Product Bulletin Coatings / Paints / Additives / Adhesives VeoVa™ Monomers Characteristics and Reactivity Parameters VeoVa 9 monomer and VeoVa 10 monomer represent a family of vinyl ester monomers with a unique, high- VeoVa 9 and 10 are monomers with many similarities. Their main characteristics are as follows: ■ ly branched, carbon-rich structure. Their principal use is as modifying comonomers in vinyl and acrylic polymerisation. Typical properties and specifications are listed in their respective product data sheets. ■ A branched tertiary structure with bulky and hydrophobic hydrocarbon groups. This provides the monomers with a very low surface tension and a hydrophobic nature. As a consequence, the monomers possess a strong resistance to saponification. Furthermore, VeoVa monomers do not degrade under the influence of UV light. Reactivity: VeoVa monomers polymerise with various other comonomers through reaction of their vinyl ester functional group. In this way, the specific properties of the VeoVa monomers can be imparted to their copolymers. CH 3 O C CH 2 CH O C R1 R2 Structure of VeoVa monomers where R1 and R2 are (branched) alkyl groups containing 6 or 7 carbon atoms for VeoVa 9 and 10 monomers respectively. Vinyl Ester Structure and Properties: Similar reactivity to vinyl acetate producing random copolymers ■ ■ Easily copolymerisable with ethylene, acrylates and methacrylates Versatic Acid 9 and 10 Structure and Properties: Hydrophobic ■ ■ UV resistant ■ Hydrolytically stable ■ Non-hazardous Protection of vinyl acetate against hydrolysis by adjacent VeoVa monomer groups H2O OH H2O OH H2O H2O H2O OH OH O O O O O O O O O O O O Polymer chain Protected vinyl acetate The various VeoVa monomers mainly differ in the degree of branching and the length of the hydrocarbon groups. This leads to differences in the glass transition temperature of their homopolymers, and consequently to a different behaviour as modifying comonomers. Whereas VeoVa 9 monomer provides rigidity to the copolymer, VeoVa 10 monomer is known as a flexibilising comonomer. Reactivity of VeoVa monomers VeoVa monomers can be used with a variety of other monomer types to produce copolymers. The ease of polymerisation depends on the reactivity ratios of VeoVa monomer Tg of homopolymers Monomer Tg [ °C ] VeoVa 9 + 70 VeoVa 10 -3 the monomers used. VeoVa monomers copolymerise very easily with other vinyl esters, ethylene and most acrylic monomers. Reactivity ratios of vinyl ester monomers with other monomer types Monomer 2 Temp. [ °C ] r1 r2 Source Styrene VeoVa 10 VeoVa 10 140 170 25 23 0.04 0.06 2 2 2-Ethylhexylmethacrylate VeoVa 10 VeoVa 10 140 170 10.5 3.6 0.08 0.06 2 2 Monomer 1 Methyl Methacrylate Vinyl Acetate 60 20 0.015 1 Ethyl Acrylate VeoVa 9 60 6 0.10 2 Butyl Acrylate Vinyl Acetate - 5.89 0.05 1 Vinyl Acetate VeoVa 10 VeoVa 9 Ethylene 60 60 130 0.99 0.93 1.02 0.92 0.90 0.97 1 1 1 1 Young, Polymer handbook, Chapter II, J. Brandrub, E.H. Immergut and W. McDowell, Eds., Wiley-Interscience, New York, 1975 2 Laboratory measurements Reactivity of VeoVa monomers with vinyl acetate VeoVa monomers are commonly used as comonomers for vinyl acetate in emulsion polymerisation because they exhibit a similar reactivity. During emulsion or solution polymerisation, VeoVa monomer and vinyl acetate are converted at the same rate. They can be copolymerised in any desired ratio, producing polymers with a random microstructure. This allows the key performance characteristics of VeoVa monomers to be fully exploited. Commonly used emulsion polymerisation temperatures are in the range of 76 – 80 °C, with potassium persulphate as initiator. Vinyl acetate and VeoVa 10 instantaneous monomer conversion determined by Gas Chromatography during a semi-continuous emulsion polymerisation process Instantaneous conversion [ % ] 100 80 60 Start monomer addition End monomer addition Post cooling allows reducing the residual monomer content down to < 100 ppm levels 40 20 0 50 100 150 200 250 300 350 400 Time [ min ] VeoVa 10 Vinyl acetate Reactivity of VeoVa monomers with (meth)acrylates VeoVa monomers can be polymerised with acrylate and methacrylate monomers in emulsion, in solution or in bulk. Optimum results are generally obtained by using a semi-continuous process. This results in better control of the reactor temperature and in polymers with a more random microstructure. For emulsion polymerisation, a slightly higher reaction temperature of 85 °C is recommended to achieve a more random polymer structure. For solution or bulk polymerisation, the best results are obtained at 140 °C and above. Reactivity of VeoVa monomers with styrene VeoVa monomers do not polymerise with styrene in emulsions. Higher temperatures are required to achieve good control over the reaction, and acrylate monomers should be present to bridge the reactivity differences. Suitable recipes for solution and mass polymerisation at temperatures around 160 °C are described in separate bulletins. Handling precautions For more detailed information on all aspects of Health, Safety and Handling, please reference the Safety Data Sheets of VeoVa monomers, which are available from your local Momentive representative or distributor. The precautions advised therein should be strictly observed. For details related to other products listed in this bulletin, please contact the suppliers of those products. Momentive: The Science Behind What Lies Ahead At Momentive, our global team is focused on delivering value by helping our customers make their products and processes better. 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