As a stacked form of ultrathin polymer films, multilayer nanostructures are of great interest in various applications. Coarse-grained molecular dynamics simulations were carried out to understand the behaviors of interfacial diffusion and bonding of multilayer polymer films. We found two obvious stages for the interfacial diffusion of polymers in the multilayer film, and it is 3 times faster in the first stage than in the second one due to the evolution of molecular conformations. The polymers near the interfaces have an in-plane mobility much higher than the out-of-plane one. The strength of interfacial bonding has been characterized by the fast tensile stress-strain curve along the normal direction. It shows multiple yielding points for the multilayer polymer films, which is distinct from the tensile behavior of the bulk. The ultimate tensile stress (UTS) and corresponding separating strain, surprisingly, do not necessarily increase with diffusion time. Because of the dramatic molecular rotation and extension during the first stage of interfacial diffusion, the interlayer interpenetration is nonuniformly distributed in the plane of the interface. Such a nonuniform distribution may be one of the reasons for the decrease of the UTS and separating strain.

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Steam generation through efficient utilization of solar energy is a promising technology in addressing the challenge of global freshwater shortage and water pollution. One of the biggest hurdles for traditional photothermal membranes to function continuously in a high temperature, high salt, and corrosive environment has been attributed to their rapid decline of mechanical properties. In this work, a highly efficient solar-driven interfacial water evaporation system has been developed via a polydopamine/carbon/silicon (PCS) composite membrane supported by a floating insulation foam substrate. A 3.1 fold increase in the water vaporization rate was recorded compared with the pure water system. The 2D-carbon nanolayer on the surface was successfully prepared by carbonizing low-cost linear polyethylene with a glass fiber (GF) membrane as the substrate, and then the carbon membrane was modified with dopamine to control water transport on the carbon coating and within the glass fiber. The PCS membrane has a high efficiency for solar steam generation owing to high optical absorption and has excellent solar thermal conversion capability. The evaporation rate and solar thermal conversion efficiency of the PCS membrane under simulated sunlight irradiation with 1 sun (1 kW·m–2) are 1.39 kg·m–2·h–1 and 80.4% respectively, which are significantly higher compared to GF membrane, carbon/silicon (CS) membrane, and pure water without a photothermal membrane. The water evaporation system retained high efficiency after 20 cycles under simulated sunlight irradiation of 1 sun. This study provides critical insight on the design and fabrication of a highly efficient and durable evaporation system.

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In this work, expandable graphite (EG)/thermoplastic polyurethane (TPU) composites with excellent exfoliation, dispersion and two-dimensional plane orientation of the EG fillers were manufactured by microlayer coextrusion technology.