Tough and transparent polyurethane networks with self-healing capability at mild temperature conditions were successfully prepared in a 1-pot procedure. The self-healing ability of synthesized polyurethane comes from the covalent disulfide metathesis and non-covalent H-bonding.The mechanical testing indicates that disulfide metathesis reforms the covalent bonds on a longer time scale, while H-bonding gives rise to a healing efficiency of around 46% in the early healing processing. The compromise between mechanical performance and healing capability is reached by tailoring the concentration of disulfide. The tensile strength of the sample with 100% self-heal efficiency can get to 5.01 MPa, which can be explained by higher mobility of polymer chain under ambient temperature from creep testing. In order to increase the tensile strength of self-healing elastomer, the hydrogen bonding effect received attention. H-bonding is a kind of noncovalent self-healing trending force; the supermolecular selfhealing elastomer based on H-bonding interaction was firstly developed by Leibler and colleagues. 16,17 Other researchers also have similar reports. 18,19 Although the self-healing effect of H-bonding is limited, the contribution to the self-healing cannot be ignored.This work focuses on obtaining a material with good mechanical properties and self-healing in 1-pot method by adapting the disulfide concentration. The self-healing contribution of disulfide metathesis and H-bonding effect of this system were investigated. To the best of our knowledge, disulfide self-healing assisted H-bonding selfhealing materials have not been systematically studied.2 | EXPERIMENTAL | MaterialsPolytetramethylene ether glycol (PTMEG) with a number average molecular weight of 2000 g·mol −1 was provided by Aladdin IndustrialCorporation and was degassed for more than 3 hours at 90°C.

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Abstract:One promising application of photonics to astronomical instrumentation is the miniaturization of near-infrared (NIR) spectrometers for large ground-and space-based astronomical telescopes. Here we present new results from our effort to fabricate arrayed waveguide grating (AWG) spectrometers for astronomical applications entirely in-house. Our latest devices have a peak overall throughput of ∼23%, a spectral resolving power (λ/δλ) of ∼1300, and cover the entire H band (1450−1650 nm) for Transverse Electric (TE) polarization. These AWGs use a silica-on-silicon platform with a very thin layer of Si 3 N 4 as the core of the waveguides. They have a free spectral range of ∼10 nm at a wavelength of ∼1600 nm and a contrast ratio or crosstalk of about 2% (−17 dB). Various practical aspects of implementing AWGs as astronomical spectrographs are discussed, including the coupling of the light between the fibers and AWGs, high-temperature annealing to improve the throughput of the devices at ∼1500 nm, cleaving at the output focal plane of the AWG to provide continuous wavelength coverage, and a novel algorithm to make the devices polarization insensitive over a broad band. These milestones will guide the development of the next generation of AWGs with wider free spectral range and higher resolving power and throughput.

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We demonstrate a Complex Waveguide Bragg Grating (CWBG) which can be designed to generate an arbitrary transmission spectrum. A comprehensive design method, based on the Layer Peeling/Adding algorithm, is developed to realize the grating on a silica-on-silicon platform. The CWBG has a simple one-layer waveguide structure for ease of fabrication. A spectral precision better than ±0.1 nm and a suppression ratio between 15 dB and 33 dB are achieved for a transmission spectrum consisting of 20 randomly distributed spectral notches with a 3 dB width of 0.3–0.4 nm. Among the CWBG's various potential applications, we highlight its use for eliminating OH emission lines from the Earth's atmosphere for ground-based astronomical observations.

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Micro-sized ZIF-67 crystals were prepared and used as the reinforcing material to design novel paraffin-based composite phase change materials with a polymethyl methacrylate shell.

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