Unravelling the effect of side chain on RAFT depolymerization; identifying the rate determining step

Area of Science:

• Polymer Chemistry
• Chemical Recycling
• Materials Science

Background:

• Reversible addition-fragmentation chain-transfer (RAFT) depolymerization offers low-temperature chemical recycling for near-quantitative monomer regeneration.
• Key mechanistic aspects, particularly the influence of polymer structure on kinetics, require further elucidation.

Purpose of the Study:

• To investigate the effect of pendant side chains on RAFT depolymerization kinetics.
• To identify the rate-determining step in the RAFT depolymerization process.

Main Methods:

• Systematic variation of side chain length (number of carbons and ethylene glycol units) in methacrylates.
• Addition of radical initiators during depolymerization of poly(methyl methacrylate) and poly(hexyl methacrylate).
• Computational modeling to assess fragmentation energetics.

Main Results:

• Depolymerization rate significantly accelerated with increasing side chain length.
• Radical initiator addition led to rate equilibration, confirming chain activation as rate-determining.
• Computational studies showed energetically favorable chain-end fragmentation for longer side chains.

Conclusions:

• Side chain structure critically influences RAFT depolymerization rates.
• Chain activation is the rate-determining step in RAFT depolymerization.
• Findings enable the design of more efficient and tailored depolymerization systems.