Direct conversion of CO2 to polymers, such as polyurea, is an effective approach for CO2 capture and utilization. However, traditional methods involving CO2 and diamine polymerization require high pressures and temperatures (>5 MPa, ∼180 °C) and result in low molecular weight polyurea. A method has been developed to synthesize polyurea directly from CO2 at mild temperature and pressure (0.1–0.5 MPa, 15–90 °C) in a one-step reaction using organic superbases as both catalysts and dehydrants with the formation of DBU-H2O. This process allows for fast polymerization (10–30 min) and yields high molecular weight polyurea (>106 g/mol). The tensile strength of the as-prepared polyurea film reaches 13.5 MPa, which indicates excellent mechanical properties.
Jingjing Zhou,Changqing He,Lin He,Xincheng Zhang,Ying Tian,Hong Sui,Xingang Li
Emerging nano-demulsifiers are efficient functional materials for separating emulsions. However, the size effects of nanoparticles on demulsification and the mechanisms of enhanced demulsification by nano-modification are still unclear. Herein, a nano-demulsifier (SiO 2 -mANP) was prepared by modifying carboxyl-modified aliphatic nonionic polyether (mANP) with nano-SiO 2 . Compared to single polyether, the SiO 2 -mANP significantly reduced the demulsification temperature from 60 °C to room temperature . The demulsification efficiency of the asphaltene-stabilized water-in-oil emulsion reached 91.0% within 10 min at room temperature (dehydration over 99.5% in less than 2 min at 60 °C). The size effects study showed that smaller SiO 2 -mANP nanoparticles (∼10 nm) performed better in demulsification due to their superior diffusion ability in continuous phase and greater adsorption at the oil-water interface. The electrostatic potential (ESP) and independent gradient model (IGM) were used for the first time to analyze the changes in non-covalent interactions between demulsifiers and water. Nano-modification facilitated the formation of more non-covalent interaction sites, notably hydrogen bonding sites such as silanol groups. This rearranged the molecular surface ESP of the demulsifier. As a result, the non-covalent interactions between demulsifier and water were greatly enhanced, leading to a significant reduction in the coalescence time of water droplets. This primary study on the size effects and non-covalent interactions of nano-demulsifiers will provide guidance for the design and development of highly efficient demulsifiers.
危险品化学品经营许可证（带存储）