摘要：
Fluorocarbon-hydrocarbon hybrid cationic surfactants possess unique performance because they combine the characteristics of fluorocarbon and hydrocarbon surfactants, however, their potential as metal corrosion inhibitors has not been addressed. Here, two hybrid cationic surfactants (F4H6 and F6H6) were synthesized using perfluorobutylsulfonyl and perfluorohexylsulfonyl chains, respectively, through a cationic bridge of N-benzyl-N',N'-dimethyl ethylenediamine, to connect with a hexyl group as the hydrocarbon chain. Both F4H6 and F6H6 exhibited low critical micelle concentrations as 1.81 x 10(-3) and 3.76 x 10(-4) M and high aqueous surface activities with surface tensions as low as 22.07 and 1822 mN/m, respectively. Their anti-corrosion performance for carbon steel in 1.0 M HCl was demonstrated with inhibition efficiencies up to 92.7% and 95.8% at 15 x 10(-4) M by potentiodynarn ic polarization, similar to the results obtained by electrochemical impedance spectroscopy. Both surfactants belong to mixed-type inhibitors and adsorbed on carbon steel following the Langmuir isotherm model. Surface analyses by contact angle, SEM, and XPS revealed that F6H6 tended to form an adsorption layer more densely packed than F4H6 on carbon steel, more efficiently preventing corrosive species from corroding the metal. The results proved that such hybrid cationic surfactants can be utilized as promising metal corrosion inhibitors with the potential for wide applications. (C) 2020 Elsevier B.V. All rights reserved.
摘要：
Nano contrast agents (Nano CA) are nanomaterials used to increase contrast in the medical magnetic resonance imaging (MRI). However, the related relaxation mechanism of the Nano CA is not clear yet and little significant breakthrough in relaxivity enhancement has been achieved. Herein, a new hydrophilic Gd-DOTA complex functionalized with different chain length of PEG was synthesized and incorporated into graphene quantum dots (GQD) to obtain paramagnetic graphene quantum dots (PGQD). We performed a variable-temperature and variable-field intensity NMR study in aqueous solution on the water exchange and rotational dynamics of three different chain lengths of PGQD. The optimal GQD with paramagnetic chain length shows a great improvement in performance on (1)H NMR relaxometric studies. In vitro results demonstrated that the relaxivity of the designed PGQD could be controlled by regulating the PEG length, and its relaxivity was approximately 16 times higher than that of current commercial MRI contrast agents (e.g., Gd-DTPA), on a "per Gd" basis. The relaxivity of the Nano CA can be rationally tuned to obtain unmatched potentials in MR imaging, exemplified by preparation of the paramagnetic GQD with the enhanced T1 relaxivity. The fabricated PGQDs with suitable PEG length got the best relaxivity at 1.5 T. After intravenous injection, its feeding process by solid tumor could even be monitored by clinically used 1.5 T MRI scanners. This research will also provide an excellent platform for the design and synthesis of highly effective MR contrast agents.
摘要：
Fluorinated surfactants have comprehensive performance superior to non-fluorinated ones, however, their role as metal corrosion inhibitors is elusive. Herein, two fluorinated surfactants, one bearing a branched chain perfluoro group (BFIS) derived from hexafluoropropene trimer and the other bearing a straight chain perfluorohexanesulfonyl group (SFIS), were synthesized and comparatively investigated for their anticorrosion performance on carbon steel in HCI solution. Potentiodynamic polarization and electrochemical impedance spectroscopy revealed that BFIS possessed a corrosion inhibition efficiency much higher than SFIS (95.7% versus 86.6%), although both have similar minimum aqueous surface activities down to 18.50 mN/m. Surface analyses including contact angle, SEM, and XPS and theoretical calculation evidenced that BFIS formed a more densely packed adsorption layer than SFIS on carbon steel, more efficiently preventing corrosive species from corroding the metal surface. The results proved that by taking advantage of the branched chain perfluoro group as the hydrophobic part, fluorinated surfactants can be used as promising metal corrosion inhibitors with excellent performance. (C) 2019 Elsevier B.V. All rights reserved.
摘要：
Regioselective reactions with supramolecular control are of great interest. Herein, the pars-regiose-lectivity in the Mannich reaction of phenol with formaldehyde and dimethylamine was achieved with the use of beta-cyclodextrin (beta-CD), giving 4-(N,N-dimethylaminomethyl)phenol (p-AP) as major product. H-1 NMR and ITC measurements of the binding of beta-CD with the reactants and the products o- and p-AP revealed a new mechanism, in which beta-CD includes p-AP instead of phenol to control the reaction regioselectivity. This product-inclusion mechanism is remarkably different to the known reactant inclusion process. (C) 2017 Elsevier Ltd. All rights reserved.
通讯机构：
[Tu, HY; Zhang, AD] C;Cent China Normal Univ, Coll Chem, Minist Educ, Key Lab Pesticide & Chem Biol, Wuhan 430079, Hubei, Peoples R China.
摘要：
Catechol-containing polymers have attracted much attention in recent years because of their versatile mussel-inspired adhesive function. We report herein the facile synthesis of 4-/3-substituted catechols using the Mannich reaction of catechol with formaldehyde and secondary amines. The reaction proceeds smoothly in water without any catalyst. Separation of the desired products is important for the success of this methodology, and was achieved by a pH-controlled solvent extraction and recrystallization process. The synthesized functional catechols not only exhibited dopamine-like oxidative cross-linking, but also possessed functional groups that are useful for the synthesis of catechol-containing polymers. As a proof-of-concept application, two functional catechols, one bearing monohydroxyl and the other bearing dihydroxyl groups at the 4-aminomethyl substituent, were incorporated into polyacrylate and polyurethane backbones, respectively, endowing these polymers with excellent coatability on various surfaces.
摘要：
The invention discloses a fluorine-containing epoxy resin monomer, a prepolymer and preparation and application of an initiator for the fluorine-containing epoxy resin monomer. A hexafluoropropene trimer is used as a fluorine-containing precursor material, and is subjected to an etherification reaction with bisphenol A and epoxy chloropropane to prepare a hexafluoropropene trimer based bisphenol A epoxy resin monomer; the hexafluoropropene trimer is used as the fluorine-containing precursor material, and is subjected to a reaction with p-hydroxybenzyl alcohol or p-hydroxyphenethyl alcohol and formaldehyde to prepare a hexafluoropropene trimer based epoxy-phenolic resin prepolymer; the hexafluoropropene trimer is used as the fluorine-containing precursor material, and is subjected to etherification, bromation and quaternization with the p-hydroxybenzyl alcohol, carbon tetrabromide and substituted imidazole to prepare a hexafluoropropene trimer based benzylimidazole cationic initiator. The fluorine-containing epoxy resin monomer, the prepolymer and the initiator for the fluorine-containing epoxy resin monomer can be used for preparing a fluorine-containing epoxy resin coating material; an obtained coating is good in heat stability, has multi-level morphology, has excellent hydrophobic-oleophobic performance and fouling resistance, and can be applicable to the field of various coatings.
