Stable Free Radical Polymerization Research Articles

Stable Free Radical Polymerization of Styrene: Controlling the Process with Low Levels of Nitroxide

It is shown that the polydispersity and conversion in the stable free radical polymerization of styrene can be tuned by varying the 2,2',6,6'-tetramethylpiperidin-1-oxy/benzoyl peroxide ratio from 1.1:1 to 0.5:1. There is a self-correcting mechanism in the stable free radical polymerization of styrene that adjusts the number of growing chains and regardless of the initial initiator/nitroxide level the system moves toward and equilibrium concentration of free nitroxide

Characteristics of the Stable Free Radical Polymerization of Styrene in the Presence of 2-Fluoro-1-methylpyridinium p-Toluenesulfonate

The behavior of the stable free radical moderated polymerization of styrene in the presence of 2-fluoro-1-methylpyridinium p-toluenesulfonate (FMPTS) has been examined. The rate enhancement has been found to be the result of the decrease of free nitroxide (TEMPO) concentration that shifts the equilibrium between capped and growing chains toward the growing free radical form. The decrease in TEMPO concentration was shown to be coupled to the presence of FMPTS. The system is sensitive to the initiator employed and the timing of the addition of FMPTS. If the polymerization rate change due to the change in TEMPO concentration is accounted for, a secondary polymerization retarding influence of FMPTS was observed.

Narrow-Polydispersity Diblock and Triblock Copolymers of Alkyl Acrylates by a “Living” Stable Free Radical Polymerization

We have demonstrated the application of the stable free radical polymerization process to acrylates to produce high molecular weight homopolymers, mixed acrylate di- and triblock copolymers and acrylate/styrene diblock copolymers. Controlled propagation with retention of the living end group and cross-initiation of alkyl acrylates and styrene have also been demonstrated

Narrow Polydispersity Polystyrene by a Free-Radical Polymerization Process-Rate Enhancement

It is shown that the rate of polymerization of nitrixide-mediated stable free radical polymerization processes for styrene-based polymers and copolymers can be dramatically increased by the addition of camphorsulphonic acid (CSA). Very narrow polydispersity resins are obtained with CSA concentrations of 0.02 M or less, while larger amounts of CSA result in slight increases in polydispersity