Stirring of the sulfuric acid and cotton solution to produce nanocellulose

Author: Zane Mebruer | Major: Mechanical Engineering | Semester: Fall 2023

Beginning in the Fall 2023 semester, I worked with Dr. Wan Shou of the Mechanical Engineering department on a materials science project that concerned the creation of biodegradable composites that utilized nanocellulose. The goal of the project is to create a biodegradable alternative to popular, environmentally destructive petroleum-based polymers, namely Styrofoam. There are three main objectives of the project:  to synthesize the required nanocellulose from commercially available cotton, distributing the created nanocellulose within a biodegradable polymer matrix, and testing the composite’s mechanical and thermal properties. These properties will then be compared to the properties of the biodegradable polymer matrix and to the properties of Styrofoam to see the effects of nanocellulose on the biopolymer and if the created composite can mimic the ideal properties of Styrofoam.  This semester I mainly worked on setup of the project and nanocellulose synthesis.

I chose this project because I wanted to pursue a minor in nanotechnology for a future career, meaning I needed to engage in a nanotechnology-based research project, and because alternative biodegradable materials have always been a fascination of mine. While the possibility of discovering a perfect new material was unlikely, through the process I could learn more about working with nanoscale materials, something that I had yet to experience, and I could set the groundwork for future research possibilities within the field. I originally found my mentor, Dr. Wan Shou, by asking him about research opportunities while I was in his Materials class my sophomore year. I had already been working with Dr. Wan Shou for about a year on a soft robotics research project when I first conceptualized this project.  Dr. Shou had a multitude of experience in materials research, so it was an easy choice to work with him as my research mentor.

When beginning my research project, there was a good deal of necessary setup required. This project was unlike any that had been performed in Dr. Shou’s lab previously, so I had to procure many pieces of equipment, some of which I had to wait for longer than I had anticipated, setting back my research. Once I had everything I needed,  I faced some additional complications regarding the synthesis procedure of the nanocellulose. One of the crucial steps in the procedure I used was acid hydrolysis of the commercially available cotton utilizing sulfuric acid. This step broke down the large cellulose chains within the cotton into exponentially smaller cellulose segments, eventually breaking the cotton down to the nanometer scale that I desired. The complications regarding this step were due to the fact I needed to use heavily concentrated sulfuric acid, an incredibly dangerous chemical that I had little experience with. For the purposes of the experiment I had to dilute the acid to a 50% weight ratio with water, which is a very reactive process that produces toxic steam. This meant I needed to perform the experiment within an enclosed fume hood, which Dr. Shou did not have in his lab. After some searching within the department, Dr. Uche Wejinya graciously allowed us to use the fume hood in his lab.

Once the experiment could be performed in a safe area with all the necessary materials, Dr. Shou assisted me in creating my first batch of nanocellulose. There were some minor hiccups in the synthesis process due to my inexperience with some of the equipment, but in future trials those will be easily ironed out. As I continue with my research next semester, I plan to first create further batches of nanocellulose, and attempt to get it SEM scanned to verify that it is truly nanoscale. After I have a good starting amount of synthesized nanocellulose, I’ll begin distributing it within some different biodegradable polymers, namely PLA, TPS, and PEF. Once I have created a composite material, I’ll test the materials’ mechanical properties through a tensile test, and thermal conductance using a guarded hot plate test. If time allows, I’d also like to test the composite materials’ impact strength using a Charpy Impact test, and water resistance using a water mass absorption test. Overall, I’ve highly enjoyed the research experience that this grant has provided to me thus far and I am excited to continue my research into next semester.