A novel porous solid amine adsorbent (PEI@polyHIPE) with a highly interconnected pore network was prepared by high inner phase emulsion (HIPE) polymerization of styrene and divinylbenzene, and was simultaneously functionalized with high molecular weight (Mw = 70 000 Da) polyethylenimine (PEI). This proposed route requires fewer chemical reagents and less energy than conventional solid amine adsorbents that were prepared by amine post-modification such as chemical grafting and wet impregnation. The SEM image shows that a PEI layer was formed on the adsorbent's surface without damaging its original structure. And the CO2 adsorption capacity and pore structure of PEI@polyHIPE could be adjusted by adding different amounts of PEI. The one-step fabricated 4.0PEI70k@polyHIPE adsorbent showed a maximum adsorption capacity of 4.18 mmol CO2 per g-adsorbent at 20 °C under humid conditions. It obviously exhibited better CO2 adsorption performance, high amino utilization efficiency, and quick adsorption kinetics compared to PEI post-modification porous polystyrene (polyHIPE-PEI). This was attributed to its well-interconnected hierarchical structure, which could remarkably reduce gas diffusion resistance. Meanwhile, owing to the high-molecular-weight of PEI, the amount of amine loss could decrease during the process of adsorption/desorption, thus the adsorbent of PEI@polyHIPE showed promising regeneration performance. This one-step synthetic route provides a novel strategy for preparing amine functionalized adsorbents with high sorption capacity, amine efficiency, and regeneration stability.
Hydrogel hybrids are one of the key factors in life activities and biomimetic science; however, their development and utilization are critically impeded by their inadequate adhesive strength and intricate process. In nature, barnacles can stick to a variety of solid surfaces firmly (adhesive strength above 300 kPa) using a hydrophobic interface, which inspires us to firmly combine hydrogels and polymers through introducing an adhesive layer. By spreading a hydrophobic liquid membrane directly, tough combination of a hydrogel and a polymer substrate could be achieved after one-step polymerization. The fracture energy of the hydrogel attached to the surface of polyvinyl chloride was up to 1200 J m–2 and the tensile strength reached 1.21 MPa. Furthermore, the adhesion samples with this method exhibit an antifatigue performance, having withstood large bends and twists. It should be pointed out that this approach can also be applied to a variety of complicated surfaces. This work may expand the application range of hydrogels and provides an inspiration for hydrogel adhesion.
Flexible sensors for detecting strain have attracted the attention of many researchers. At present, it is an important research direction to prepare conductive hydrogels by adding different metal ions into hydrogels. In this study, a highly extensible and transparent ionic conductive hydrogel was prepared by one-step polymerization. Using sodium chloride as ionic conductive medium, interpenetrating network ionic conductive hydrogels with good flexibility, conductivity, and self-viscosity were constructed. The network is composed of graft copolymer polyacrylamide-acrylic acid (PAMAA) and biomass polymer sodium alginate (SA). Chemical and physical crosslinking have significant tensile properties for hydrogel. Because of the addition of sodium chloride, the hydrogel has excellent electrical conductivity. The SA/PAMAA-GL/NaCl conductive hydrogel can be adhered to different surfaces, such as glass, plastic, iron clip, copper sheet, and skin. The conductive hydrogel can be used as stress sensor, and the sensor is sensitive to the small strain and large strain. This conductive hydrogel has potential application prospects in flexible wearable electronic equipment, motion monitoring, medical rehabilitation, and other fields.
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