The project aims to photochemically degrade non-hydrolyzable polymers such as polystyrene, poly(methyl methacrylate), and poly(vinyl chloride) using photochemical methods. These approaches utilize light’s efficiency in energy transfer, reducing the overall energy demand, which is a key issue in sustainable recycling. Photoinduced hydrogen atom transfer and halogen atom transfer reactions will be employed to achieve polymer degradation.

This project focuses on the photochemical degradation of polymers and copolymers composed of polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(vinyl chloride) (PVC), which are non-hydrolyzable and pose significant challenges to conventional recycling methods. Each polymer will be degraded through a mechanistically distinct pathway. PVC will be degraded using halogen atom transfer (XAT) reactions due to the presence of chlorine atoms in its structure, enabling radical generation through photochemical homolytic cleavage of C-Cl bond. PS, on the other hand, will be degraded via hydrogen atom transfer (HAT) reactions that exploit the reactivity of benzylic hydrogen atoms, which are susceptible to abstraction and subsequent backbone cleavage.

PMMA represents a more resistant case, as the hydrogen at the alpha-position is replaced by a methyl group, significantly reducing its susceptibility to conventional degradation pathways. To address this, various copolymerization strategies have been explored in the literature, including the incorporation of α-haloketone derivatives and thermally or photolytically cleavable pendant groups. While effective, these approaches often result in high material and production costs, posing a barrier to industrial scalability.

As a solution, this project proposes the copolymerization of PMMA with PS to utilize the benzylic hydrogen atoms of the PS segments to initiate degradation under photoinduced HAT conditions. This strategy aims to reduce costs while improving degradability, thus contributing to the development of a more sustainable and industrially feasible recycling method for traditionally recalcitrant polymeric materials.