RESUMEN
Graphene oxide (GO) as a nano-reinforcing material has received extensive attention in cement composite materials. This paper employed molecular dynamics to simulate the friction process of calcium silicate hydrate (CSH) particles in the presence of double-sided and single-sided GCOOH (graphene oxide with a -COOH functional group, covering 10% of the surface). The investigation uncovered the lubricating effects of bifacial and unifacial GCOOH on the CSH interface. The findings indicate that the interfacial friction among CSH particles follows the sequence of double-sided GCOOH > pure CSH > single-sided GCOOH. In the double-sided GCOOH system, a greater external force is needed on the opposing side to alter the interaction with water molecules, calcium ions, and silica-oxygen tetrahedra, thereby enhancing friction. In contrast, the majority of the carboxyl groups on the single-sided GCOOH surface are strongly adsorbed onto the CSH surface, facilitating the entry of additional water molecules into the interlayer. Conversely, the unmodified side of the GCOOH has lower interactions with water molecules, hence improving its lubricating properties.
RESUMEN
Three-dimensional (3D) nanocomposite (NC) printing has emerged as a major approach to translate nanomaterial physical properties to 3D geometries. However, 3D printing of conventional NCs with polymer matrix lacks control over nanomaterial connection that facilitates maximizing nanomaterial advantages. Thus, a printable NC that features nanomaterials matrix necessitates development, nevertheless, faces a challenge in preparation because of the trade-off between viscosity and interfacial stability. Here, we develop viscoelastic Pickering emulgels as NC inks through jamming nanomaterials on interfaces and in continuous phase. Emulgel composed of multiphases allow a vast range of composition options and superior printability. The excellent attributes initiate NC with spatial control over geometrics and functions through 3D printing of graphene oxide/phase-change materials emulgel, for instance. This versatile approach provides the means for architecting NCs with nanomaterial continuous phase whose performance does not constrain the vast array of available nanomaterials and allows for arbitrary hybridization and patterns.
RESUMEN
Corrosion is a challenging problem for marine concrete infrastructure projects. In this study, an intelligent OH--regulated microcapsule is designed to prevent reinforcement corrosion, taking ethylcellulose (EC) as shell material and calcium oxide (CaO) as core material. X-ray computed tomography (XCT) is used to trace and contrast the corrosion profiles of the concrete reinforcement bar with and without the microcapsule. The results show that the OH--regulated microcapsule exhibits effective corrosion protection by delaying corrosion initiation and cracking. An SEM study revealed that the microcapsule could be broken as Cl- invades the concrete. However, intelligent OH- regulation was realized by releasing CaO.
RESUMEN
Efforts to develop microcapsules that respond to different stimuli derive from the incorporation of multiple dynamic assemblies of diverse functional species to the capsule shells. However, this usually involves complicated preparation processes that ultimately hinder the integration of multiple functionalities in a single material. This is addressed in the present work by proposing a multilevel interfacial assembly approach involving polymeric complexes that facilitate the fabrication of multistimuli-responsive microcapsules based on one-step Pickering emulsification using oppositely charged polycation-graphene oxide (GO) and polyanion-surfactant complexes prepared in immiscible liquid solutions. The complexes initially stabilize the emulsion based on electrostatic interactions. Subsequently, the highly dynamic bonding between the polymeric complexes facilitates the rearrangement of components at the oil/water interface to form a continuous interfacial shell membrane. The integrity of the microcapsule shells is sensitive to near-infrared irradiation owing to the GO component and is also sensitive to NaCl content because the assemblies between nanoparticles and polyelectrolytes are bonded through electrostatic interactions. The generality of the proposed strategy is demonstrated by the interfacial assembly of polycation-Fe3O4 complexes and polyanion-surfactant complexes. The resulting microcapsules exhibit salt responsiveness, pH responsiveness, and the ability to be positioned controllably by the application of an external magnetic field. This work provides a promising approach for the preparation of multistimuli-responsive microcapsules.
RESUMEN
Controlled release of hydrophobic agents from salt-responsive capsules is hindered by the hydrophilic shell and interfacial tension between inner oil and surrounding water. Rupturing shells in salt solution is another effective way. However, the densely entangled polyelectrolytes (PEs) in shells determined that the rupture requires extremely high ion-strength. Herein, salt-responsive capsules with double-network shells including a continuous PE-nanocrystal network and interfacial ion pairs are proposed and revealed via a one-step interfacial multilevel and multicomponent assembly (IMMA) method. Rigid nanocrystals can weaken the entanglements of PE chains and reduce the critical salt-concentration. Interfacial ion pairs are responsible for maintaining the stability of the shells. Such double networks enable the disintegration of capsules in an applicable salt-concentration without damaging the stability of capsules. In addition, hydrophobic domains assemblied by surfactants and PE-nanocrystal network supply transport pathway for oil to across hydrophilic shells and subsequently produce inverse micelle to carry oil into water. The mechanism of formation and release of capsules is systematically investigated, which further demonstrates IMMA to be a typical method for creation of sophisticated structures in a brief way.