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

该项目将开发一种新型高性能生物聚合物复合膜的制造原理，用于可持续和可生物降解的包装。以石油为基础的塑料，特别是以塑料包装膜的形式普遍存在的塑料，正在对环境和人类福祉造成连锁的负面影响。开发由丰富和可持续的原材料制成的合成塑料的可生物降解替代品是一项具有高度社会意义的重大科学挑战。该项目旨在使来自天然材料的薄膜的制造能够达到或超过普通合成聚合物薄膜的优异机械、渗透性和光学性能。值得注意的是，不仅材料，而且其制造，可以是环保的，因为整个过程，包括增强形成，然后薄膜挤出，将是水基的，容易和可伸缩的。因此，将在该项目中引入的原则可以通过促进向天然提取的可持续成分的转变来改变聚合物替代品的制造。这些可持续的包装材料已经引起了美国公司的兴趣，他们将能够评估这项新兴技术。该项目还将在可持续材料和生态友好和负责任的制造方面提供学生培训和更广泛的公众宣传和教育。通过这种方法生产的材料将作为高中和更广泛社区层面的动手活动和教育的基础。该项目将建立分级增强生物聚合物薄膜的制造基础。这些薄膜由PI实验室发现和开发的柔软树枝状胶体增强。柔软的树枝状胶体是由纳米纤维电晕包围的高度分枝的聚合物颗粒，由聚合物在湍流剪切介质中沉淀而成。它们是由壳聚糖制成的，具有很强的网络形成倾向，能够作为一种出色的增强材料。纤维在物理上相互连接，形成具有更高延展性和更低渗透性的增强网络。该项目将通过阐明壳聚糖软树枝状形成、纤维-基质相互作用、内部电荷中和和薄膜挤出的关键机制来建立制造原理。这将允许确定控制分层增强膜形成的控制参数，例如纤维形态和体积分数、电荷中和、亲水性和塑化。在解释了基质网络形成所涉及的相互作用和机制后，该团队将制定合理而高效的解决方案，以形成性能与目前包装材料相当或超过现有包装材料的薄膜，同时可按规模制造。因此，这项研究旨在揭示允许通过水基浇铸或挤出制造高性能生物聚合物薄膜的工艺和成分的关键参数。这项研究还将旨在证明这些过程的可扩展性和所产生的薄膜的生物降解性。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.