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The synthesis of CuAu-based monometallic (MNPs) and bimetallic nanoparticles (BNPs) supported on chitosan-based hydrogels for their application as catalysts is presented. The hydrogels consisted of chitosan chains cross-linked with tripolyphosphate (TPP) in the form of beads with an approximate average diameter of 1.81 mm. The MNPs and BNPs were obtained by the adsorption of metallic ions and their subsequent reduction with hydrazine, achieving a metallic loading of 0.297 mmol per gram of dry sample, with average nanoparticle sizes that were found between 2.6 and 4.4 nm. Both processes, metal adsorption and the stabilization of the nanoparticles, are mainly attributed to the participation of chitosan hydroxyl, amine and amide functional groups. The materials revealed important absorption bands in the visible region of the light spectra, specifically between 520 and 590 nm, mainly attributed to LSPR given the nature of the MNPs and BNPs inside the hydrogels. Subsequently, the hydrogels were evaluated as catalysts against the reduction of 4-nitrophenol (4NP) into 4-aminophenol (4AP), followed by UV–visible spectroscopy. The kinetic advance of the reaction revealed important improvements in the catalytic activity of the materials by synergistic effect of BNPs and plasmonic enhancement under visible light irradiation, given the combination of metals and the light harvesting properties of the nanocomposites. Finally, the catalytic performance of hydrogels containing BNPs CuAu 3:1 showed an important selectivity, recyclability and reusability performance, due to the relevant interaction of the BNPs with the chitosan matrix, highlighting the potential of this nanocomposite as an effective catalyst, with a potential environmental application.

The development of biobased resins for 3D printing has gained importance in recent years, driven by urgent environmental issues confronting our planet. The derivatives of biobased glycerol represent a promising alternative to fossil fuels, holding a central position in the field of polymer synthesis. In this background, polyglycerol-based acrylic monomers were synthesized by Sakamoto Yakuhin Kogyo Co., Ltd. (Osaka, Japan). These monomers, which include acrylic groups, are sensitive to UV light, and hence can be processed via photopolymerization and VAT polymerization techniques. Reactivity and rheological properties of the monomers were studied. Further, carbon nanotubes (CNTs) were added in different weight percentages to investigate the electrical conductivity properties. Finally, the formulations incorporating CNTs were processed via a Digital Light Processing (DLP) 3D printer for an assessment of their printability.

Bimetallic CuPt alloyed nanoparticles were conveniently synthesized on biohydrogels and were capable of carrying out hydrogen release from ammonium borane hydrolysis. The biohydrogel consisted of bead-shaped alginate chains crosslinked by calcium ions, which were used as support material to synthesize and stabilize the bimetallic nanoparticles, employing adsorption and coreduction strategy steps. The as-prepared nanoparticles exhibited light absorption in the visible range (580 nm) resulting from the surface plasmon resonance (SPR) phenomenon ascribed to the presence of copper in the alloyed system. On the other hand, the presence of platinum atoms in these nanoalloys endows them with a notable catalytic performance toward ammonia borane hydrolysis as a hydrogen release reaction, reaching kr values from 0.32 × 10−4 to 2.23 × 10−4 mol L−1 min−1 as the Pt content increases. Finally, by taking advantage of the SPR light absorption shown by CuPt 1:1, it was demonstrated that these entities could be successfully employed as photocatalysts for the hydrogen generation reaction, boosting its activity by almost 2.06 times compared to its performance in dark conditions. This catalytic enhancement was mainly ascribed to the light-harvesting properties promoted by plasmonic effects and the specimen's metallic composition.

This work presents the synthesis of new poly(itaconate)s containing one or two nitrile pendant groups through conventional radical polymerization. To the best of our knowledge, this is the first time in which the synthesis of poly(itaconate)s containing nitrile groups is reported in the literature. The effect of nitrile groups on the main properties is analyzed. Polymer structures were confirmed by Fourier transform infrared spectroscopy (FTIR), 1H and 13C NMR. Molecular weights were measured by size exclusion chromatography (SEC), while thermal characterization was achieved by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Dielectric properties were measured using broadband dielectric spectroscopy at different temperatures. Polymers with one or two nitrile groups presented dielectric constant values (at 25 °C and 1 kHz) of around 7 and 12.5, respectively, with relatively low dielectric losses with values below 0.02. BDS measurements showed notorious sub-glass transitions attributed to the movement of the dipolar groups under the electric field, even below −100 °C, allowing to achieve dielectric constant values above the average for polymers even at extremely low temperatures. Therefore, these materials could be considered as good candidates for energy storage applications.

This work presents the synthesis and characterizaiton of three new poly(itaconate)s containing nitriles functional groups as high dipole moment entities and three different cycloalkyl pendant groups, in order to increase the rigidity of the system and therefore, their dipolar glass polymer temperature interval. The structural, thermal and dielectric characterization has been carried out in terms of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS), respectively. All polymers showed good thermal properties with degradation temperatures above 250 °C, presenting higher glass transition temperatures than those of recently reported poly(itaconate)s. Regarding dielectric properties, dielectric constant values between 4.0 and 4.3 (at 25 °C and 1 kHz) and relative low loss tangent values (below 0.01) were obtained. BDS measurements showed in all cases, notorious sub-glass transitions even at temperatures below −100 °C, resulting in a broad temperature interval in which these polymers could work without high dielectric losses. Therefore, these materials seem to be good candidates for dielectric applications such as energy storage, among others.

Fourth generation polyamidoamine dendrimer (PAMAM, G4) modified with fluorescein units (F) at the periphery and Pt nanoparticles stabilized by L-ascorbate were prepared. These dendrimers modified with hydrophobic fluorescein were used to achieve self-assembling structures, giving rise to the formation of nanoaggregates in water. The photoactive fluorescein units were mainly used as photosensitizer units in the process of the catalytic photoreduction of water propitiated by light. Complementarily, Pt-ascorbate nanoparticles acted as the active sites to generate H2. Importantly, the study of the functional, optical, surface potential and morphological properties of the photosensitized dendrimer aggregates at different irradiation times allowed for insights to be gained into the behavior of these systems. Thus, the resultant photosensitized PAMAM-fluorescein (G4-F) nanoaggregates (NG) were conveniently applied to light-driven water photoreduction along with sodium L-ascorbate and methyl viologen as the sacrificial reagent and electron relay agent, respectively. Notably, these aggregates exhibited appropriate stability and catalytic activity over time for hydrogen production. Additionally, in order to propose a potential use of these types of systems, the in situ generated H2 was able to reduce a certain amount of methylene blue (MB). Finally, theoretical electronic analyses provided insights into the possible excited states of the fluorescein molecules that could intervene in the global mechanism of H2 generation.

This work presents the synthesis of new poly(itaconate)s containing sulfone or nitrile pendant groups through conventional radical polymerization together with their characterization and comparison with poly(methacrylate)s containing identical groups. Structural and thermal characterization has been carried out in terms of Fourier transform infrared spectroscopy, differential scanning calorimetry, nuclear magnetic resonance, and thermogravimetric analysis. Characterized by broad band dielectric spectroscopy (BDS), all polymers showed dielectric constant values between 7 and 10 (at 25 °C and 1 kHz) and relative low dielectric loss values (≈0.02). BDS measurements showed, for all the polymers analyzed, notorious subglass transitions even at temperatures below −100 °C, resulting in a broad temperature interval in which these polymers exhibit high dielectric constant and could work without high losses. Therefore, these materials seem to be good candidates for dielectric applications such as energy storage, among others.