Vitrimer Transition Temperature Identification: Coupling Various Thermomechanical Methodologies

Vitrimers hold great promise as adaptive materials capable of shape reconfigurability, welding, and self-healing due to dynamic covalent reactions occurring above the vitrimer transition temperature (T-v). Previous literature reports the T-v as one value influenced mainly by chemistry; however, literature also reports significant inconsistencies when measuring or identifying T-v trends. Herein, we present unique data interpretation methods to analyze stress-relaxation and elongational creep results allowing for excellent agreement between multiple T-v measurement methodologies. We also demonstrate that experimental parameters (e.g., heating rate and applied axial force) and catalyst concentration are crucial in dictating the T-v range. Varying the catalyst concentration or sample heating rate shifts the T-v up to 115 and 43 degrees C, respectively. Additionally, we present a kinetic model confirming the temperature dependence of the transesterification rate-limiting step, exhibiting excellent agreement with experimental data. Fundamentally understanding the T-v will inform future design of vitrimers toward applications ranging from recyclable actuators to structural adhesives.