RAFT (Reversible Addition-Fragmentation chain Transfer) is a form of living radical polymerization involving conventional free radical polymerization of a substituted monomer in the presence of a suitable chain transfer (RAFT) reagent. Use of the appropriate RAFT agent and polymerization conditions allows for the synthesis of polymers with low PDI and high functionality. For a further explanation of RAFT technology and its advantages, please visit sigmaaldrich.com/materialmatters to see Material Matters Vol. 5, No 1 on Modern Polymerization Techniques.
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Procedures of RAFT polymerization as performed by researchers at CSIRO.
Methyl Methacrylate Polymerization - using methyl methacrylate (MMA, Catalog Number M55909) as the monomer, AIBN (Catalog Number 441090) as the initiator, and a RAFT agent (Catalog Number 722987 or 723274).
Prepare stock solution of methyl methacrylate (15 mL, 0.14 mol) and AIBN (20.1 mg, 0.122 mmol) in 5 mL of benzene.
Aliquot 2 mL samples of stock solution into ampules containing Catalog Number 722987 (12.3 mg, 0.056 mmol) or Catalog Number 723274 (22.5 mg, 0.056 mmol). Note: Other glassware suitable for handling air sensitive reactions, such as a schlenk reaction tube (Catalog Number Z515981), may be used as an alternative to a sealed ampule.
De-gas contents of ampules by three repeated freeze-evacuate-thaw cycles (0.05 mm Hg) and seal under vacuum.
Polymerize by placing sealed ampule in heated oil bath (60 °C) for 15 hours.
Researchers at CSIRO have tested select Aldrich RAFT agents in the polymerization of methyl methacrylate and analyzed the resulting polymers. The data are presented in Table 1.
Table 1. Characteristics of Poly(methyl methacrylate) synthesized by RAFT polymerization.
Figure 1. NMR of poly(methyl methacrylate) polymerized for 15 hours using Catalog Number 722987 as a RAFT agent
Vinyl Acetate Polymerization - using vinyl acetate (Catalog Number V1503) as the monomer, AIBN (Catalog Number 441090) as the initiator, and a RAFT agent (Catalog Number 723002).
Prepare solution of vinyl acetate (2.0 ml, 23.23 mmol), AIBN (2.0 mg, 0.012 mmol), and Catalog Number 723002 (26.64 mg, 0.12 mmol) in an ampule. Note: Other glassware suitable for handling air sensitive reactions, such as a schlenk reaction tube (Catalog Number Z515981), may be used as an alternative to a sealed ampule.
De-gas contents of the ampule by three repeated freeze-evacuate-thaw cycles (0.05 mm Hg) and seal under vacuum.
Polymerize by placing sealed ampule in heated oil bath (60 °C) for 16 hours.
Researchers at CSIRO have tested select Aldrich RAFT agents in the polymerization of vinyl acetate and analyzed the resulting polymer. The data are presented in Table 2.
