Research Focus
With this project, our goal is to take unfunctionalized, commercial PMMA and install the thermal trigger post-polymerization to allow for effective, catalyst-free depolymerization back to monomer. Our first aim is to explore the best conditions conducive to partially hydrolyzing the ester pendent groups of PMMA to poly(methyl methacrylate-co-methacrylic acid) using H2SO4. The next aim is to functionalize the partially hydrolyzed PMMA with N-hydroxyphthalimide, effectively installing the thermal trigger for depolymerization. Our final aim is to determine the extent of depolymerization of the unfunctionalized, hydrolyzed, and functionalized PMMA. We will use data from thermogravimetric analysis to determine the extent of depolymerization, and a bulk distillation will be performed to demonstrate the ability to recover highly pure methyl methacrylate.
Project Responsibilities
My contributions to the project included mechanically processing the commercial PMMA for hydrolysis, setting up functionalization and depolymerization reactions, and taking NMR and GPC samples. I also mentored two new undergraduates students on basic lab skills to train them to also be able to assist with this project.
Context
Poly(methyl methacrylate) (PMMA) is a commercial thermoplastic that is made by conventional radical polymerization with molecular weights of 105–106 g/mol. PMMA is widely used as a glass replacement due to its higher mechanical strength and lower density compared to glass [1]. It is prominent in the aircraft, automotive, and construction industries as well as orthopedics and dentistry [1,2,3]. Despite PMMA’s ubiquity, less than 10% of PMMA is recycled annually [1]. This presents an increased demand for sustainable methods to recycle it back to monomer in order to address the dramatic increase in plastic waste.
Two primary categories of polymer recycling include thermally reprocessing and chemical recycling. Thermally reprocessing commonly produces recycled polymers with reduced molecular weight and diminished mechanical properties [4,5]. Chemical recycling presents a way to degrade polymers back to monomer, which can then be repolymerized to create polymeric materials with identical mechanical properties [6]. However, the challenge of chemically recycling PMMA arises due to the stability of its all-carbon backbone [7]. Therefore, a robust, simple, scalable, and efficient strategy to depolymerize unfunctionalized PMMA would be beneficial both in academia and in industry.
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References
(1) De Tommaso, J.; Dubois, J.-L. Risk Analysis on PMMA Recycling Economics. Polymers 2021, 13, 2724.
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(2) Ali, U.; Karim, K. J. B. A.; Buang, N. A. A Review of the Properties and Applications of Poly (Methyl Methacrylate) (PMMA). Polym. Rev. 2015, 55, 678-705.
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(3) Jaeblon, T. Polymethylmethacrylate: Properties and Contemporary Uses in Orthopedics. J. Am. Acad. Orthop. Surg. 2010, 18, 297-305.
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(4) Maris, J.; Bourdon, S.; Brossard, J. M.; Cauret, L.; Fontaine, L.;
Montembault, V. Mechanical Recycling: Compatibilization of Mixed
Thermoplastic Wastes. Polym. Degrad. Stab. 2018, 147, 245−266.
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(5) Ragaert, K.; Delva, L.; Van Geem, K. Mechanical and Chemical
Recycling of Solid Plastic Waste. Waste Manage. 2017, 69, 24−58.
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(6) Jiang, J.; Shi, K.; Zhang, X.; Yu, K.; Zhang, H.; He, J.; Ju, Y.; Liu,
J. From Plastic Waste to Wealth Using Chemical Recycling: A Review.
J. Environ. Chem. Eng. 2022, 10, No. 106867.
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(7) Korpusik, A. B.; Adili, A.; Bhatt, K.; Anatot, J. E.; Seidel, D.;
Sumerlin, B. S. Degradation of Polyacrylates by One-Pot Sequential
Dehydrodecarboxylation and Ozonolysis. J. Am. Chem. Soc. 2023, 145,
10480−10485.