UV-initiated cationic frontal polymerization is exploited as a solvent-free, extremely fast, and low-temperature technique to obtain epoxy-based adhesives. Epoxy formulations are prepared by blending commercial resins at different weight ratios and adding photo and thermal initiators at different percentages. In addition, the influence of other critical parameters, including the joint thickness, the nature of the adherends, and the temperature, is studied. As the reaction front is thermally sustained, the boundary conditions play a key role during the curing process and heat dissipation through the adherends in particular. The thermal properties of the epoxy formulation are studied through differential scanning calorimetry analysis, and the joint strengths are investigated by carrying out single lap off-set shear tests under compression. The results demonstrate the feasibility of obtaining joints by means of the radical induced cationic frontal polymerization of the epoxy adhesives, which exhibit comparable epoxy group conversion and mechanical performances to the ones cured by traditional energy-intensive techniques. IntroductionEpoxy resins are widely used as high-performance adhesives and coatings in various fields, including the automotive, aerospace, and naval industries. [1][2][3] Traditionally, epoxy-based adhesives are thermally cured in the presence of hardeners, generally, amines or polyfunctional anhydrides, [4] to produce crosslinked thermoset structures characterized by good mechanical properties, good adhesion to the adherends, as well as thermal and chemical resistance. [5] However, thermal curing is a slow process and therefore requires a large amount of energy to maintain appropriate temperatures for the whole processing time. [6]

Environmentally friendly membranes with on-demand oil/water separation ability have recently received increasing attention in the application field of oily wastewater treatment. Herein, a facile and sustainable approach to prepare a flexible electrospun nanofiber/nanonet membrane using biodegradable polymers, chitosan (CS), and polycaprolactone (PCL) for controllable oil/water separation was demonstrated. The CS@PCL membranes are superamphiphilic, with both water and oil contact angles in air of 0°. The CS@PCL membrane shows underoil superhydrophobicity and underwater superoleophobicity. The membrane can effectively separate various oil/water mixtures, including immiscible oil/water mixtures and oil-in-water and water-in-oil emulsions by a simple prewetting approach. The obtained membrane exhibits a high separation efficiency of above 94.6% for immiscible light/heavy oil/water mixtures. Furthermore, the membrane shows excellent separation efficiencies for oil-in-water emulsions and water-in-oil emulsions, as above 99.9 and 94.5%, respectively.

The preservation of marine ecosystems is one of the most severe challenges at present. In particular, oil‐water separation from oil spills and oily wastewater is important. For this reason, a low‐cost, effective, and sustainable polymeric solution is in high demand. In this work, a controlled‐wettability membrane for selective separation of oil‐water mixtures and emulsions is developed. The nanofibrous membrane is prepared via a facile and cost‐effective electrospinning technique using environmentally sustainable materials, such as recycled polyethylene terephthalate and chitosan. The effect of different concentrations of chitosan on the morphology, chemical composition, mechanical properties, wettability, and separation performance of the membrane is evaluated. The membranes exhibited underoil superhydrophobic and underwater superoleophobic behavior, which is essential to perform the selective separation. In fact, the designed filter has competitive antifouling properties (oil intrusion pressure > 45 kPa) and showed high heavy‐ and light‐oil/water separation efficiencies (>95%) both for emulsions and immiscible mixtures.

A systematic microstructural characterization of alumina joined to Hastelloy C22® by means of a commercial active TiZrCuNi alloy, named BTi-5, as a filler metal is reviewed and discussed. The contact angles of the liquid BTi-5 alloy measured at 900°C for the two materials to be joined are 12° and 47° for alumina and Hastelloy C22® after 5 min, respectively, thus demonstrating good wetting and adhesion at 900 °C with very little interfacial reactivity or interdiffusion. The thermomechanical stresses caused by the difference in the coefficient of thermal expansion (CTE) between the Hastelloy C22® superalloy (≈15.3 × 10−6 K−1) and its alumina counterpart (≈8 × 10−6 K−1) were the key issues that had to be resolved to avoid failure in this joint. In this work, a circular configuration of the Hastelloy C22®/alumina joint was specifically designed to produce a feedthrough for sodium-based liquid metal batteries operating at high temperatures (up to 600 °C). In this configuration, adhesion between the metal and ceramic components was enhanced after cooling by compressive forces created on the joined area due to the difference in CTE between the two materials.