In this research, novel, organic, solid-liquid phase-change materials (PCMs) derived from methoxy polyethylene glycol (MPEG) and aromatic acyl chlorides (ACs) were prepared through a condensation reaction. The MPEGs were used as phase-change functional chains with different molecular weights (350, 550, 750, 2000, and 5000 g/mol). The aromatic ACs, terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC), were employed as bulky linker cores. Solubility tests demonstrated that this family of PCMs is soluble in protic polar solvents such as H₂O and MeOH, and insoluble in nonpolar solvents such as n-hexane. Fourier-ransform infrared spectroscopy (FT-IR UATR) and nuclear magnetic resonance (¹H, ¹³C, DEPT 135°, COSY, HMQC, and HMBC NMR) were used to confirm the bonding of MPEG chains to ACs. The crystalline morphology of the synthesized materials was examined using polarized optical microscopy (POM), revealing the formation of spherulites with Maltese-cross-extinction patterns. Furthermore, it was confirmed that PCMs with higher molecular weights were crystalline at room temperature and exhibited an increased average spherulite size compared to their precursors. Thermal stability tests conducted through thermogravimetric analysis (TGA) indicated decomposition temperatures close to 400 °C for all PCMs. The phase-change properties were characterized by differential scanning calorimetry (DSC), revealing that the novel PCMs melted and crystallized between −23.7 and 60.2 °C and −39.9 and 45.9 °C, respectively. Moreover, the heat absorbed and released by the PCMs ranged from 57.9 to 198.8 J/g and 48.6 to 195.6 J/g, respectively. Additionally, the PCMs exhibited thermal stability after undergoing thermal cycles of melting-crystallization, indicating that energy absorption and release occurred at nearly constant temperatures. This study presents a new family of high-performance organic PCMs and demonstrates that the orientation of substituent groups in the phenylene ring influences supercooling, transition temperatures, and thermal energy storage capacity depending on the MPEG molecular weight.

Ionenes are poly(ionic liquids) (PILs) comprising a polymer backbone with ionic groups along the structure. Ionenes as solid–solid phase change materials are a recent research field, and some studies have demonstrated their potential in thermal dissipation into electronic devices. Eight ionenes obtained through Menshutkin reactions were synthesized and characterized. The analysis of the thermal tests allowed understanding of how the thermal properties of the polymers depend on the aliphatic nature of the dihalogenated monomer and the carbon chain length. The TGA studies concluded that the ionenes were thermally stable with T_10% above 420 °C. The DSC tests showed that the prepared ionenes presented solid–solid transitions, and no melting temperature was appreciated, which rules out the possibility of solid–liquid transitions. All ionenes were soluble in common polar aprotic solvents. The hydrophilicity of the synthesized ionenes was studied by the contact angle method, and their total surface energy was calculated. Self-healing behavior was preliminarily explored using a selected sample. Our studies show that the prepared ionenes exhibit properties that make them potential candidates for applications as solid–solid phase change materials.

In recent years, the utilization of extremophile microorganisms for the synthesis of metal nanoparticles, featuring enhanced properties and diverse compositions, has emerged as a sustainable strategy to generate high-quality nanomaterials with unique characteristics. Our study focuses on the biosynthesis of Cu-In-S (CIS) nanoparticles, which has garnered considerable attention in the past decade due to their low toxicity and versatile applications in biomedicine and solar cells. Despite this interest, there is a notable absence of reports on biological methods for CIS nanoparticle synthesis. In this research, three yeast species were isolated from soil samples in an extreme Antarctic environment—Union Glacier, Ellsworth Mountains. Among these isolates, Filobasidium stepposum demonstrated the capability to biosynthesize CIS nanoparticles when exposed to copper sulfate, indium chloride, glutathione, and cysteine. Subsequent purification and spectroscopic characterization confirmed the presence of characteristic absorbance and fluorescence peaks for CIS nanoparticles at 500 and 650 nm, respectively. Transmission electron microscopy analysis revealed the synthesis of monodisperse nanoparticles with a size range of 3–5 nm. Energy dispersive X-ray spectroscopy confirmed the composition of the nanoparticles, revealing the presence of copper, indium, and sulfur. The copper/indium ratio ranged from 0.15 to 0.27, depending on the reaction time. The biosynthesized CIS nanoparticles showed higher photostability than biomimetic nanoparticles and demonstrated successful application as photosensitizers in quantum dot-sensitized solar cells (QDSSC), achieving a conversion efficiency of up to 0.0247%. In summary, this work presents a cost-effective, straightforward, and environmentally friendly method for CIS nanoparticle synthesis. Furthermore, it constitutes the first documented instance of a biological procedure for producing these nanoparticles, opening avenues for the development of environmentally sustainable solar cells.

Overheating in miniaturized electronic devices can reduce their useful life, where conventional heat sinks are insufficient. The utilization of ionenes as solid–solid phase change materials is proposed to enhance thermal dissipation without the risk of leakage. In this work, a series of imidazolium ionenes with structural modifications in their aromatic core and aliphatic chain length were synthesized. The synthesis was carried out using the respective monomers diimidazole and alkyl dibromide, followed by counterion bromide exchange using lithium bis(trifluoromethanesulfonyl)imide, with yields over 90% in all cases. Thermal characterizations showed that all ionenes are heat-resistant, with degradation temperatures between 421 °C and 432 °C; moreover, they all presented only a solid–solid transition (Tg) as a phase change, between 59 °C and 28 °C, which varied depending on the aromatic core used and the length of the aliphatic chain. The obtained ionenes were introduced into an experimental device with an operating temperature of 40 °C, to be evaluated as solid–solid phase change materials in heat sinks. These demonstrated an average decrease in operating temperature of 9 °C compared to the device without ionenes. On the other hand, the stability of the ionenes was analyzed over 10 thermal cycles at 40 °C at a heating rate of 5 °C/min. This analysis demonstrated that the ionenes did not present changes or degradation during the evaluated cycles. These findings demonstrate that imidazolium ionenes are promising solid–solid phase change materials for use as efficient and self-repairing heat sinks in compact electronic devices.

This study explores the development and evaluation of a novel series of aromatic co-polyamides featuring diverse pendant groups, including phenyl and pyridinyl derivatives, designed for water desalination membrane applications. These co-polyamides, synthesized with a combination of hexafluoroisopropyl, oxyether, phenyl, and amide groups, exhibited excellent solubility in polar aprotic solvents, thermal stability exceeding 350 °C, and the ability to form robust, flexible films. Membranes prepared via phase inversion demonstrated variable water permeability and NaCl rejection rates, significantly influenced by the pendant group chemistry. Notably, pyridinyl-substituted membranes achieved water fluxes up to 17.7 L m⁻² h⁻¹ and a NaCl rejection of 37.3%, while phenyl-substituted variants provided insights into the interplay of hydrophobicity and porosity. These findings highlight the critical role of pendant group functionality in tailoring membrane performance, offering a foundation for further structural modifications to enhance efficiency in water treatment technologies.

The following study presents the initial evaluation (solubility, thermal stability, antibacterial activity, and cytotoxicity) of a series of previously described organic salts, derived from the bis(4-aminopyridinium) cation with different chain lengths, for their potential use as hospital disinfectants. Of the salts studied, those with chain lengths between 2 and 10 carbon atoms (C₂–C₁₀) showed high solubility in water, methanol, and DMSO. All salts exhibited high thermal stability, showing a thermal decomposition temperature (T_5%) above 330 °C. Antibiotic susceptibility testing of the studied E. coli, S. aureus, and S. typhimurium strains confirmed their resistance to different classes of commonly used clinical antibiotics, validating their selection. During the determination of antibacterial activity, the long-chain salts (C₁₀ and C₁₂) showed the greatest activity, with minimum inhibitory concentrations (MICs) from 31.2 μg/mL to 62.5 μg/mL in all the strains studied. Given the high activity of C₁₀ and C₁₂, their cytotoxicity was assessed in HeLa cells. They exhibited no cytotoxic effects after 12 h and only about 5% cytotoxicity after 24 h. Furthermore, the cell viability assay of the most active and water-soluble salt, C₁₀, showed that this salt can interact with the bacterial cytoplasmic membrane, increasing its permeability in both Gram-positive and Gram-negative bacteria. However, these results cannot rule out the possibility that this salt may have more than one site of action within the bacterial cell.