Abstract
Various types of controlled/living radical polymerizations, or using the IUPAC recommended term, reversible-deactivation radical polymerization (RDRP), conducted inside nano-sized reaction loci are considered in a unified manner, based on the polymerization rate expression, Rp = kp[M]K[Interm]/[Trap]. Unique miniemulsion polymerization kinetics of RDRP are elucidated on the basis of the following two factors: (1) A high single molecule concentration in a nano-sized particle; and (2) a significant statistical concentration variation among particles. The characteristic particle diameters below which the polymerization rate start to deviate significantly (1) from the corresponding bulk polymerization, and (2) from the estimate using the average concentrations, can be estimated by using simple equations. For stable-radical-mediated polymerization (SRMP) and atom-transfer radical polymerization (ATRP), an acceleration window is predicted for the particle diameter range, . For reversible-addition-fragmentation chain-transfer polymerization (RAFT), degenerative-transfer radical polymerization (DTRP) and also for the conventional nonliving radical polymerization, a significant rate increase occurs for . On the other hand, for the polymerization rate is suppressed because of a large statistical variation of monomer concentration among particles.
Highlights
With the advent of reversible-deactivation radical polymerization (RDRP), the characteristics of living polymerization can be introduced to radical polymerization, creating novel possibilities to produce well-defined polymers, such as narrow distributed, end-functionalized, block, star, and dendritic polymers
In reversible-addition-fragmentation chain-transfer polymerization (RAFT) it is not required to reduce the frequency of bimolecular termination, and the pseudo-livingness is attained if an active radical is transferred to a large number of chains before being stopped by bimolecular termination
The threshold diameter below which the polymerization rate increases significantly by reducing the particle size,R, for degenerative-transfer radical polymerization (DTRP) and the conventional nonliving free-radical polymerization, where the intermediate PXP does not exist, can be determined with. Another characteristic particle diameter may exist for RAFT, together with DTRP and the conventional nonliving free-radical polymerization (FRP), below which the miniemulsion polymerization rate may become smaller than that predicted by using the average concentrations [23]
Summary
With the advent of reversible-deactivation radical polymerization (RDRP), the characteristics of living polymerization can be introduced to radical polymerization, creating novel possibilities to produce well-defined polymers, such as narrow distributed, end-functionalized, block, star, and dendritic polymers. When the conventional nonliving free-radical polymerization is conducted in a dispersed system, typically for Dp < 100 nm, the polymerization rate increases significantly by reducing the particle size. The threshold diameter below which the polymerization rate increases significantly by reducing the particle size ,R , for DTRP and the conventional nonliving free-radical polymerization, where the intermediate PXP does not exist, can be determined with. May exist for RAFT, together with DTRP and the conventional nonliving free-radical polymerization (FRP), below which the miniemulsion polymerization rate may become smaller than that predicted by using the average concentrations [23].
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