(18b) Spray-Coated Multilayer Cellulose Nanocrystal – Chitin Nanofiber Films for Barrier Applications
AIChE Annual Meeting
2018
2018 AIChE Annual Meeting
Separations Division
Bioinspired Membranes and Membrane Processes
Sunday, October 28, 2018 - 3:49pm to 4:08pm
Chitin is an abundant biopolymer whose natural production is second only to cellulose. Similar to cellulose nanocrystals (CNCs) or nanofibers (CNFs), chitin nanofibers (ChNFs) can be isolated and used as sustainable O2 barrier materials for food, electronics and pharmaceutical packaging. The difficulty in melt processing chitin and cellulose nanomaterials presents an obstacle to their incorporation in packaging. Alternatively, these bio-available nanomaterials are readily dispersed in water, and spray coating is a versatile technique allowing uneven, or delicate surfaces to be coated at high rates. In the present study we demonstrate the successful layer-by-layer spray coating of cationic ChNF and anionic (CNC) suspensions onto poly(lactic acid) (PLA) films. ChNF/CNC multilayers were found to lead to a reduction in the O2 permeability of the final composite film by as much as 73 % with the largest effects seen in composites with three alternating layers (ChNF-CNC). Multilayer ChNF/CNC coatings were found to have lower O2 permeability and lower haze than those coated with ChNF or CNCs alone (72 % and 86 % lower haze respectively), pointing to a synergistic effect. The composites had a water vapor transmission rate similar to the PLA substrate.