Understanding depolymerization kinetics of poly(butyl methacrylate) using flow chemistry

Area of Science:

• Polymer Chemistry
• Chemical Engineering
• Materials Science

Background:

• Reversible addition-fragmentation chain-transfer (RAFT) depolymerization enables efficient chemical recycling of polymers.
• Continuous flow processes with inline dialysis can accelerate depolymerization.
• Kinetic understanding is crucial for optimizing flow-based polymer recycling.

Purpose of the Study:

• To determine the kinetics of RAFT depolymerization under continuous flow conditions.
• To investigate the influence of temperature and polymer concentration on depolymerization rates.
• To identify rate-limiting steps in flow RAFT depolymerization with inline dialysis.

Main Methods:

• Studied RAFT depolymerization of poly(butyl methacrylate) (polyBMA) in a continuous flow system.
• Varied depolymerization temperatures between 120 °C and 160 °C.
• Analyzed the dependence of depolymerization rate on initial polymer concentration and compared it with dialysis clearance rates.

Main Results:

• Determined the activation energy for RAFT depolymerization to be 79.5 kJ mol⁻¹.
• Observed a square root dependence of the depolymerization rate on initial polymer concentration.
• Identified the in-flow membrane dialysis as the rate-determining step, significantly slower than depolymerization.

Conclusions:

• The dialysis step is the bottleneck in continuous flow RAFT depolymerization with inline dialysis.
• Increasing the cross-flow rate in dialysis accelerates monomer removal.
• Optimizing dialysis conditions is essential for efficient flow-based polymer recycling using RAFT.