Designing novel multifunctional materials from natural resources is a challenging goal that has increasingly attracted researchers. Recently, the great potential of silk fibers has been recognized. The target readers for this review are researchers from different backgrounds (i.e., non‐specialists in silk research) with special interests on the physical–chemical characterization of silk fibers, since their knowledge is crucial for the improvement of existent silk‐based biomaterials and the basis for the development of new products. Examples of usual applications of Bombyx mori silk fibers are given and some of the most recent and exciting progress in new technological fields, is presented.

Surgical adhesives have been used for several applications, including haemostasis, sealing air leakages and tissue adhesion. The aim of this work was to develop a biodegradable urethane-based bioadhesive containing free isocyanate groups. This material presents the advantage of being biodegradable, biocompatible and having the capacity of reacting with amino groups present in the biological molecules.A urethane based on castor oil (CO) was synthesized by reaction of the molecule with isophorone diisocyanate (IPD). The characterization of the material was accomplished by different techniques: ATR-FT-IR (attenuated transmittance reflection-Fourier transform infrared), swelling capacity determination, evaluation of the moisture curing kinetics, reaction with aminated substrates and determination of surface energy by contact angle measurement. The study of the urethane thermal properties was performed by DMTA (dynamical mechanical thermal analysis) and TGA (thermogravimetric analysis). The haemocompatibility of the urethane was also evaluated by thrombosis and haemolysis tests.

The effect of EuCl3 on the aggregation processes of sodium dodecyl sulfate was investigated. Electrical conductivity data, combined with Eu(III) luminescence measurements, suggest that the formation of micelles involving EuCl3 and SDS occurs at low SDS concentration; the formation of these mixed aggregates was also monitored by light scattering, which indicates that the addition of EuCl3 to SDS concentration at values below the critical micelle concentration of the pure surfactant results in a much higher light scattering than that found just with SDS micelles. It was also found that the Eu(III)/DS- complexes are formed with a binding ratio which varies between 20 and 4, depending on the initial concentration of Eu(III). As the concentration increases, turbidity occurs initially, but solutions become clear subsequently. In contrast to the behavior of SDS in the presence of aluminum(III), no flocculation was observed. From the analysis of electrical conductivity data and comparison with other systems, it is suggested that growth of aggregates happens, probably with formation of nonspherical systems. At the highest concentrations these may involve just Eu(III) and DS- ions. The effect of temperature on the SDS micellization process was studied. The calculated free energy of SDS micellization is not dependent on the initial EuCl3 but is dependent on the final balance between the presence of counterions in solution (ionic strength) and the temperature.

Electrochromic devices (ECDs) combining visible/near-infrared (NIR) transparent amorphous indium zinc oxide (a-IZO) external layers with innovative NIR-emitting electrolytes composed of red seaweed-derived κ-carrageenan (κ-Cg) polysaccharide, glycerol (Gly), and erbium triflate (ErTrif3·xH2O) are proposed as a valuable technological solution for the development of smart windows providing less heating demand, less glare and more indoors human comfort for the new generation of energy-efficient buildings. The electrolyte preparation is cheap, clean, and fast. The optimized sample including 50 wt% Gly/κ-Cg and 40 wt% ErTrif3·xH2O/κ-Cg exhibits the highest ionic conductivity (1.5 × 10–4 S cm–1 at 20 °C) and displays ultraviolet (UV)/blue and NIR emissions associated with the κ-Cg-based host and the Er3+ ions (4I15/2 → 4I13/2), respectively. The 5-layer configuration ECD tested demonstrated fast switching time (50 s), high electrochromic contrast (transmittance variations of 46/51% at 550/1000 nm), high optical density change (0.89/0.75 at 550/1000 nm), outstanding coloration efficiency (450th cycle = –15902/–13400 cm2 C–1 and +3072/+2589 cm2 C–1 at 550/1000 nm for coloration and bleaching, respectively), excellent electrochemical stability, and self-healing after mechanical damage. The ECD encompasses two voltage-operated modes: semibright warm (+3.0 V, transmittances of 52/61% at 550/1000 nm) and dark cold (−3.0 V, transmittances of 7/11% at 550/1000 nm).

Green electrolytes composed of kappa‐carrageenan (κ‐Cg), 1‐butyl‐3‐methyl‐1H‐imidazolium chloride ([Bmim]Cl) ionic liquid, and glycerol (Gly) are prepared in aqueous solution using a simple, clean, fast and low‐cost procedure. A flexible membrane incorporating 50% wt [Bmim]Cl and 50% wt Gly with respect to κ‐Cg exhibits the highest ionic conductivity values (8.47 × 10−4/2.45 × 10−3 S cm−1 at 20/66 °C, under anhydrous conditions, and 5.49 × 10−2/0.186 S cm−1 at 30/60 °C, at a relative humidity of 98%). Tests of room temperature air/hydrogen fuel cells incorporating κ‐Cg, κ‐Cg/Gly, and κ‐Cg/Gly/[Bmim]Cl membranes demonstrate that these predominantly protonic conductors electrolytes are particularly well suited for the design and fabrication of eco‐friendly electrochemical devices whose operation does not require the flow of gases and does not lead to water formation. These new materials have excellent application prospects in high performance (flexible) energy storage devices (supercapacitors and batteries) and electrochromic devices.