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Polymerisation with VPA und VPADME practically free of residual monomers |
In suitable solvents, VPA and VPADME undergo radical polymerization with common initiators at mild temperatures (75–120 °C).
Preferred VPA comonomers are acrylates and derivatives with which VPA can be mixed and polymerized without difficulty. The less reactive methacrylates and styrene are other options.
Just as the monomer is readily compatible with a variety of solvents, copolymers can likewise be produced in a broad range of solvents. The selection of the specific solvent depends on the VPA content and the polarity of the comonomers used: it may vary greatly, ranging from water to THF to toluene.
Suitable initiators include azo compounds such as V65 [2,2’-azobis(2,4-dimethylvaleronitrile)] or peroxo starters like tert-butylperoxypivalate.
The choice of the solvent is largely determined by the percent-age of highly hydrophilic VPA contained in the copolymer.
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VPA and VPADME are compatible with various solvents and have excellent solubility characteristics. |
- Polymers containing less than 10 % VPA can be obtained in conjunction with non-polar comonomers, such as butyl acrylate, in non-polar solvents like toluene, butyl acetate or methylisobutylketone.
- Polar solvents like THF, butanol, dimethyl carbonate should be used for higher VPA levels up to about 30 %.
- VPA levels exceeding 30 % also require high-polarity solvents, from THF to lower alcohols such as isopropanol, ethanol or even methanol.
The molecular weights that can be obtained depend on the reaction conditions, solvents and comonomers and are commonly in the 10-50 kDa range.
The polymerization reaction can be optimized to ensure that the polymers obtained are practically free of residual monomers.
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