Thermodynamics of depolymerization of biotechnological poly[(R)-3-hydroxybutyrate] with formation of (R,R,R)-4,8,12-trimethyl-1,5,9-trioxadodeca-2,6,10-trione and of its polymerization with ring-opening to highly isotactic poly[(R)-3-hydroxybutyrate] from 0 to 500 K at standard pressure

In adiabatic vacuum and dynamic calorimeters the temperature dependence of the heat capacity C p 0 of (R,R,R-4,8,12-trimethyl-1,5,9-trioxadodeca-2,6,10-trione (a twelve-membered cyclic trilactone), biotechnological poly[(R)-3-hydroxybutyrate] and highly isotactic poly[(R)-3-hydroxybutyrate] was studied between 5 K and 500 K ; temperatures and enthalpies of melting of the above mentioned substances were measured. In a calorimeter with a static bomb and an isothermal shield the energy of combustion of the same substances was measured. From the results the thermodynamic functions C p 0 (T), H 0 (T) - H 0 (0), S 0 (T), G 0 (T) - H 0 (0) were calculated in the range of 0 K to 500 K and thermochemical parameters ΔH 0 comb , ΔH f 0 , ΔS f 0 , ΔG f 0 were estimated at T = 298,15 K and standard pressure. The thermodynamic parameters of depolymerization of the biotechnological polymer to the 12-membered trilactone ΔH 0 depol , ΔS 0 depol , ΔG 0 depol and of the polymerization of the monomer formed in the highly isotactic poly[(R)-3-hydroxybutyrate] ΔH 0 pol , ΔS 0 pol , ΔG 0 pol were calculated for 0 K to 500 K.