Self-Healing, Robust, Liquid-Repellent Coatings Exploiting the Donor-Acceptor Self-Assembly

Liquid-repellent coatings with rapid self-healing and strong substrate adhesion have tremendous potential for industrial applications, but their formulation is challenging. We exploit synergistic chemistry between donor-acceptor self-assembly units of polyurethane and hydrophobic metal-organic framework (MOF) nanoparticles to overcome this challenge. The nanocomposite features a nanohierarchical morphology with excellent liquid repellence. Using polyurethane as a base polymer, the incorporated donor-acceptor self-assembly enables high strength, excellent self-healing property, and strong adhesion strength on multiple substrates. The interaction mechanism of donor-acceptor self-assembly was revealed via density functional theory and infrared spectroscopy. The superhydrophobicity of polyurethane was achieved by introducing alkyl-functionalized MOF nanoparticles and post-application silanization. The combination of the self-healing polymer and nanohierarchical MOF nanoparticles results in self-cleaning capability, resistance to tape peel and high-speed liquid jet impacts, recoverable liquid repellence over a self-healed notch, and low ice adhesion up to 50 icing/deicing cycles. By exploiting the porosity of MOF nanoparticles in our nanocomposites, fluorine-free, slippery liquid-infused porous surfaces with stable, low ice adhesion strengths were also achieved by infusing silicone oil into the coatings

Precision covalent organic frameworks for surface nucleation control

Unwanted accumulation of ice and lime scale crystals on surfaces is a long-standing challenge with major economic and sustainability implications. Passive inhibition of icing and scaling by liquid-repellent surfaces are often inadequate, susceptible to surface failure under harsh conditions, and unsuitable for long-term/real-life usages. Such surfaces often require a multiplicity of additional features such as optical transparency, robust impact resistance, and ability to prevent contamination from low surface energy liquids. Unfortunately, most promising advances have relied on using perfluoro compounds, which are bio-persistent and/or highly toxic. Here it is shown that organic, reticular mesoporous structures, covalent organic frameworks (COFs), may offer a solution. By exploiting simple and scalable synthesis of defect-free COFs and rational post-synthetic functionalization, nanocoatings with precision nanoporosity (morphology) are prepared that can inhibit nucleation at the molecular level without compromising the related contamination prevention and robustness. The results offer a simple strategy to exploit the nanoconfinement effect, which remarkably delays the nucleation of ice and scale formation on surfaces. Ice nucleation is suppressed down to −28 °C, scale formation is avoided for >2 weeks in supersaturated conditions, and jets of organic solvents impacting at Weber numbers >105 are resisted with surfaces that also offer optical transparency (>92%)

Digital light 3D printing of a polymer composite featuring robustness, self-healing, recyclability and tailorable mechanical properties

Producing lightweight structures with high weight-specific strength and stiffness, self-healing abilities, and recyclability, is highly attractive for engineering applications such as aerospace, biomedical devices, and smart robots. Most self-healing polymer systems used to date for mechanical components lack 3D printability and satisfactory load-bearing capacity. Here, we report a new self-healable polymer composite for Digital Light Processing 3D Printing, by combining two monomers with distinct mechanical characteristics. It shows a desirable and superior combination of properties among 3D printable self-healing polymers, with tensile strength and elastic modulus up to 49 MPa and 810 MPa, respectively. Benefiting from dual dynamic bonds between the linear chains, a healing efficiency of above 80% is achieved after heating at a mild temperature of 60 °C without additional solvents. Printed objects are also endowed with multi-materials assembly and recycling capabilities, allowing robotic components to be easily reassembled or recycled after failure. Mechanical properties and deformation behaviour of printed composites and lattices can be tuned significantly to suit various practical applications by altering formulation. Lattice structures with three different architectures were printed and tested in compression: honeycomb, re-entrant, and chiral. They can regain their structural integrity and stiffness after damage, which is of great value for robotic applications. This study extends the performance space of composites, providing a pathway to design printable architected materials with simultaneous mechanical robustness/healability, efficient recoverability, and recyclability

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<span style="font-size:11.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-GB">Common bean (<i style="mso-bidi-font-style:normal">Phaseolus vulgaris </i>L<i style="mso-bidi-font-style:normal">., </i>Fabaceae), landraces of <i style="mso-bidi-font-style:normal">Lushai</i> hills in India: Nutrients and antioxidants source for the farmers</span>

313-320<span style="mso-ansi-language: EN-IN">Incredible diversity is found in the pod and seed morphology of the climbing type common bean landraces of Lushai hills of Mizoram, India. Twenty three such pole-type common bean landraces, consumed locally for seeds and pods, were collected from different districts of Lushai hills during 2008-13. Seeds were multiplied and evaluated for nutrients and antioxidant diversity. A significant diversity was found for seed N, P, K, Cu, Zn, Mn, Fe, ash content, total phenol, <span style="mso-ansi-language: EN-IN">diphenyl-2-picrylhydrazyl (DPPH) and azinobisethylbenzothiazoline-6-sulphonic acid (ABTS) radical scavenging activity. <span style="mso-ansi-language: EN-IN">Correlation analysis indicated numerous significant positive and negative correlations among nutrients. Principle component analysis (PCA) assessed the patterns of variation by taking all the nutrients variables together. The first four PCs accounted for 74% of the total variation. PC1 (26%) and PC2 (21%) showed the highest variability among all the PCs. Landraces MZFB-47, MZFB-41, MZFB-83, MZFB-116, MZFB-52, MZFB-28, MZFB-116 and MZFB-85 were found to be the most promising ones with highest N, P, K, Cu, Zn, Mn, Fe and ash content while, total phenol, DPPH and ABTS radical scavenging activity were found maximum in MZFB-97. The study generated information about the nutritional importance of this precious, yet unstudied diversity of landraces which can be conserved, promoted and utilized for selecting and improving superior nutritious common bean lines. </span