Thermodynamics of dimethylene urethane,of its ring‐opening polymerization,and of poly(dimethylene urethane) between 0 and 335 K

In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C ⁰_p of dimethylene urethane (DMU) and poly(dimethylene urethane) (PDMU) was studied between 6 and 335 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield, the energies of combustion ΔU_comb of the monomer and of the polymer were measured. From the experimental data, the thermodynamic functions C ⁰_p (T), H ⁰ (T)–H ⁰ (0), S ⁰ (T), G ⁰ (T)–H ⁰ (0) were calculated in the range from 0 to 335 K, and enthalpies of combustion ΔH ⁰_comb and thermochemical parameters of formation ΔH ⁰_f, ΔS ⁰_f, ΔG ⁰_f of the substances studied were estimated at T = 298.15 K and standard pressure. The results were used to calculate the thermodynamic characteristics of the ring‐opening polymerization of DMU in bulk (ΔH ⁰_pol, ΔS ⁰_pol, ΔG ⁰_pol) with formation of linear poly(dimethylene urethane) in the range from 0 to 330 K. In addition, the ceiling temperature T ⁰_ceil was determined.