Modeling Impact of Regiodefects on the Electrocaloric Effect in Poly(VDF-co-TrFE) Copolymers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Polymer Science

Background:

• The electrocaloric effect in poly(VDF-co-TrFE) is linked to a first-order phase transition between ferroelectric and paraelectric phases.
• Understanding factors influencing this transition is crucial for optimizing electrocaloric materials.

Purpose of the Study:

• To investigate the impact of regiodefects on the electrocaloric effect in poly(VDF-co-TrFE).
• To develop and validate an analytical model incorporating regiodefects for predicting material behavior.

Main Methods:

• Molecular dynamics (MD) simulations to observe phase transition behavior with regiodefects.
• Development of a modified Landau phenomenological theory for the analytical model.
• Calibration of model parameters using MD simulations of poly(VDF-co-TrFE) crystals.

Main Results:

• Regiodefects transform the first-order phase transition into a more gradual, second-order transition.
• The analytical model accurately predicts polymer polarization (P) and adiabatic temperature change (ΔT) as functions of temperature, electric field, and defect concentration.
• Model predictions with regiodefects show significantly better agreement with experimental data.

Conclusions:

• Regiodefects play a critical role in modifying the electrocaloric properties of poly(VDF-co-TrFE).
• The developed analytical model provides a valuable tool for understanding and designing ferroelectric polymers for electrocaloric applications.