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Adsorption of organic phase-change materials (PCMs) by the porous matrix of microfibrillar cellulose (MFC) is a simple and versatile way to prepare shape-stable phase-change composites, which are promising as sustainable thermoregulating additives to construction materials. However, due to MFC inherent morphology, the resulting composites have relatively low poured density that complicates their introduction in sufficient amounts, for instance, into mortar mixes. Unlike MFC, fungal mycelium has, by an order, less fibrils thickness and, thus, possesses significantly higher poured density. Herein, we studied the feasibility of fungal mycelium-based matrices as alternative biopolymeric porous supports for preparation of sustainable and shape-stable phase-change composites. Two methods were employed to prepare the porous mycelium-based supports. The first one was the solid-state fermentation, which resulted in partial biotransformation of MFCs to mycelium hyphae, while the second one was the liquid-state surface fermentation, used to cultivate the reference matrix of Trametes hirsuta hyphae. The phase-change composites were prepared by adsorption of model organic PCMs on porous biopolymer matrices. The mass ratio of support/PCM was 40/60 wt%. The composites were studied with respect to their structure, composition, poured density, latent heat storage properties, and thermal and shape stability. The employment of the partially transformed to mycelium-hyphae MFC fibers was found to be a suitable way to prepare phase-change composites with improved poured density while preserving a reasonable latent heat capacity and shape stability as compared to the MFC/PCM composites. [ABSTRACT FROM AUTHOR]

Hybrid materials composed of porous vaterite CaCO 3 microcrystals loaded with functional inorganic nanoparticles are actively studied with respect to various practical applications. Recently, freezing-induced loading method was demonstrated as a versatile and effective approach for preparation of vaterite-based functional hybrid microparticles. However, despite of its high efficiency, the effect of nanoparticle concentration on the freezing-induced loading process and the structural properties of the resulted hybrids were not studied previously. Herein, for the first time, we have evaluated the feasibility of the conventional adsorption models to describe the freezing-induced loading of citrate-capped silver nanoparticles (AgNPs). The fitting of the dependence of the loading capacity of vaterite crystals on the residual concentration of AgNPs to two- or three-parameter models revealed that the best fit was obtained with the Freundlich model (R2 = 0.969), suggesting non-uniform deposition of AgNPs and interparticle agglomeration (Freundlich n > 1). This was confirmed with electron microscopy and elemental analysis demonstrating the formation and growth of AgNP aggregates on the CaCO 3 surface with increasing initial nanoparticle concentration. Overall, the reported findings are valuable for a better understanding of the freezing-induced loading process and for further optimization of the preparation of vaterite-based functional hybrid microparticles. [Display omitted] • Ag/CaCO 3 composites were prepared by freezing-induced loading of citrate-capped AgNPs. • Conventional adsorption models can be used to describe the deposition of AgNPs. • The increase in AgNPs concentration led to deviation from Langmuir-type deposition. • The freezing-induced loading of AgNPs can be well described with the Freundlich model. • The change in AgNPs concentration allows to control Ag/CaCO 3 surface morphology. [ABSTRACT FROM AUTHOR]

• Halloysites (HNTs) are suitable containers for freezing-induced loading (FIL). • FIL of AuNPs into HNTs has an efficiency of 85% after 5 loading cycles. • FIL is twice efficient than vacuum impregnation and adsorption from solution. • FIL efficiency may be improved by adjusting the size and concentration of NPs. Au nanoparticles were loaded into halloysite nanotubes by freezing-induced loading method. The loading efficiency and Au nanoparticle distribution were studied by UV–Vis absorption spectroscopy and transmission electron microscopy and compared to those of vacuum impregnation and adsorption from solution loading methods. The freezing-induced loading was found to be the most effective with the loading efficiency up to 85% after 5 loading cycles and the best Au nanoparticle distribution into halloysite nanotubes. [ABSTRACT FROM AUTHOR]