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Fixing the greenhouse gas CO2 through epoxide helps to mitigate worldwide ecological troubles. The applications of metal‐free and solvent‐free catalysts remain a challenge for CO2 catalytic conversion. In this work, an array of quaternary ammonium salts derived from polyethyleneimine with hydroxyl groups ([PEI‐GDMAB‐Cn]Br) were constructed by the reaction of branched PEI with a molecular weight of 10000 and glycidyl alkyl dimethylammonium bromide. A range of experiments were designed to demonstrate that [PEI‐GDMAB‐Cn]Br can be considered as a valid metal‐free and solvent‐free homogeneous catalyst for the CO2‐epoxide cycloaddition reaction. Among of [PEI‐GDMAB‐Cn]Br, [PEI‐GDMAB‐C18]Br catalyzed the model reaction of CO2 and epichlorohydrin under optimized reaction conditions (T=80 °C, 1.0 atm CO2, catalyst 1 mol%, ECH 15 mmol, 16 h) and the conversion achieved at 97.5 %. Moreover, the catalyst exhibited stable reusability and broad substrate applicability, which was used in the following cycle succinctly, because of self‐separated properties by temperature control. The [PEI‐GDMAB‐C18]Br catalyzed reaction process was detected as a pseudo‐first‐order reaction after kinetic studies and an Ea was calculated to be 50.65 kJ/mol. A combinatorial catalytic mechanism of hydrogen bonding and bromide ions is suggested to explain the remarkable catalytic performance of this bifunctional catalyst. [ABSTRACT FROM AUTHOR]

Building the differential growth through the thickness is a promising and challenging approach to design the morphing structures of hydrogel actuators. Besides retaining the size of the hydrogel actuators under environmental stimuli still remains a big challenge. Herein, a facile and universal approach is developed to address both issues by introducing PEG during the polymerization of N‐isopropylacrylamide (NIPAm) via one step method using asymmetric mold. Both composition gradient and pore gradient are obtained in micro level along the thickness direction of the final hydrogel, while thin‐thickness gradient in macro level. The thickness gradient and water retention can be controllably adjusted by changing PEG concentration. The introduction of PEG effectively improves both responsive and non‐shrunken performance by the interaction with PNIPAm. The resultant anisotropic PNIPAm/PEG hydrogel respond quickly and reach maximum deformation (360°) within 10 s at low temperature (40 °C). The various 3D shape and biomimetic movement can be programmed by simply controlling the PEG concentration and mold shape. This strategy can provide new insights into the design intelligent soft materials with 3D morphing for bioinspired and biomedical applications. [ABSTRACT FROM AUTHOR]