The long and the short of radical polymerization

Precision functionality is the key feature of next-generation radical polymerization enabling the implementation of applications such as controlled drug delivery, self-healing material design, and optoelectronic materials. The incorporation of functionality is however diametrically opposed to diffusion-controlled growth-inhibiting termination reactions. The fundamental bottleneck remains the identification of a generic and flexible protocol to accurately map the short-long termination reactivity. Herein, we introduce a unique framework based on the reversible addition-fragmentation chain transfer-chain length dependent-termination (RAFT-CLD-T) method that encompasses an extension of state-of-the-art fundamental theories and a correction for possible polymer matrix effects. Applied to methyl methacrylate (MMA) polymerization, the short-long termination reactivity is accurately quantified for the first time. Data analysis reveals the deficiency of currently used simplified models to describe the true short-long termination reactivity and the dominance of short-chain diffusivity. The proposed framework and insights are a turnkey prerequisite for the fundamental understanding of radical polymerization processes and to complete current macromolecular diffusion theories. © 2015 American Chemical Society.