| dc.description.abstract | Polymeric thin films with high oxygen barrier are important for extending the shelf life of food and protecting electronic devices. Polyelectrolyte complex (PEC) thin films impart super gas barrier, good adhesion, and low-cost processing. However, current PEC films fabricated via layer-by-layer assembly require numerous processing steps, which limits commercial applications. To deposit films with fewer deposition steps, PEC suspensions can be applied in a single step. This dissertation is focused on understanding, improving, and extending the utility of PEC-based gas barrier thin films.
A PEC coacervate composed of branched polyethyleneimine (PEI), poly(acrylic acid) (PAA), and kaolinite clay (KAO) was applied using bar-coating. The shear-induced alignment of a nano-brick wall structure lead to coatings that are less sensitive to humidity. PECs made with various molar ratios of PEI and PAA were prepared as one-pot coating solutions, which can be deposited via a simple dip-coating process and cured with a citric acid buffer solution. As-prepared conformal thin films impart excellent gas barrier, high modulus, and high moisture resistance. The strong complexation from ionic crosslinking creates an unusually dense thin film that is promising for various packaging applications. An edible PEC film consisting of chitosan (CH) and pectin (PT) was developed and deposited on bananas and apple slices. This edible coating slows the aging and browning of these fruits. The ability to extend the shelf life of fresh fruit and vegetables could reduce food waste. These direct-deposited PEC thin films have great potential for various gas barrier applications. | |
