The widespread use of fossil-derived polymers in flexible packaging has raised serious environmental concerns due to their poor recyclability, non-biodegradability, persistent pollution, and microplastic generation. This research demonstrated the development of high-performance paper-based packaging by utilizing fully bio-based coatings and laminates derived from nanofibrillated cellulose (NFC) and polyhydroxyalkanoates (PHAs). NFC hydrogels were produced from wood pulp, cotton noil, and hemp fiber using a carboxymethyl cellulose (CMC)-assisted high-pressure homogenization process, providing a scalable and green-chemical route to achieve highly fibrillated NFC for packaging applications. The resulting CMC adsorbed NFC exhibited specific surface areas of 300-380 m²/g with strong viscoelastic gel properties. Coatings based on NFC demonstrated excellent grease resistance (kit rating of 12) and reduced the WVTR of kraft paper from 6572.64 ± 294.43 to 4949.00 ± 218.61 g/m².day. Simultaneously, poly(3-hydroxybutyrate) (PHB) and its copolymers (PHBV, PHBHX, and PHB4HB) were formulated into 20 wt.% waterborne dispersions. These dispersions remained stable for at least 3 months and provided barrier coatings with WVTR values ranging from 400 to 740 g/m².day and a kit rating of 2-8. Additionally, to address NFC’s inherent moisture sensitivity, multilayer NFC/PHB laminated structures were fabricated. These laminates showed a WVTR of 571.85 ± 81.46 g/m².day and OTR values of 0.47 ± 0.02 and 1.27 ± 0.16 cc/100 in².day at 0% and 75% relative humidity, respectively, effectively preserving oxygen barrier performance under humid conditions. Overall, this work delivers a technically viable and environmentally friendly solution for replacing fossil-based materials with renewable paper-based packaging.
