluorobenzonitrile(DFBN) and phenolphthalin with different alkyl substitutents. The weight-average molecular weights (Mw) ranged from52.3-40.2kg/mol and number-average molecular weights (Mn) ranged from34.8to12.3kg/mol, respectively. All the polymers were amorphous which were confirmed by XRD and soluble in in solvents such as DMSO, DMF and THF at room temperature. These poly(arylene ether)s exhibited high glass transition temperatures which all above217℃in DSC. TG studies showed that these polymers were stable to380℃as measured by5%weight loss temperatures in nitrogen. PAENs had tensile strength of55-90MPa, elongations at break of6.6-14.8%, and tensile moduli of1.28-1.69GPa, indicating their excellent mechanical properties.(2) After the conversion of carboxylic functions to carboxylate form, the new ion exchanger was prepared and used it as adsorbent to study the sorption behavior of heavy metal ions from aqueous solutions, copper and lead particularly. Various experimental conditions had been investigated including solution pH, contact time, initial metal ion concentrations and temperature. The maximum capacity was recorded as61.35mg/g for Cu(II) and175.4mg/g for Pb(II). The solution pH had a strong effect on equilibrium capacity with suitable values range from4to7. The process followed pseudo second-order kinetics and experimental data of the equilibrium obeyed linear, Langmuir, Freundlich, and Dubinin-Radushkevich equations. Thermodynamic studies showed that sorption of heavy metals were spontaneous and endothermic in nature. The uptake of heavy metals by the ion exchange resin was reversible and thus has good potential for practical application.(3) Using PAENs as macromolecular ligand,1,10-phenanthroline(Phen) as synergistic ligand, Eu3+and Tb3+as central ions, a series of novel rare earth functional polymeric materials with excellent fluorescent properties were prepared. Through solid UV-vis absorption and fourier transform infrared spectral analysis, we proved the rare earth had coordinated to backbones of polymer chains. Results from XRD confirmed a homogeneous distribution of rare earth ions within the polymer hostess, keep fluorescence quenching from happening. With appropriate amount of samples dissolved in DMF, we obtained the excitation and emission fluorescent spectra, with characteristic peak of Eu and Tb. With contents adjustment of Eu and Tb, color-tunable rare earth co-coordinated polymeric materials were prepared.