Document Type: Research Paper
The main objective of this search was to prepare novel soluble polyureas with improved thermal
stability. Accordingly, a new types of polyureas was prepared through the polycondensation
reaction of a prepared diamine containing ether, keto, and naphthyl groups with
4,4’-diphenylmethan diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), and isophorone
diisocyanate (IPDI) in N-methyl-2-pyrrolidone (NMP). Conventional spectroscopic methods
and elemental analysis were used to characterize the structure of the monomer and polymers.
The results showed that polyurea samples with the expected structure were synthesized. The
inherent viscosity of polymers at a concentration of 0.5 g/dL in NMP at 30 °C was in the range
of 0.55-0.60 dL/g. Thermal properties of resultant polyureas were investigated by differential
scanning calorimetry and thermogravimetric analysis, and they indicated improved thermal
stabilities in comparison with common polyureas. Physical properties of the polymers were
also studied; they were soluble in common dipolar aprotic solvents. MDI-based polyurea
showed highest thermal stability and lowest solubility among the prepared polymers.