Cephalopods Inspired Rapid Self-Healing Nanoclay Composite Coatings with Oxygen Barrier and Super-Bubble-Phobic Properties

Abstract

Polymeric coatings with oxygen barrier properties are an important technology in food packaging that can extend the shelf life of food products and reduce waste. Although a typical technology in practical use is the deposition of metal or inorganic materials between multilayer films to reduce the oxygen transmission rate, once the film is damaged, oxygen permeates through the damaged area, damaging the packaged food. In addition, nanobrick wall structures consisting of nanoplatelet bricks have the potential to replace barrier films made of inorganic materials, however, they similarly lack repair performance or have slow repair speed despite having repair performance. Inspired by the rapid self-repair mechanism of cephalopods, the study develops a nanoclay-containing coating that can rapidly repair surface damage via water. By introducing CaCl<sub>2</sub>-derived counterions and montmorillonite for nanobrick wall structures into polyelectrolyte multilayers stacked by layer-by-layer self-assembly, the non-covalent polymer network is increased, resulting in mimicking a strong cephalopod-derived β-sheet structure and non-covalent intermolecular interactions derived from cephalopods. Regardless of the amount of montmorillonite added, the self-healing process was completed within 10 sec. The high-water retention at the surface showed super-bubble-phobicity in water and inhibited gas permeation. The oxygen permeability of the coatings with more than a certain amount of montmorillonite was less than 1/100 of that of bare polyethylene. The ultra-fast self-healing gas barrier coating has the potential to be used not only for food products but also for electronics and pharmaceutical packaging and gas separation applications. The key technology developed in this study provides novel insights into the construction of self-healing membranes made of composite materials and will contribute to the formation of a sustainable society.

Recent advances in self‐healing materials for food packaging

“…F I G U R E 3 Applications of selfhealing coatings in (A) pear, (B) apple, (C) apple slice, and (D) strawberry. 14,102,103,114 self-healing coating from (methacryloyloxy)ethyldimethyl-(3-sulfopropyl) (SBMA) and itaconic acid (IA). The self-healing process finished in 6 h at 25 C and 55% RH and was due to the reconstruction of hydrogen bonds in the damaged area.…”

“…The coating healed within 5 min under water stimulation and showed 97%, 95% and 63% recovery of tensile strength (19.89 MPa), oxygen transmission rate (4.78 ± 0.82 cm 3 /(m 2 d atm)), and water vapour transmission rate (40.56 ± 7.60 g/(m 2 d)) to those of intact coating, so it could diminish the effect of coating damage and remarkably retard the deterioration of packaged strawberries. Manabe et al 103 proposed a cephalopods‐inspired rapid self‐healing nanoclay composite coating with oxygen barrier and super‐bubble‐phobic properties. The LBL self‐assembly of branched PEI and PAA with the addition of CaCl 2 and nanoclay could mimic the strong structure of cephalopods and erase the surface scratches in 10 s. Especially, the existence of nanoclay led to the high water‐holding capacity, repelled the colliding bubbles in wet state, and improved the oxygen barrier property to less than 1/100 of that of bare polyethylene.…”

“…Applications of self‐healing coatings in (A) pear, (B) apple, (C) apple slice, and (D) strawberry 14,102,103,114 …”

Green Superlubricity Enabled by Only One Water Droplet on Plant Oil-Infused Surfaces

“…Excellent bioinspired materials with various functionalities, mimicking lotus leaves, 1,2 pitcher-plants, 3,4 spider silk, 5,6 cephalopods, 7,8 honeycomb, 9 amoeba, 10 and moth-eyes, 11,12 have broad scientific and technological implications in areas ranging from surface physicality to surface engineering. In particular, the development of "slippery" or "repellent" surfaces has motivated many researchers to explore innovative materials for both scientific and industrial applications owing to the challenges posed in our daily life by situations similar to nature.…”