Polystyrene Laboratory Analysis: A Hands-On Experience to Determine the Molecular Weight of Polystyrene Through Spin Casting in A University Laboratory Setting

Hands-on learning is a staple in high school science education, as it provides students with a fast-learning curve and a great degree of field competency. However, due to the safety risks associated with high school students in university chemistry laboratory settings, high school students rarely engage in authentic hands-on chemical learning. To bridge the gap between the benefits and drawbacks, this study investigates a method to educate high school students (with no previous experience) about standard chemical laboratory practices. 98 high school students experimented throughout two days to determine the molecular weights and characteristics of various polystyrene samples, essential knowledge for polymer recycling. Students were split into 5 groups so that laboratory usage be organized and staggered. After laboratory safety training was administered, students created different types and concentrations of toluene-based samples and spin casted these samples onto silicon wafers, determining thickness through ellipsometry. With the data, each group calculated molecular weight, propagated error, and wrote laboratory reports. In order to evaluate the extent of learning through this process, students were given pre-training and post-experimentation assessments with the same questions pertaining to laboratory safety, equipment usage, and materials science related topics. On average, students displayed scores 63% higher on the post-experiment assessment compared to those of the pre-training assessment. The results suggest the experience not only taught students about the various materials science concepts, but also improved their laboratory logic. Therefore, our method is recommended to be implemented at the university level for motivated high school and first-year undergraduate students.