Underwater adhesives with intrinsically tough and stable performance are urgently needed for environmental and engineering applications. Marine organisms have inspired numerous studies on the design and development of wet adhesives. Here we report a facile yet powerful strategy that recapitulates the delivery process of mussel adhesion for the development of strong and durable hydrogel adhesives. With the hydrogel matrix serving as an interfacial binding site, while the nanocrystal fillers contribute to the strong cohesion, they demonstrate outstanding adhesion abilities to a wide range of wet surfaces including aluminum, ceramics, glass, polymers and wood. Moreover, in contrast to commercial products for underwater bonding, the hydrogel adhesives present continuous strength growth instead of degradation with time due to the hydration effects and intrinsic reinforcement capabilities of ye'elimite. By synergistically combining macroscopic scale architectures and molecular level interactions, this in situ formation strategy opens a new route to incorporate nanocrystals into a hydrogel matrix, leading to a universal bonding solution on diverse surfaces underwater.

Temperature distribution in concrete is significant to the concrete structure’s macro properties and different factors affect the heat transfer in concrete, and therefore influence the temperature distribution. This work established a three-dimensional transient heat transfer model coupled with various environmental factors, using the finite element method for calculating the results and real-measured data for testing accuracy. In addition, a sensitivity evaluation of various factors was conducted. Due to various environmental factors, the results revealed that the prediction of temperature distribution in concrete by the three-dimensional model had great accuracy with an error of less than 4%. A particular hysteresis effect of temperature response in the concrete existed. Considering heat transfer in different spatial directions, the model can predict the temperature change of each spatial point instead of the spatial surface in different depths, proving the shortcomings of a one-dimensional heat transfer model. A greater solar radiation intensity caused a more significant temperature difference on the concrete surface: the surface temperature difference in July was twice as significant as that in December. Wind speed had a cooling effect on the concrete surface, and stronger wind speed accompanied with a stronger cooling effect made the surface temperature closer to the ambient temperature. Material properties had different effects on the temperature distribution of the surface part and internal part: the specific heat capacity determined the speed of the outer layer temperature change while the thermal conductivity determined the speed of the inner layer temperature change.

Correction for ‘Hydrogel networks as underwater contact adhesives for different surfaces’ by Pan Feng et al., Mater. Horiz., 2020, DOI: 10.1039/d0mh00176g.