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Item type:Publication, Ulvan-based materials doped with lithium sulfate salts as solid biopolymer electrolytes for energy storage applications(Elsevier B.V., 2024-03-01)The conversion of algae biomass into high-value technological materials can promote the utilization of green algae and mitigate issues such as green tides and biofouling. This paper reports, for the first time, the utilization of ulvan in the production of solid biopolymer electrolytes (SBEs) doped with lithium sulfate salts. Ulvan were obtained from the green algae Ulva nematoidea using two different processing methods: hot water extraction and alkaline extraction. Hot water extraction enables the extraction of ulvan chains with a high molecular weight. In contrast, alkaline extraction produces a heterogeneous molecular weight distribution with Mw values of 730 kDa, 339 kDa, and 380 kDa. Frequency-dependent conductivity plots showed that SBEs made from ulvan extracted using the alkaline route featured higher conductivity than those SBEs made from water-extracted ulvan. The highest conductivity was obtained with ulvan extracted using the alkaline procedure, measuring 1.73 × 10−5 S/cm (tested at 10 MHz and 80 °C). The open conformation and low molecular weight of the ulvan extracted using the alkaline route would promote the segmental movement of ulvan chains and the mobility of Li+ ions. The results showed that ulvan can be used to produce solid-state electrolytes (SBEs) doped with Li-ion salt. The extraction procedure, Li-ion salt concentration, temperature, and frequency are essential variables that determine the conductivity of SBEs. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Exploring the Effects of Extraction Procedures on the Molecular Relaxation Processes of Ulvan Obtained from Ulva Papenfussii(Springer Science+Business Media, 2025-12-01)Ulvan, a biodegradable sulfated polysaccharide from Ulva papenfussii, was obtained using hot water (neutral pH) and alkaline (pH 13) methods to evaluate how extraction conditions modulate its molecular dynamics and dielectric behavior. While compositional changes due to extraction pH are well documented, their impact on the relaxation processes and segmental mobility of ulvan remains largely unexplored. Here, we provide a comprehensive characterization of dielectric permittivity and dielectric loss over a wide frequency (10⁻²-10⁶ Hz) and temperature range (-150 °C to 150 °C), supported by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The alkaline-extracted ulvan showed a lower glass transition temperature (31.6 °C vs. 47.9 °C), higher molecular mobility, and enhanced dielectric response. In contrast, the hot water-extracted sample exhibited greater thermal stability and a more defined dipolar relaxation processes, including a β-relaxation characterized using the Havriliak–Negami model. These findings suggest that hot water-extracted ulvan is more suitable for applications like biodegradable packaging or biomedical films, while alkaline-extracted ulvan is better suited for electroactive materials such as polymer electrolytes. This study highlights the role of extraction strategy in designing ulvan-based sustainable materials. The results underscore the relevance of broadband dielectric spectroscopy as a powerful tool for guiding the design of polysaccharide-based functional materials.3 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effects of morphology and extraction procedures on the chemical, thermal and dielectric properties of ulvan polysaccharides(Elsevier BV, 2025-09-01)This study presents the first comparative analysis of ulvan polysaccharides extracted from two morphologically distinct Ulva species native to the Peruvian coast: Ulvan papenfussii (blade-like) and Ulvan nematoidea (filamentous). Ulvans were extracted under two different conditions (pH 7 and pH 13) to investigate the combined influence of species-specific morphology and extraction methods on their physicochemical and molecular properties. Regardless of species or extraction conditions, all ulvan samples exhibited complex, multimodal molecular weight distributions, most notably in U. nematoidea. Extraction at pH 7 produced ulvans with higher sulfate contents, with U. nematoidea displaying the highest levels. Structural and chemical characterization via FTIR revealed distinct differences in sulfate positioning and uronic acid content between the species. Thermal analysis (DSC) indicated higher glass transition temperatures in U. nematoidea, likely due to its elevated sulfate content. Dielectric relaxation spectroscopy demonstrated that both taxonomic origin and extraction conditions significantly influence ulvan molecular dynamics. These findings, interpreted through Havriliak-Negami and Vogel-Fulcher-Tammann-Hesse modeling, underscore the importance of algal morphology and processing conditions in shaping the structure-property relationships of ulvans. The results offer new insights into tailoring ulvans for applications as functional bio-based polymers.2