Preparation of a three-dimensional modified graphene oxide via RAFT polymerization for reinforcing cement composites

Defoaming and Toughening Effects of Highly Dispersed Graphene Oxide Modified by Amphoteric Polycarboxylate Superplasticizer on Oil Well Cement

The aggregation of graphene oxide (GO) during the hydration process limits its wide application. Polymer superplasticizers have been used to improve the dispersion state of GO due to their adsorption and site-blocking effects, though the formation of a large amount of foam during the mixing process weakens the mechanical properties of cement. A highly dispersed amphoteric polycarboxylate superplasticizer-stabilized graphene oxide (APC/GO) toughening agent was prepared by electrostatic self-assembly. Results demonstrate that the APC/GO composite dispersed well in a cement pore solution due to the steric effect offered by the APC. Additionally, the well-dispersed GO acted as an antifoaming agent in the cement since GO nanosheets can be absorbed at the air-liquid interface of APC foam via electrostatic interactions and eliminate the air-entraining effect. The well-dispersed APC/GO sheets promoted cement hydration and further refined its pore structure owing to the nucleation effect. The flexural and compressive strength of the cement containing the APC/GO composite were enhanced by 21.51% and 18.58%, respectively, after a 7-day hydration process compared with a blank sample. The improved hydration degree, highly polymerized C-S-H gel, and refined pore structure provided enhanced mechanical properties.

Controllable Regulation of Diesel Oil-in-Water Pickering Emulsion Stability by Multiresponsive Recyclable Magnetic Polymer Brush Microvessels

To ensure safety and efficiency in the production and transportation of fuel oil, there is an urgent demand to develop intelligent emulsifiers to deal with this challenge. Fe3O4@PDA-P(NIPAM-b-MAA-b-LMA) (MNPDNML) microspheres were prepared by modifying polydopamine and the triblock polymer brush P(NIPAM-b-MAA-b-LMA) on the surface of Fe3O4 nanoparticles via oxidative autopolymerization and SI-RAFT polymerization. Therefore, the MNPDNML microspheres exhibited sensitive stimulus-responsive behavior to pH, temperature, near-infrared (NIR) laser radiation, and magnetic fields. The stability state of the emulsion could be modulated by changing pH, temperature, magnetic field, and NIR radiation, and the reversible switching of emulsification/breaking behavior could be reached at least 10 times. This "intelligent emulsifier" exhibited high emulsification efficiency, long-term stability, and on-demand emulsification/breaking properties. It was notable that MNPDNML microspheres showed excellent emulsification ability for olive oil, kerosene, gasoline, and crude oil, which allowed the material to be widely used in the controlled transportation and separation of fuel oil.