Layer-by-layer assembly often requires numerous deposition steps to obtain a suitable thickness for an effective flame retardant nanocoating. In an effort to make this technique more industrially feasible, an amine salt is added to the rinsing steps of a chitosan/sodium hexametaphosphate (CH/PSP) multilayered system to help facilitate thicker growing films with selfextinguishing capability and fewer processing steps. Cotton fabric coated with CH/PSP is rinsed in water baths containing tris(hydroxymethyl)aminomethane [THAM] and compared to control samples rinsed with deionized water. Only 10 bilayers of the CH/PSP system rinsed with THAM are required to achieve self-extinguishing behavior and pass a vertical flame test, while 15 bilayers of the control system are needed to achieve similar results.
Transparent polymeric thin films with high oxygen barrier are important for extending the shelf life of food and protecting flexible organic electronic devices. Polyelectrolyte/clay multilayer nanocoatings are shown to exhibit super gas barrier performance, but the layer‐by‐layer assembly process requires numerous deposition steps. In an effort to more quickly fabricate this type of barrier, a polyelectrolyte/clay coacervate composed of branched polyethyleneimine (PEI), poly(acrylic acid) (PAA), and kaolinite (KAO) clay is prepared and deposited in a single step, followed by humidity and thermal post‐treatments. When deposited onto a 179 µm poly(ethylene terephthalate) (PET) film, a 4 µm coacervate coating reduces the oxygen transmission rate (OTR) by more than three orders of magnitude, while maintaining high transparency. This single‐step deposition process uses only low‐cost, water‐based components and ambient conditions, which can be used to for sensitive food and electronics packaging.
Approximately one-third of the food produced in the world is not consumed, largely due to spoilage. Fresh fruits and vegetables have a shelf life of only a few days. To reduce spoilage, packaging with a high oxygen barrier is needed, but plastic packaging also creates waste. In this study, edible polyelectrolyte complexes consisting of chitosan (CH) and pectin (PT) are deposited onto fresh fruit to extend shelf life. This unique edible coating imparts a high gas barrier and high transparency that can slow the ripening of bananas and browning of apple slices. A 1.5 μm thick CH/PT coating reduces the oxygen transmission rate of a 179 μm polyester film by >10-fold. This single-step deposition process uses only water-soluble, edible biopolymers and ambient conditions, which is promising for reducing both food and packaging waste.
The lifespan of most organic electronics, and many types of food, depend on the oxygen and moisture barrier of the packaging materials. Despite exhibiting excellent oxygen barrier and being relatively easy to produce, polyelectrolyte multilayer nanocoatings (PEM) show limited moisture barrier. SiO x thin films can exhibit good moisture barrier, but rigidity that leads to cracking is a Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))
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