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Chain transfer agents

In radical polymerization, which is a typical process for obtaining polymers, the process in which a growing radical reacts with other substances within the polymerization system, and in which transfer and re-initiation of radicals also occur, is called the chain transfer reaction. The total number of radicals in the entire polymerization system does not change in an ideal chain transfer. When a chain transfer agent is used, new radicals are generated by receiving radicals from the growing polymer chain within the radical polymerization system. As a result, the growth of the polymer stops, but other growth reactions start, and the system tends to deliver polymers with uniform molecular weight, even though the molecular weight remains rather small. Our company offers a wide variety of efficient and representative thiol-based chain transfer agents.

Application example

  • Monomer emulsification synthesis
  • Water-soluble polymer synthesis

Polymerization test

We conducted a polymerization test on each chain transfer agent in emulsion polymerization using styrene, butyl acrylate, and methacrylic acid.。

Polymerization test results
Chain transfer agents sample name
BMMP
EHMP
MBMP
STMP
NDM
TDM
OTG
mol%Monomer
1.5
1.5
1.5
1.5
1.5
1.5
1.5
Mn
6,197
6,350
4,900
25,100
6,250
6,530
6,360
Mw
135,371
17,800
22,700
194,100
27,800
18,400
26,100
Mw/Mn
21.84
2.80
4.63
7.73
4.45
2.82
4.10

NDM:N-dodecyl mercaptan / TDM:Tert-dodecyl mercaptan / OTG:Octylthioglycolate

  • Conditions

    Emulsion polymerization

  • Temperature

    80℃

  • Monomer

    Styrene/n-Buthylacrylate/Methacrylic acid = 70/25/5

  • Emulsifier

    Dodecylbenzenesulfonic acid

  • Initiator

    Potassium persulfate (KPS)

Chain transfer constants

The experimental value for the chain transfer constant Cs of the chain transfer agent performance is described below. Since the Cs value is obtained by dividing the chain transfer rate constant Kc by the growth reaction rate Kp (Cs = Kc/Kp), it varies depending on the type of monomer, etc.

EHMP
MBMP
STMP
NDM
TDM
OTG
Styrene 60℃
13.1
13.8
12.6
13.0
13.6
12.9
MMA 60℃
1.39
1.49
1.22
1.36
1.25
1.21

MMA:Methyl methacrylate / NDM:N-dodecyl mercaptan / TDM:Tert-dodecyl mercaptan / OTG:Octylthioglycolate

Line up

BMPA

MPA-80

EHMP

MBMP

STMP

The values shown above are typical values,not guranteed values.

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