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New Reactive Block Copolymers as Stabilizers in Emulsion Polymerization
Author(s) -
Tauer Klaus,
Zimmermann Arvid,
Schlaad Helmut
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20020101)203:2<319::aid-macp319>3.0.co;2-7
Subject(s) - polymer chemistry , copolymer , chemistry , ethylene glycol , emulsion polymerization , monomer , polymerization , styrene , stabilizer (aeronautics) , radical polymerization , organic chemistry , polymer , mechanical engineering , engineering
The synthesis and application of partly sulfonated polybutadiene‐ block ‐poly(ethylene glycol) copolymers as a new class of stabilizers for emulsion polymerizations is reported. These stabilizers combine all known stabilization mechanisms – electrostatic, steric, and electrosteric – together with the ability to participate in radical polymerization in a single molecule. It was found that the kind of initiator has a strong influence on the latex properties. Due to the polyelectrolyte nature of the new stabilizers, nonionic water‐soluble poly(ethylene glycol)‐azo‐initiators lead to smaller particles and less coagulum compared to water‐soluble ionic initiators. The investigations surprisingly revealed that the poly(ethylene glycol)‐azo‐initiators accumulate in the small‐particle‐size fraction due to side reactions leading to their incorporation. The efficiency of the new stabilizers in a radical emulsion polymerization of styrene is highest if the degree of sulfonation is between 20 and 40%. Compared to low molecular weight stabilizers like sodium dodecylsulfate, the reactive block copolymer stabilizers are much more efficient especially at stabilizer concentrations below 0.1% relative to the mass of monomer. The almost complete covalent binding of the reactive polymeric stabilizers to the particles is proved by a combination of ultrafiltration, elemental analysis, GPC, and FT‐IR investigations.