SaBOX/Copper-Catalyzed Synthesis, Degradation, and Upcycling of a PMMA-Based Copolymer

Abstract

The development of sustainable vinyl polymers that can be chemically recycled or upcycled is highly required but very challenging. Herein, we report the efficient synthesis, degradation, and upcycling of a high-molecular-weight PMMA-based copolymer completely made of a C−C-bonded backbone enabled by the same catalytic system (SaBOX/copper) under mild conditions for the first time. The atom transfer radical copolymerization (ATRcP) of MMA with α-chloroacrylate is conducted at 30 °C by the catalyst, producing linear PMMA with C−Cl bonds, which are thermally stable below 200 °C with T g of 126 °C, exhibiting the thermophysical properties of commodity PMMA. At a higher temperature (≥65 °C), the catalyst could stimulate degradation at the position of the C−Cl bond, and the polymer chain is cleaved to give telechelic PMMA blocks with functional terminals. Remarkably, these blocks could be employed to readily prepare their parent copolymer, linear block copolymer, or novel branched block copolymer in the presence of a catalyst, realizing the chemical upcycling of a PMMA-based copolymer. Above all, catalysis plays a decisive role in these achievements, and strong catalyst effects are observed in the synthesis of degradable polymers, the degradation reactions, the structure of degradation products, and thus their upcycling. The SaBOX/copper catalytic system shows significant superiority over the copper catalysts commonly used in the literature.

Hydrophilic Poly(meth)acrylates by Controlled Radical Branching Polymerization: Hyperbranching and Fragmentation

“…The lower-than-expected molecular weights can be attributed to the β-carbon fragmentation of the POEOMA 500 backbone via formation of midchain radicals (MCRs) upon activation of C–Br bond (Scheme ). , The MCRs generated from C–Br bonds in the backbone of polyacrylates were sufficiently stable to synthesize graft/brush copolymers, whereas the polymethacrylates underwent fragmentation using ruthenium or photocatalysts. − …”

“…The lower-than-expected molecular weights can be attributed to the β-carbon fragmentation of the POEOMA 500 backbone via formation of midchain radicals (MCRs) upon activation of C−Br bond (Scheme 2). 77,78 The MCRs generated from C−Br bonds in the backbone of polyacrylates were sufficiently stable to synthesize graft/brush copolymers, 79 whereas the polymethacrylates underwent fragmentation using ruthenium or photocatalysts. 80−82 To investigate this under our polymerization conditions, two model copolymers of OEOMA 500 and OEOBA were synthesized using sodium pyruvate (SP)-reversible addition− fragmentation (RAFT) polymerization with different feed ratios of OEOBA (target DP of OEOBA = 12 and 24), yielding POEOMA 500 copolymers (P1−12 and P1−24) with midchain Br atoms (Figure 5).…”