Researcher(s)
- Xiomaris Báez-Santiago, Chemical Engineering, University of Puerto Rico at Mayagüez
Faculty Mentor(s)
- Mary Watson, Department of Chemistry and Biochemistry, University of Delaware
- Pankti Mehta, Department of Chemistry and Biochemistry, University of Delaware
Abstract
Poly(methyl methacrylate) (PMMA) is a plastic used for a wide range of applications. Its production makes a worldwide impact, yet only 10% of the PMMA used is recycled, while the rest is landfilled or incinerated. As a result of this issue, there has been growing interest in recycling and upcycling polymer waste. Herein, we focused on the valorization via chemical modification of PMMA. Post-polymerization modification of PMMA has been achieved by hydrolysis to produce Poly(methacrylic acid) (PMAA), followed by subsequent photoredox mediated decarboxylative fluorination to yield PMAA-co-Polypropylene fluoride copolymer (PMAA-co-PPF). Hydrolysis of PMMA was successfully carried out using sulfuric acid. To find milder conditions for hydrolysis, we explored two methods: enzymatic catalysis and microwave irradiation. Enzymatic catalysis was carried out using the enzymes Resinase® and Novozym 435®. However, they were unable to yield positive results. The use of microwave irradiation was also investigated as an alternative approach to hydrolyze PMMA, but no results were detected using this method. Nonetheless, roughly 42% conversion was observed using the same conditions on the bench for 24 hours. Photoredox-mediated decarboxylative fluorination PMAA has been demonstrated using a wide range of organophotocatalysts including common dyes such as Eosin Y, Rose Bengal, and Riboflavin. This method is tunable by varying the quantity of fluorinating source, duration of irradiation, and the selected photocatalyst. Through these changes, PMAA-co-PPF copolymer with varying degrees of fluorination can be achieved. Two different irradiation sources were explored based on the absorption maxima of the photocatalyst and the best results were obtained using blue light irradiation. The highest degree of fluorination obtained was 69%. Future work involves optimizing microwave conditions, as well as enzymatic catalysis methods. The use of Photoacids will also be explored as an alternative method for hydrolysis.
Keywords: post-polymerization modification, PMMA, hydrolysis, enzymes, microwave irradiation, blue light