Tailoring Hierarchical Interfaces Enhances Dielectric and Electrocaloric Performance in Relaxor Ferroelectric Polymers

Electrocaloric (EC) polymers have garnered significant attention in recent years due to their zero direct greenhouse gas emissions during cooling processes. However, only a few polymers exhibit sufficient refrigeration capacity at low fields, which limits the application of the EC cooling technology. In this work, we show that electrospinning, a mature polymer processing technology, can introduce a complex fibrous matrix that leads to nano-, meso-, and micro-scale structures, and hence a series of hierarchical polar interfaces. The following thermal treatment was applied to enhance breakdown fields and reduce dielectric losses. A series of polyvinylidene fluoride (PVDF)-based fluoropolymers containing cellulose acetate (CA) were prepared. By introducing 10 wt% of CA, the electrospinning process significantly improves the polar entropy of the fluoropolymer system and significantly improves the polymer’s breakdown strength, polarization, and electrocaloric performances, compared to their solution cast counterparts. The polar entropy variations among various polymeric composites were elucidated using data acquired from multiple structural characterization tools. By linking the optimized hierarchical interface structures and the overall EC performances, this study provides new routes for designing high-performance EC nanocomposites that can be facilely tailored by the matured processes of fibrous, polymeric composites.

Graphical Abstract