Typical Procedures for Polymerizing via RAFT

Introduction

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 read the review by researchers at CSIRO.

Reagents

RAFT Agent

  • 2-Cyano-2-propyl benzodithioate (Product No. 722987)
  • 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (Product No. 723274)
  • Cyanomethyl methyl(phenyl) carbamodithioate (Product No. 723002)
  • 4-Cyano-4-(phenylcarbonothioylthio) pentanoic acid (Product No. 722995)
  • 2-Cyano-2-propyl dodecyl trithiocarbonate (Product No. 723037)
  • 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid (Product No. 723010)
  • Cyanomethyl dodecyl trithiocarbonate (Product No. 723029)

Storage/Stability

  • Product No. 723274 — Store the product at -20 °C and keep tightly closed. The product is light sensitive.
  • Product Nos. 722995 and 723037 — Store the products at 2-8 °C and keep tightly closed.
  • Product Nos. 722987, 723002, 723010, and 723029 — Store the products at 2-8 °C and keep tightly closed. The products are light sensitive.

Note: Please consult the Safety Data Sheet for information regarding hazards and safe handling practices.

RAFT Polymerization Procedures

  1. Methyl Methacrylate Polymerization: using methyl methacrylate (MMA, Product No. M55909) as the monomer, AIBN (Product No. 441090) as the initiator, and a RAFT agent (Product Nos. 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 Product No. 722987 (12.3 mg, 0.056 mmol) or Product No. 723274 (22.5 mg, 0.056 mmol). Note: Other glassware suitable for handling air sensitive reactions, such as a Schlenk reaction tube (Product No. 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.

Table 1. Characteristics of poly(methyl methacrylate) synthesized by RAFT polymerization

RAFT Agent Polymerization
Time
Mn PDI % Conv.
(NMR)
722987 4 hours 8468 1.14 24.5
722987 15 hours 30032 1.07 93.6
723274 15 hours 25959 1.08 98.5

 

  1. Vinyl Acetate Polymerization: using vinyl acetate (Product No. V1503) as the monomer, AIBN (Product No. 441090) as the initiator, and a RAFT agent (Product No. 723002).
  • Prepare solution of vinyl acetate (2.0 mL, 23.23 mmol), AIBN (2.0 mg, 0.012 mmol), and Product No. 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 (Product No. Z515981), may be used as an alternative to a sealed ampule.
  • De-gas contents of the ampule by three repeated freeze-evacuatethaw 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 and Figure 1.

 

Table 2. Characteristics of poly(vinyl acetate) synthesized by RAFT polymerization.

RAFT Agent Polymerization
Time
Mn PDI % Conv.
(NMR)
723002 16 hours 16,400 1.25 91

 

 

GPC analysis of poly(vinyl acetate) polymerized for 16 hours

Figure 1. GPC analysis of poly(vinyl acetate) polymerized for 16 hours using Product No. 723002 as a RAFT agent.

 

RAFT agents are sold for research purposes only: see Aldrich.com/raftlicense.

 

Materials List

     
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