Electrospun Shape-Stabilized Phase Change Materials Based on Photo-Crosslinked Polyethylene Oxide

Abstract

Phase change materials (PCMs) in the form of fibers or fibrous mats with exceptional thermal energy storage ability and tunable working temperature are of high interest to produce smart thermoregulating textiles, useful for increasing human thermal comfort while avoiding energy waste. Common organic PCMs suffer from instability in their molten state, which limits their applicability as highly performing fibrous systems. In this work, electrospun fibrous mats made of polyethylene oxide (PEO), a PCM with excellent thermal properties and biocompatibility, were fabricated and their shape instability in the molten state was improved through UV photo-crosslinking. The characterization aimed to assess the performance of these shape-stable electrospun mats as nanofibrous PCMs for thermal management applications. In addition to an enhanced resistance to water-based solvents, UV-cured electrospun PEO mats demonstrated a remarkable latent heat (≈112 J/g), maintained over 80 heating/cooling cycles across the phase change temperature. Moreover, their morphological stability above their melting point was demonstrated both macroscopically and microscopically, with the retention of the initial nanofibrous morphology. Tensile mechanical tests demonstrated that the UV crosslinking considerably enhanced the ultimate properties of the fibrous mat, with a five-fold increase in both the tensile strength (from 0.15 MPa to 0.74 MPa) and the strain at break (from 2.5% to 12.2%) compared to the uncrosslinked mat. In conclusion, the photo-crosslinked electrospun PEO material exhibited high thermal properties and good shape stability without displaying leakage; accordingly, in the proposed PCM system, the necessity for encapsulation or use of a supporting layer has been eliminated. Photo-crosslinking thus proved itself as an effective, fast, and environmentally friendly method to dramatically improve the shape-stability of nanofibrous PEO electrospun mats for smart thermoregulating textiles.

Waste plastic to energy storage materials: a state-of-the-art review

“…The instability of common organic PCMs in the molten state limits their future applications. Fredi et al 214 developed electrospun fiber felt made of polyethylene oxide (PEO), a PCM with outstanding thermal property and biocompatibility, and increased its shape instability in the molten state via ultraviolet (UV) light cross-linking. In addition to enhanced resistance to water-based solvents, UV-cured electrospun PEO pads displayed considerable latent heat (112 J g −1 ) that was maintained for more than 80 heating and cooling cycles at the whole phase change temperature.…”

Water-Resistant Photo-Crosslinked PEO/PEGDA Electrospun Nanofibers for Application in Catalysis

“…While PEO use is almost relegated to biomedical and healthcare applications [ 43 , 44 , 45 , 46 , 47 , 48 , 49 ], its usage in other fields is uncommon, such as in composite laminates for hindering delamination [ 36 ] and as phase change materials (PCMs) [ 50 ]. Even PEO application in catalysis is limited to a few reported cases [ 51 , 52 , 53 ]; however, it has never been shaped into nanofibers for catalytic purposes.…”

Electrospun PEO/PEG fibers as potential flexible phase change materials for thermal energy regulation

“…[21][22][23][24] In search of a flexible material for textiles, wearable devices, and thermal bandages, different types of flexible FSPCMs have been developed in the form of membranes/films/sheets, shape memory polymers, or fibers. They can be fabricated via different methods such as melt blending of PCM-polymer mixture, [25,26] PCM diffused or impregnated within a 3D flexible polymer matrix, [13,27] melt-spun [28] or electrospun [29,30] into micro or nano PCM fibers etc. Of these materials, fibers are in particularly interesting in cooling applications given the porosity and large surface area of the material which allow for efficient heat exchange.…”

“…[37] They are usually low molecular weight, non-volatile compounds, and a compatible plasticizer should be able to tune the fiber's physical properties without affecting the fiber's chemical nature. [38] PCMs are also often incorporated into the fibers in the form of microcapsules, [39] direct mixing [36] with the polymer solution and electrospun as fibers, or via a post fabrication step of crosslinking [29,40] with the components to generate a thermo-regulating fabric.…”

“…Unfortunately, form-stability was not reported and we are unable to evaluate the effectiveness of PEO as a fibrous matrix. Fredi et al [29] on the hand fabricated a form-stable PEO fibrous mat by crosslinking the PEO chains with trimethylolpropane triacrylate crosslinker. With PEO as the PCM and matrix, its tensile strength and strain at break improved by 5 times after crosslinking, and was form-stable with no weight loss when heated to 100 • C for 2 min.…”