RAFT Polymerization Procedure

Product Description

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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Reagents



RAFT Agent Catalog Number
2-Cyano-2-propyl benzodithioate 722987
4-Cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl]pentanoic acid 723274
Cyanomethyl methyl(phenyl) carbamodithioate 723002
4-Cyano-4-(phenylcarbonothioylthio) pentanoic acid 722995
2-Cyano-2-propyl dodecyl trithiocarbonate 723037
2-(Dodecylthiocarbonothioylthio)- 2-methylpropionic acid 723010
Cyanomethyl dodecyl trithiocarbonate 723029

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Precautions and Disclaimer

These products are for R&D use only, not for drug, household, or other uses. Please consult the Safety Data Sheet for information regarding hazards and safe handling practices.

Storage/Stability

723274 - Store the product at –20 °C and keep tightly closed. The product is light sensitive.

722995 and 723037 - Store the products at 2–8 °C and keep tightly closed.

722987, 723002, 723010, and 723029 - Store the products at 2–8 °C and keep tightly closed. The products are light sensitive.

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Procedures

Procedures of RAFT polymerization as performed by researchers at CSIRO.

  1. 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).
    1. Prepare stock solution of methyl methacrylate (15 mL, 0.14 mol) and AIBN (20.1 mg, 0.122 mmol) in 5 mL of benzene.
    2. 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.
    3. De-gas contents of ampules by three repeated freeze-evacuate-thaw cycles (0.05 mm Hg) and seal under vacuum.
    4. 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.


    RAFT Agent Polymerization Time Mn PDI % Conv. (NMR)
    722987 4 hours 8,468 1.14 24.5
    722987 15 hours 30,032 1.07 93.6
    723274 15 hours 25,959 1.08 98.5
     
    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



  2. 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).
    1. 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.
    2. De-gas contents of the ampule by three repeated freeze-evacuate-thaw cycles (0.05 mm Hg) and seal under vacuum.
    3. 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.


RAFT Agent Polymerization Time Mn PDI % Conv. (NMR)
723002 16 hours 16,400 1.25 91
 
Table 2Characteristics of poly(vinyl acetate) synthesized by RAFT polymerization.


Figure 2. GPC analysis of poly(vinyl acetate) polymerized for 16 hours using Catalog Number 723002 as a RAFT agent


Patents WO98/01478 and WO99/311444 Please see www.sigma-aldrich.com/raftlicense for license details.

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Materials

     
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