Self-oscillating polymeric refrigerator with high energy efficiency.

Electrocaloric and electrostrictive effects concurrently exist in dielectric materials. Combining these two effects could achieve the lightweight, compact localized thermal management that is promised by electrocaloric refrigeration. Despite a handful of numerical models and schematic presentations, current electrocaloric refrigerators still rely on external accessories to drive the working bodies and hence result in a low device-level cooling power density and coefficient of performance (COP).

Low-k nano-dielectrics facilitate electric-field induced phase transition in high-k ferroelectric polymers for sustainable electrocaloric refrigeration.

Ferroelectric polymer-based electrocaloric effect may lead to sustainable heat pumps and refrigeration owing to the large electrocaloric-induced entropy changes, flexible, lightweight and zero-global warming potential. Herein, low-k nanodiamonds are served as extrinsic dielectric fillers to fabricate polymeric nanocomposites for electrocaloric refrigeration. As low-k nanofillers are naturally polar-inactive, hence they have been widely applied for consolidate electrical stability in dielectrics.

Colossal electrocaloric effect in an interface-augmented ferroelectric polymer.

The electrocaloric effect demands the maximized degree of freedom (DOF) of polar domains and the lowest energy barrier to facilitate the transition of polarization. However, optimization of the DOF and energy barrier-including domain size, crystallinity, multiconformation coexistence, polar correlation, and other factors in bulk ferroelectrics-has reached a limit. We used organic crystal dimethylhexynediol (DMHD) as a three-dimensional sacrificial master to assemble polar conformations at the heterogeneous interface in poly(vinylidene fluoride)-based terpolymer.

Self-regulated underwater phototaxis of a photoresponsive hydrogel-based phototactic vehicle.

Incorporating a negative feedback loop in a synthetic material to enable complex self-regulative behaviours akin to living organisms remains a design challenge. Here we show that a hydrogel-based vehicle can follow the directions of photonic illumination with directional regulation inside a constraint-free, fluidic space. By manipulating the customized photothermal nanoparticles and the microscale pores in the polymeric matrix, we achieved strong chemomechanical deformation of the soft material.

High-entropy polymer produces a giant electrocaloric effect at low fields.

More than a decade of research on the electrocaloric (EC) effect has resulted in EC materials and EC multilayer chips that satisfy a minimum EC temperature change of 5 K required for caloric heat pumps. However, these EC temperature changes are generated through the application of high electric fields (close to their dielectric breakdown strengths), which result in rapid degradation and fatigue of EC performance. Here we report a class of EC polymer that exhibits an EC entropy change of 37.