Department of Energy Engineering , Ulsan National Institute of Science and Technology (UNIST) , 50 UNIST-gil , Ulsan 44919 , Republic of Korea.
Research Center for Bio-Based Chemistry , Korea Research Institute of Chemical Technology (KRICT) , Ulsan 44429 , Republic of Korea.
ACS Nano. 2019 Apr 23;13(4):3796-3805. doi: 10.1021/acsnano.8b08522. Epub 2019 Mar 15.
Plastic packaging effectively protects foods from mechanical, microbial, and chemical damage, but oxygen can still permeate these plastics, degrading foods. Improving the gas barrier usually requires metallic or halogenated polymeric coatings; however, both cause environmental concerns and metallic coatings block visible light and electromagnetic signals. This paper reports a design of a highly flexible, visible light and radio frequency transparent coating on commercial poly(ethylene terephthalate) (PET) film. Nanoscale blending was achieved between negatively charged cellulose nanofibers and positively charged chitin nanowhiskers by employing spray-assisted layer-by-layer assembly. Synergetic interplay between these highly crystalline nanomaterials results in a flexible film with superior barrier characteristics. The oxygen transmission rate was below 0.5 mL m day. Moreover, this coating maintains its performance even when exposed to common hazards such as bending stress and hydration. The coating also notably reduces the haziness of PET with a negligible loss of transparency and provides effective inhibition of antibacterial growth. This "crab-on-a-tree" nanocoating holds high potential for biorenewable and optical and radio frequency transparent packaging applications.
塑料包装可以有效地保护食品免受机械、微生物和化学的损害，但氧气仍然可以渗透这些塑料，从而降解食品。提高气体阻隔性通常需要使用金属或卤化聚合物涂层；然而，这两种方法都会引起环境问题，而且金属涂层会阻挡可见光和电磁信号。本文报道了一种在商业聚对苯二甲酸乙二醇酯（PET）薄膜上制备高柔韧性、可见光和射频透明涂层的设计。通过喷雾辅助层层自组装，在带负电荷的纤维素纳米纤维和带正电荷的甲壳素纳米纤维之间实现了纳米级的共混。这些高结晶纳米材料的协同作用产生了具有优异阻隔性能的柔性薄膜。氧气透过率低于 0.5 毫升/米 2·天。此外，即使在弯曲应力和水合等常见危害下，这种涂层仍能保持其性能。该涂层还显著降低了 PET 的雾度，同时保持了透光率，并且对抑制细菌生长有显著效果。这种“蟹攀树”纳米涂层在生物可再生、光学和射频透明包装方面具有很大的应用潜力。
