Catalyst‐free ammonolysis of PTT polyester: Thermodynamics, kinetics, and selective recovery of 1,3‐propanediol

Chemical upcycling of polyesters presents a sustainable pathway to mitigate plastic waste accumulation while enabling monomer valorization and recovery. Here, we demonstrate a catalyst‐free ammonolysis of poly(trimethylene terephthalate) and selective recovery of 1,3‐propanediol. Non‐dissociated aqueous ammonia () was identified as the actual reactive species for ester bond cleavage. Essential physical and thermodynamic properties were determined through combined experimental and group‐contribution methods, while phase equilibria were quantified using an integrated electrolyte NRTL and Redlich‐Kwong model. Based on the activity of and kinetic data, a phenomenological semi‐empirical kinetic model was developed and validated. This model captures both induction period and main reaction stage through a power‐law expression coupled with a time‐dependent logistic function, supporting a depolymerization mechanism that proceeds through concurrent heterogeneous shrinking‐core and homogeneous reaction. Furthermore, an integrated extraction‐distillation process was developed to achieve controlled purity and high recovery of 1,3‐propanediol.