Collaborative Research: Interfacial Phenomena of Functional Solutes Impregnated into Cellulose Packaging Substrates

Packaging is essential to everyday life. It protects our food and medicine and facilitates the safe transport of goods across the country and around the world. Plastics-based packaging has become popular because it offers better barrier properties than traditional paper-based packaging, which helps preserve the quality and safety of packaged products. Despite the benefits of plastic packaging, the poor end-of-life characteristics and recycling challenges often lead to environmental pollution. This research project seeks to develop a sustainable and functional paper-based alternative to plastic packaging that can be manufactured using renewable feedstocks and green chemistry technologies. Bio-based compounds extracted from agricultural waste will be impregnated into paper to improve the material’s functionality and barrier properties. The molecular-level interactions between paper and bio-based compounds will be examined to develop a competitive and sustainable alternative to plastic packaging. To increase diversity in STEM fields and promote economic prosperity, this project will engage high school, undergraduate, and graduate students from backgrounds and groups traditionally underrepresented in STEM fields. Additionally, outreach events will enhance public awareness of sustainable packaging practices. This project is jointly funded by the Interfacial Engineering program and the Established Program to Stimulate Competitive Research (EPSCoR). The research aims to develop next-generation sustainable packaging materials, with favorable performance and end-of-life characteristics, by engineering cellulosic substrates with improved barrier properties. This will be accomplished using the supercritical impregnation (SCI) methodology, where supercritical carbon dioxide (ssCO2) is used to impregnate bioderived solutes into cellulose matrices. The fundamental interfacial phenomena governing solute adsorption onto the cellulosic fibers will be determined. Two model solute systems – aliphatic and aromatic - and cosolvents have been chosen to represent the chemical species derived from agricultural residues. The aliphatic solute system is expected to yield desirable hydrophobic properties for the packaging material, and the aromatic solute system is expected to impart UV-absorbent properties. The initial adsorption kinetics of the solutes onto the cellulosic fibers will be measured using state-of-the-art quartz crystal microbalance (QCM-D) instrumentation and modeled to quantify the impact of the process conditions influencing rate constants. In operando near-infrared (NIR) spectroscopic studies will elucidate fundamental bonding and partitioning processes that facilitate SCI of paper substrates, including the hydrogen-bonding of interfacing cellulosic fibers, the influence of scCO2-cosolvent interactions on hydrogen-bonding, and the impact of scCO2-cosolvent-cellulose interactions on solute partitioning into cellulose. Lastly, relationships between solute diffusion mechanisms and the resultant distribution of solutes throughout cellulosic matrices will be evaluated via digital imaging analyses, with functional improvements assessed via contact angle and light transmittance measurements for the two systems, respectively. This research contributes to society in multiple ways, including developing sustainable packaging materials, advancing the potential of bioderived solutes as packaging additives, providing research opportunities for underrepresented students, and educating the community on sustainable packaging benefits through outreach events. 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.