Magnetic Polyurethane Microcarriers from Nanoparticle-Stabilized Emulsions for Thermal Energy Storage

Abstract

Hydrated inorganic salts are phase change materials (PCMs) with promising thermal energy storage capacity. However, their application is commonly restricted because of problems of phase segregation, incongruent melting, cycling instability, or supercooling. This work presents an encapsulation method of hydrophilic PCMs that allows for the incorporation of additional functionalities within a protective shell occluding a storage core. Interfacial polymerization in nanoparticle-stabilized inverse emulsions (also called "Pickering emulsions") is used as a synthetic platform to guarantee the stability and latent heat storage efficiency of sodium sulfate decahydrate, taken as a model case of a hydrated salt. Thus, functional polyurethane hybrid microcapsules with magnetic and/or catalytic species (e.g., CeO 2 , TiO 2 , Fe 3 O 4 ) accessible on the surface were used for the encapsulation of an aqueous solution of sodium sulfate decahydrate salt. The hermeticity of the polyurethane shell combined with the thermal conductivity of magnetite nanoparticles and the nucleating ability of a second salt with a similar structure (e.g., sodium dihydrogen phosphate dihydrate) guaranteed the chemical stability, recyclability, and a minimization of the supercooling of the phase change material. Magnetically recoverable microcarriers, with high storage capacity and stability, are proposed for the controlled storage and release of thermal energy at living temperatures.

Static and dynamic magnetization models of magnetic nanoparticles: an appraisal

“…Reprinted with permission from [40], copyright 2022 American Chemical Society. Reprinted with permission from [41], copyright 2020 American Chemical Society. Reprinted with permission from [42], copyright 2014 De Gruyter.…”

Shape-Stable Hybrid Emulsion Gel with Sodium Acetate Trihydrate and Paraffin Wax for Efficient Solar Energy Storage and Building Thermal Management

“…The microencapsulation technique involves enveloping hydrated salts in wax to prevent moisture loss and enhance stability and cycling performance. − Pickering emulsion is a method of preparing microcapsules that employs solid nanoparticles as surface-active agents to stabilize two immiscible phases, resulting in a dispersed system with good stability and controllability. − It can effectively combine the properties of organic and inorganic components, making it crucial for the thermal performance of composite PCMs. Wang et al achieved a shape-stable composite material (HPC@EG) by emulsifying hydrated salts and PW to form an oil-in-water Pickering emulsion, mixing it with expanded graphite, and then mechanically compressing it.…”

Nanoencapsulation of Organic Phase Change Materials in Poly(3,4-Ethylenedioxythiophene) for Energy Storage and Conversion

“…An efficient and versatile technique for the nanoencapsulation of PCMs has been miniemulsion polymerization [ 29 , 33 , 34 ]. Polymeric shells are stable in a reasonable temperature range, hermetic, and flexible, which allows them to adapt perfectly to changes in the volume of the PCM.…”