Microencapsulation of stearic acid with SiO2 shell as phase change material for potential energy storage

Abstract

Stearic acid (SA) is being used as phase change material (PCM) in energy storage applications. In the present study, the microencapsulation of SA with SiO2 shell was carried out by sol–gel method. Different amounts of SA (5, 10, 15, 20, 30 and 50 g) were taken against 10 ml of tetraethyl orthosilicate (TEOS) for encapsulation. The synthesized microencapsulated PCM (MEPCM) were characterized by Fourier transform infrared spectroscope (FT-IR), X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The characterization results showed that SA was successfully encapsulated by SiO2. Thermogravimetric analysis (TGA) exhibited better thermal stability of the MEPCM than SA. The enthalpy values of MEPCM were found to be unchanged even after 30 heating–cooling cycles by differential scanning calorimetry (DSC). The latent heats of melting and solidification of 50 g SA containing MEPCM were found to be highest i.e. 182.53 J/g and 160.12 J/g, respectively among all microencapsulated samples. The encapsulation efficiency values were calculated using thermal data and the efficiency was found to be highest i.e. 86.68% in the same sample.

Photo/Thermo Dual Stimulus-Responsive Liquid Marbles Stabilized with Polypyrrole-Coated Stearic Acid Particles

“…In the spectrum of SA particles, the absorptions due to symmetric C−H stretching of −CH 2 groups at 2926 cm −1 , antisymmetric C−H stretching of −CH 2 groups at 2853 cm −1 , stretching vibration of C�O at 1703 cm −1 , and C−O−H in-plane angular vibration at 1467 cm −1 were observed. 48 In the spectrum of the PPy-Cl homopolymer, the C−C stretching vibrations in the pyrrole ring at 1550 cm −1 and the C−H and N−H in-plane deformation vibrations at 1028 and 1159 cm −1 , respectively, were observed. 62 In the spectra of SA/PPy particles (5 and 10 wt % Py), the absorptions originating from both SA and PPy were observed, indicating the introduction of PPy to SA particles.…”

“…The FT-IR spectra of SA particles and SA/PPy particles are depicted in Figure S4. In the spectrum of SA particles, the absorptions due to symmetric C–H stretching of −CH 2 groups at 2926 cm –1 , antisymmetric C–H stretching of −CH 2 groups at 2853 cm –1 , stretching vibration of CO at 1703 cm –1 , and C–O–H in-plane angular vibration at 1467 cm –1 were observed . In the spectrum of the PPy-Cl homopolymer, the C–C stretching vibrations in the pyrrole ring at 1550 cm –1 and the C–H and N–H in-plane deformation vibrations at 1028 and 1159 cm –1 , respectively, were observed .…”

“…To produce the light-induced disruption system, we first synthesized core–shell particles based on stearic acid (SA) particles covered with a polypyrrole (PPy) overlayer (SA/PPy particles) by aqueous chemical oxidative seeded dispersion polymerization as an LM stabilizer. SA is a natural molecule exhibiting a solid-to-liquid transition linked to the melting point, and it is described as phase-change material and responsive molecule. − The PPy is well known to work as a light-to-heat photothermal transducer, , allowing melting of the SA core component via near-infrared (NIR) laser light irradiation. We then studied the structure and stability of the LMs stabilized using the SA/PPy particles against heating.…”

Photo- and Thermoresponsive Liquid Marbles Based on Fatty Acid as Phase Change Material Coated by Polypyrrole: From Design to Applications

“…FT-IR studies were conducted to characterize chemical composition of the composite particles (Figure S5). The FA particles showed absorptions at around 2916 cm −1 , 2845 cm −1 , 1698 cm −1 , and 1463 cm −1 , which can be assigned to symmetric C−H stretching of −CH 2 groups, antisymmetric C−H stretching of −CH 2 groups, stretching vibration of C=O, and C−O−H in-plane angular vibration, 47 respectively. The PPy-Cl homopolymer showed absorptions at 1550 cm −1 , 1028 cm −1 , and 1159 cm −1 , which can be attributed to the C−C stretching vibrations in the Py ring and the C−H, N−H in plane deformation vibrations, 67 respectively.…”

“…Recently, we succeeded in realization of LMs, which can disrupt by application of light and temperature dual stimuli, using the core–shell particles based on stearic acid (SA) core covered with a polypyrrole (PPy) overlayer (SA/PPy particles) as an LM stabilizer . SA has an alkyl chain with 18 carbons and a corresponding melting point at 69 °C and has been used widely as a PCM. ,− PPy is one of the conjugated polymers, which can efficiently transduce near-infrared (NIR) light into heat, , enabling melting of SA core by NIR light irradiation. The presence of SA, as a PCM, and PPy, as photothermal converter, gave rise to the photo and thermo dual stimulus-responsive characters of the LMs.…”