Green and selective synthesis of sulfonated poly(pyrimidine-amides) in ionic liquid and their nanocomposites based on carboxylated MWCNTs: Investigation on photophysical, solubility, thermal, and removal of ions behaviors

Abstract

The present work reports that imidazolium based ionic liquids (ILs) can be considered as effective catalysts and media for the selective synthesis of novel high performance sulfonated poly(pyrimidine-amides) (SPPAs) from a new diamine. SPPAs were obtained in 2.5 h at 110 °C that this obtained time is considerably shorter than the conventional direct polycondensation. The nanocomposites of SPPAs with carboxylated multi-walled carbon nanotubes (CMWCNTs) showed that a strong chemical bonding between the inorganic particles and the polymer matrix contributed to enhance thermal properties. The aliphatic SPPA (SPPA3) exhibited blue emission (λem = 445 nm), while the aromatic SPPAs exhibited green emission (λem = 473–484 nm). The SEM and TEM images showed that CMWCNTs were homogeneously distributed in the matrix of polymer without any agglomeration. A superb solubility of all SPPAs was seen in DMF, DMSO, DMAc, and NMP as polar aprotic solvents and even in pyridine and THF. The T10% value of SPPA2/5 wt% CMWCNTs enhanced from 411 ºC to 442 ºC with the char yield from 52% to 68% in N2 compared with blank SPPA2. The adsorption of Hg2+, Cd2+, Ni2+, Co2+, Cu2+, Cr+3, and Fe+3 in a multicomponent system was studied, and the results showed that the nanocomposite was more effective than the blank polymer due to the network formation and increase in the surface area of the nanocomposite.