New Polyurethane/Docosane Microcapsules as Phase‐Change Materials for Thermal Energy Storage

Abstract

Polyurethane microcapsules were prepared by mini-emulsion interfacial polymerization for encapsulation of phase-change material (n-docosane) for energy storage. Three steps were followed with the aim to optimize synthesis conditions of the microcapsules. First, polyurethane microcapsules based on silicone oil core as an inert template with different silicone oil/poly(ethylene glycol)/4,4'-diphenylmethane diisocyanate wt % ratio were synthesized. The surface morphology of the capsules was analyzed by scanning electronic microscopy (SEM) and the chemical nature of the shell was monitored by Fourier transform infrared spectroscopy (FT-IR). Capsules with the silicone oil/poly(ethylene glycol)/4,4'-diphenylmethane diisocyanate 10/20/20 wt % ratio showed the best morphological features and shell stability with average particle size about 4 μm, and were selected for the microencapsulation of the n-docosane. In the second stage, half of the composition of silicone oil was replaced with n-docosane and, finally, the whole silicone oil content was replaced with docosane following the same synthetic procedure used for silicone oil containing capsules. Thermal and cycling stability of the capsules were investigated by thermal gravimetric analysis (TGA) and the phase-change behavior was evaluated by differential scanning calorimetry (DSC).

Confined‐Volume Effect on the Thermal Properties of Encapsulated Phase Change Materials for Thermal Energy Storage

“…Face‐centered orthorhombic phase appears as a sharp peak at 21.42° and the hexagonal packed phase appears at 21.80° as a small peak. It has been found that those rotators coexist with the triclinic phase during the cooling process when n ‐docosane is microencapsulated . Microcapsules of 2 μm size (Figure e) present the peaks already mentioned for the other sizes of microcapsules, but it is noticeable that for this size of capsule they appear as more defined peaks.…”

“…FTIR spectra of the microencapsulated n ‐docosane (see Supporting Information, Figure S4) show the characteristic absorption bands for the polyurethane and for n ‐docosane, implying that the n ‐docosane has been successfully encapsulated into the PU shell.…”

“…Scheme shows the procedure followed to synthesize the microcapsules by mini‐emulsion interfacial polymerization . First, an aqueous solution containing poly(vinyl alcohol) (PVA, 1.6 g) in distilled water (80 mL) was prepared.…”

Study on the preparation, characterization, and release behavior of carbosulfan/polyurethane microcapsules

“…Polyurethane microcapsules, a polyurethane product, are receiving increasing attention for their high thermal and mechanical stabilities, corrosion resistance, biocompatibility, and low cost. Due to these properties, polyurethane microcapsules have been widely applied in medicine, cosmetics, materials, and pesticides . Isocyanates, including toluene diisocyanate (TDI), methylene diphenyl isocyanate (MDI), and their modified derivatives, are common precursors for preparing polyurethane microcapsules.…”

Review and in silico analysis of fermentation, bioenergy, fiber, and biopolymer genes of biotechnological interest inAgaveL. for genetic improvement and biocatalysis

“…Sixteen different fatty acids have been identified in mature stems of Agave plants, demonstrating the high potential of the genus as a candidate for fatty acid production in cell suspensions cultured in vitro. Among the n‐alkanes detected in the genus Agave is n‐docosane, a compound with many domestic and industrial applications in construction and in laboratories, and of high potential due to its energy storage capacity, lack of toxicity, non‐corrosive nature, low cost, and stability . Finally, the industrial wastes of Agave have been of interest for obtaining molecular hydrogen …”