Synthesis and Nanoencapsulation of Poly(ethylene glycol)-Distearates Phase Change Materials for Latent Heat Storage and Release

Abstract

Phase change materials (PCMs) are essential candidates for thermal energy storage and management. In this work, a library of PCMs with a wide range of phase transition temperatures and latent heat storage capacities was synthesized using green and catalyst-free esterification reactions of stearic acid with different molecular weight of poly(ethylene glycol) (PEG). In this process, the phase transition temperature and phase change enthalpies of synthesized PCMs were easily tuned by changing the molecular weight of PEG. The resultant PEG-distearates showed melting temperature in the range of 34.8−52.9 °C, with the latent heat storage capacities ranging from 121.5 to 145.1 J/g, depending on the molecular weight of PEG. These PCMs have a pleasant odor, do not undergo sublimation during their heating process, and are noncorrosive. Furthermore, to enhance its practical applicability, the PEG-distearate synthesized with PEG having 6000 MW (E6000) was nanoencapsulated into a thin silica shell using a miniemulsion-assisted sol−gel method. The nanoencapsulated E6000@SiO 2 showed excellent phase change performance with more than 48% encapsulation efficiency, 100% of heat storage capacity, and more than 98% retention of heat storage capacity after continuous 50 cycles of heating and cooling.

Solvent-Assisted Nanochannel Encapsulation of a Natural Phase Change Material in Polystyrene Hollow Fibers for High-Performance Thermal Energy Storage

“…To date, many organic and inorganic materials have been employed as PCMs in solar energy storage, building and construction, packaging, textiles, electronics, medicines, among others . Common PCMs include fatty acids, fatty alcohols, paraffins, esters, polymers, oils, salt hydrates, oxides, and metals. − For example, paraffin waxes, a type of organic PCMs, were incorporated in building frames, like walls, floors, and roofs to improve energy efficiency in buildings as well as to achieve a comfortable living . Coupled with inorganic PCMs (e.g., oxides), paraffin waxes were embedded into fibrous materials of smart textiles such as sleeping bags, coats, gloves, and shoes to achieve enhanced thermoregulating performance for outdoor activity. − As a class of biodegradable and biocompatible PCMs, natural fatty acids were applied as a switch for temperature-controlled release of therapeutics. , Since PCMs lose their mechanical strength or shape stability during the melting process, they must be encapsulated in physically strong and chemically stable shells to form form-stabilized structures for thermal energy charging and discharging .…”

A Review of Composite Phase Change Materials Based on Porous Silica Nanomaterials for Latent Heat Storage Applications

“…Fatty acid esters of PEG can be used as phase change materials with higher melting points than pure PEG [ 170 ]. 61.6% wt.…”

“…PCMs were also used as additives in cement mortar for buildings external walls in order to reduce the indoor temperature fluctuations [ 170 , 171 ]. PEG 600 was impregnated into fumed silica under vacuum.…”

Tuning Mg(OH)2 Structural, Physical, and Morphological Characteristics for Its Optimal Behavior in a Thermochemical Heat-Storage Application

“…Indeed, TES systems integrated into industrial processes and domestic users can face energy efficiency issues, improve the use of renewable resources, and reduce greenhouse gas emissions [ 6 ]. As one promising alternative to the storage of sensible [ 7 , 8 ] or latent heat [ 9 , 10 , 11 ], heat storage through reversible chemical reactions is under investigation [ 12 , 13 ]. By this method, the separated components of the thermochemical material (TCM) during the heating are stored in separate vessels to be recombined to generate heat when needed [ 14 , 15 ].…”