CAS: Novel Principles of Fabricating High-Performance Sustainable Packaging Films from Hierarchically Reinforced Biopolymers

This project will develop the manufacturing principles of a new class of high-performance biopolymer composite films for applications in sustainable and biodegradable packaging. Petroleum-based plastics, particularly ubiquitous in the form of plastic packaging films, are causing cascading negative impacts on the environment and human well-being. The development of biodegradable alternatives for synthetic plastics made from abundant and sustainable raw materials is a major scientific challenge of high societal importance. The project aims to enable the manufacturing of natural-material-sourced films that could match or exceed the excellent mechanical, permeability and optical properties of common synthetic polymer films. Notably, not only the material, but also its manufacturing, can be environmentally friendly, as the whole process, including the reinforcement formation, followed by film extrusion, will be water-based, facile and scalable. Thus, the principles that will be introduced in this project could transform the manufacturing of polymer substitutes by facilitating a shift to naturally derived sustainable constituents. These sustainable packaging materials have already evoked interest from US companies, which will be able to evaluate this emerging technology. This project will also provide student training and broader public outreach and education in the topics of sustainable materials and ecologically-friendly and responsible manufacturing. The materials produced by this method will serve as an basis for hands-on activities and education at high school and broader community levels. The project will establish the manufacturing fundamentals of hierarchically reinforced biopolymer films. These films are reinforced by the soft dendritic colloids discovered and developed in the PI’s laboratory. The soft dendritic colloids are highly branched polymeric particles surrounded by a nanofibrillar corona that are manufactured by polymer precipitation in a turbulently sheared medium. They are made of chitosan, have a strong propensity for network formation and are able to serve as an outstanding reinforcement material. The fibrils interlink physically to create reinforcing networks with increased ductility and reduced permeability. The project will establish the manufacturing principles by elucidating the key mechanisms involved in chitosan soft dendricolloid formation, fibril-matrix interactions, internal charge neutralization and film extrusion. This will allow determination of the governing parameters that control the formation of the hierarchically reinforced films, such as fibrillar morphology and volume fraction, charge neutralization, hydrophilization and plasticization. After interpreting the interactions and mechanisms involved in the matrix-network formation, the team will formulate rational and efficient solutions to the formation of films with properties comparable to or exceeding the ones of present packaging materials, while being manufacturable to scale. Thus, the research aims to reveal the key parameters of the process and composition that allow for manufacturing of high-performance biopolymer films by water-based casting or extrusion. The research will also aim to prove the scalability of these processes and the biodegradability of the resulting films. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.