Solvothermal Polymerization of Diaminomaleonitrile Reveals Optimal Green Solvents for the Production of C=N-Based Polymers.

Solvothermal polymerization (STP) of diaminomaleonitrile (DAMN) was evaluated using a wide variety of solvents and in the temperature range from 80 to 170 °C. The highest yields, almost quantitative, were achieved with protic -alcohols such as -pentanol or -hexanol at 130 and 150 °C, respectively. The kinetic behavior was studied by gravimetry and the DAMN consumption was monitored by UV-vis spectroscopy and HPLC. GC-MS identified byproducts of the DAMN hydrolysis and oxidation reactions, which were significantly reduced when -pentanol or -hexanol were used with respect to hydrothermal conditions. This led to an exploration of compositional changes and microstructural variations by FTIR and NMR spectroscopy and simultaneous thermal analysis. -Hexanol appears to be an ideal eco-friendly solvent for the DAMN self-STP. The results presented here are not only of interest for the design of polymeric materials based on C=N structures but also show remarkable implications for prebiotic chemistry.