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Latent heat storing calcium alginate microcapsules were manufactured by a repeated interfacial coacervation/crosslinking method. By using a high-viscosity sodium alginate for the capsule formation, the paraffin phase change material (PCM) content was substantially enhanced related to the recently developed procedure. The maximization of PCM loading was achieved using experimental design for paraffin containing microcapsules. The microcomposites were optimized for 81.5 % PCM content with uniform size of 2.20 ± 0.14 mm. In some applications e.g. packaging, the biodegradable character of the materials is especially beneficial, hence for the manufacture of entirely eco-friendly heat storing microcomposites coconut oil PCM was microencapsulated by the same procedure. The process originally developed and optimized for paraffin was scaled-up by two orders of magnitude, accordingly, the outstanding PCM content was reproduced also with coconut oil (average value 81.1 %). The high PCM content was reflected also in the heat storing capacity measured by differential scanning calorimetry. The easily upscalable, spherical and core/shell structured, entirely biocompatible microcapsules with thermally stable calcium alginate coating could be developed for industrial application.

Microencapsulation of phase change materials (PCMs) is an attractive opportunity for broadening their applications. In this respect, a novel encapsulating polymer, ethyl cellulose (EC) was used to entrap n-hexadecane (HD) PCM by an emulsion-solvent evaporation method. Emulsifiers strongly influenced the size and morphology of the forming EC-HD composite microcapsules, and they also had a great impact on their thermal properties. All of the three emulsifiers were suitable to prepare quasi core-shell microparticles, though the high porosity of shells resulted in serious leakage in composites prepared by Tween 80, and permeability of particles manufactured by poly(vinyl alcohol) (PVA), as can be stated from scanning electron microscopy and differential scanning calorimetry analysis. Interfacial tension measurements and spreading coefficient analysis enabled the prediction of preparation conditions for usable core-shell microcapsules. Volume weighted mean diameters of the microparticles were 319 m, 92 m and 85 m formed by Tween 80, PVA and poly(methacrylic acid sodium salt) (PMAA), repectively. A significantly higher HD content and latent heat storage capacity could be achieved using PVA and PMAA than with Tween 80. The thermal cycling test indicated good thermal reliability of microcapsules prepared by PMAA, while the energy-storing capacity of composites prepared by PVA decreased substantially, and a dramatic reduction was found in microparticles using Tween 80.

Double-shell alginate microcapsules containing paraffin phase change material (PCM) were prepared for latent heat storage by a method of repeated interfacial coacervation/crosslinking.The proposed process consisted of three main steps: (1) preparation of paraffin containing core particles by dripping an O/W emulsion of melted paraffin and aqueous sodium alginate into a calcium chloride ionic cross-linking solution, (2) encapsulation of the core particles into double alginate shell by ionic gelation/crosslinking by repeated interactions between the sodium alginate and calcium chloride solutions, and (3) consolidation of the capsule shells by contact heat treatment. The effects of process parameters such as the sodium alginate concentration, the calcium chloride concentration in certain stages of the process, and the contact time between the formed core particles and the surrounding alginate solution on the paraffin content and the mean diameter of capsules were studied by experimental design and statistical evaluations. The prepared PCM capsules had uniform sizes, core/shell structure, double-walled non-porous alginate coating, tunable void space inside the core, and suitably high paraffin content at properly selected process conditions, corresponding to 95.0 J/g melting and 91.7 J/g freezing latent heat capacity. Thermogravimetric analysis and repeated thermal cycling evidenced good thermal stability, and proper mechanical strength for leakage free microcapsules.

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Plant UCPs are proved to take part in the fine-tuning of mitochondrial ROS generation. It has emerged that mitochondrion can be an important early source of intracellular ROS during plant-pathogen interaction thus plant UCPs must also play key role in this redox fine-tuning during the early phase of plant–pathogen interaction. On the contrary of this well-established assumption, the expression of plant UCPs and their activity has not been investigated in elicitor induced oxidative burst. Thus, the level of plant UCPs both at RNA and protein level and their activity was investigated and compared to AOX as a reference in Arabidopsis thaliana cells due to bacterial harpin treatments. Similar to the expression and activity of AOX, the transcript level of UCP4, UCP5 and the UCP activity increased due to harpin treatment and the consequential oxidative burst. The expression of UCP4 and UCP5 elevated 15-18-fold after 1 h of treatment, then the activity of UCP reached its maximal value at 4h of treatment. The quite rapid activation of UCP due to harpin treatment gives another possibility to fine tune the redox balance of plant cell, furthermore explains the earlier observed rapid decrease of mitochondrial membrane potential and consequent decrease of ATP synthesis after harpin treatment.

Macroporous sorbents differing in size were prepared by the 2,2ʹ-azobis(isobutyronitrile) (AIBN)-initiated suspension radical polymerization of glycidyl methacrylate and ethylene dimethacrylate in the presence of an inert porogen. The microspheres were loaded with paraffin and cetyl alcohol phase change materials (PCMs) and coated with silica by sol-gel method using trimethoxy(methyl)silane hydrolysate. The energy storing capacity of the PCM-containing composite particles was monitored by differential scanning calorimetry. Accelerated thermal cycling tests were carried out to determine the thermal reliability of the microencapsulated PCMs. Paraffin and cetyl alcohol content in the microcapsules was 42.9 wt.% and 48.9 wt.%, respectively. The microcomposites with higher PCM content showed correspondingly higher latent heat storage capacity (melting and solidification enthalpies were 96.1 J/g and 94.5 J/g, respectively). However, there was low enthalpy change observed after 1000 thermal cycles of cetyl alcohol-containing capsules, which indicated that PCM leakage from the microspheres was minimal.

Latent heat storage by phase change materials (PCM) is a promising way of thermal energy storage for equilibrating the daily fluctuation of temperature in office-and home buildings. Bio-originated compounds have got great importance to evade further plastic contamination all over the world. Durability of biodegradable natural materials by means of environmentally friendly agents is an exciting challenge. In this study Ca alginate-coconut oil eco-friendly coreshell PCM microcapsules were functionalized with Ag nanoparticles, following their synthesis using harmless reducing agents. Throughout the preparation of the PCM microcapsules by repeated interfacial coacervation/crosslinking procedure, the Ag nanoparticles were homogeneously dispersed in the Ca alginate shell. High coconut oil content was achieved in the Ag nanoparticle-loaded microcapsules, which was not influenced by the Ag nanoparticle content. The high PCM content resulted in correspondingly high latent heat storing capability. The freezing and melting heat storing capacities were in the range of 83.6 and 85.6 J/g, as well as 89.7 to 92.6 J/g, respectively, matching to the extremely high PCM content in the range of 82.7% to 84.8% (m/m). Leaking of the heat storing microcapsules was not observed after 200 heating-cooling cycles. The Ag nanoparticle content did not influence the PCM ratio of the microcapsules, although as expected their antimicrobial potential was significantly enhanced by it. The highest Ag nanoparticle loading, that was 1.3% (m/m) related to the total mass of microcapsules, exerted excellent antibacterial and antifungal impact.