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2.
Nanomaterials (Basel) ; 12(3)2022 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-35159654

RESUMO

Nanolaminates are extensively studied due to their unique properties, such as impact resistance, high fracture toughness, high strength, and resistance to radiation damage. Varieties of nanolaminates are being fabricated to achieve high strength and fracture toughness. In this study, one such nanolaminate fabricated through accumulative roll bonding (Cu(16)/Nb(16) ARB nanolaminate, where 16 nm is the layer thickness) was used as a test material. Cu(16)/Nb(16) ARB nanolaminate exhibits crystallographic anisotropy due to the existence of distinct interfaces along the rolling direction (RD) and the transverse direction (TD). Nanoindentation was executed using a Berkovich tip, with the main axis oriented either along TD or RD of the Cu(16)/Nb(16) ARB nanolaminate. Subsequently, height profiles were obtained along the main axis of the Berkovich indent for both TD and RD using scanning probe microscopy (SPM), which was later used to estimate the pile-up along the RD and TD. The RD exhibited more pile-up than the TD due to the anisotropy of the Cu(16)/Nb(16) ARB interface and the material plasticity along the TD and RD. An axisymmetric 2D finite element analysis (FEA) was also performed to compare/validate nanoindentation data, such as load vs. displacement curves and pile-up. The FEA simulated load vs. displacement curves matched relatively well with the experimentally generated load-displacement curves, while qualitative agreement was found between the simulated pile-up data and the experimentally obtained pile-up data. The authors believe that pile-up characterization during indentation is of great importance to documenting anisotropy in nanolaminates.

3.
ACS Appl Mater Interfaces ; 13(48): 57851-57863, 2021 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-34843200

RESUMO

Magnetically directed localized polymerization is of immense interest for its extensive impacts and applications in numerous fields. The use of means untethered from an external magnetic field to localize initiation of polymerization to develop a curing system is a novel concept, with a sustainable, efficient, and eco-friendly approach and a wide range of potential in both science and engineering. However, the conventional means for the initiation of polymerization cannot define the desirable location of polymerization, which is often exacerbated by the poor temporal control in the curing system. Herein, the copper-immobilized dendrimer-based magnetic iron oxide silica (MNPs-G2@Cu2+) co-nanoinitiators are rationally designed as initiators for redox radical polymerization. The nanoinitiators are magnetically responsive and therefore enable localized polymerization using an external magnetic field. In this work, anaerobic polymerization of an adhesive composed of triethylene glycol dimethacrylate, tert-butyl peroxybenzoate, and MNPs-G2@Cu2+ as the magnetic co-nanoinitiators has been investigated. The use of a magnet locates and promotes redox free radical polymerization through the synergistic functions between peroxide and MNPs-G2@Cu2+ co-nanoinitiators. The mechanical properties of the resulting polymer are considerably reinforced because the MNPs-G2@Cu2+ co-nanoinitiators concurrently play another crucial role as nanofillers. This strategy provides a novel approach for magnetically tunable localized polymerization, which allows new opportunities to govern the formulation of advanced adhesives through polymerization under hazard-free conditions for various promising applications.

4.
Sci Adv ; 7(29)2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34261658

RESUMO

We rationally synthesized the thermoplastic and hydrophilic poly(urethane-acrylate) (HPUA) binder for a type of printable and stretchable Ag flakes-HPUA (Ag-HPUA) electrodes in which the conductivity can be enhanced by human sweat. In the presence of human sweat, the synergistic effect of Cl- and lactic acid enables the partial removal of insulating surfactant on silver flakes and facilitates sintering of the exposed silver flakes, thus the resistance of Ag-HPUA electrodes can be notably reduced in both relaxed and stretched state. The on-body data show that the resistance of one electrode has been decreased from 3.02 to 0.62 ohm during the subject's 27-min sweating activity. A stretchable textile sweat-activated battery using Ag-HPUA electrodes as current collectors and human sweat as the electrolyte was constructed for wearable electronics. The enhanced conductivity of the wearable wiring electrode from the reaction with sweat would provide meritorious insight into the design of wearable devices.

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