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The current open-loop practices employed to render paper substrates water- and oil-repellent for packaging and non-packaging applications have generated ocean pollution and have placed daunting burdens on landfills. In this study, we report a green, unique and facile approach for the fabrication of grease- and water-resistant paper products with 100% recyclability of the paper pulp. Low surface energy polydimethylsiloxane (PDMS) was grafted onto a biobased chitosan polymer via urea linkages to prepare the graft copolymer chitosan-graft-polydimethylsiloxane (chitosan-g-PDMS). Chitosan-g-PDMS was then applied as a coating onto an unbleached Kraft paper substrate from an aqueous solution. The coated paper substrates exhibited good hydrophobic properties with a water contact angle of 120.53 ± 0.96° and a Cobb 60 value of 9.89 ± 0.32 g m−2. The coated paper substrates also showed good oil-resistance as evident from the kit rating value of 11.7/12. The tensile strength, crushing resistance, bending stiffness, and internal tearing resistance of the paper before and after coating treatment was determined. Scanning electron microscopy (SEM) analysis was used to characterize changes in the porosity of the paper before and after the coating. The pulp recyclability of the coated paper was validated by subjecting the coated paper samples to repulping and washing treatment. This novel and practical approach can provide significant environmental benefits by offering plastic-free, fluorine-free and fully-recyclable water- and grease-resistant paper; thus promoting sustainability due to its unique closed-loop nature. [ABSTRACT FROM AUTHOR]

Conventionally, low-surface-tension fluorinated reagents are incorporated into anti-smudge (oil- and water-repellent) coatings for oil repellency. However, fluorinated compounds are expensive and an environmental concern because of their high stability and bioaccumulation. These factors limit their widespread application. We report herein the development of fluorine-free anti-smudge polyurethane coatings that are clear at thicknesses up to tens of micrometers and are able to sustain extensive surface damage. We demonstrate that these coatings can be applied readily onto a diverse range of substrates. [ABSTRACT FROM AUTHOR]

Clear anti-smudge coatings with a thickness of up to tens of micrometers have been prepared through a graft-copolymer-based approach from commercial precursors. The coatings repel water, diiodomethane, hexadecane, ink, and an artificial fingerprint liquid. In addition, they can be readily applied onto different substrates using different coating methods. These coatings could find applications in protecting hand-held electronic devices from fingerprints, windows from stains, and buildings from graffiti. [ABSTRACT FROM AUTHOR]

Clear anti-smudge coatings with a thickness of up to tens of micrometers have been prepared through a graft-copolymer-based approach from commercial precursors. The coatings repel water, diiodomethane, hexadecane, ink, and an artificial fingerprint liquid. In addition, they can be readily applied onto different substrates using different coating methods. These coatings could find applications in protecting hand-held electronic devices from fingerprints, windows from stains, and buildings from graffiti. [ABSTRACT FROM AUTHOR]

The cover page of the journal "Angewandte Chemie" is presented.