Styrene, copolymerization with soybean oils

Considerable recent effort has been directed towards the conversion of vegetable oils into solid polymeric materials. These vegetable oil-based polymers generally possess viable mechanical properties and thus show promise as structural materials in a variety of applications. For example. Wool and coworkers have prepared rigid thermosets and composites via free-radical copolymerization of soybean oil monoglyceride maleates and styrene (10-12). The new maleate monomers are obtained by glycerol transesterification of soybean oil, followed by esterification with maleic anhydride (10). It has been... 

Knot et al. (51) converted soybean oil to several monomers for use in structural applications. They prepared rigid thermosetting resins by using free radical copolymerization of maleates with styrene. The maleates are obtained by glycerol trans-esterification of the soybean oil, followed by esterification with maleric anhydride. They also synthesized several TAG-based polymers and composites and compared their properties. It was found that the moduli and glass transition temperature (Tg) of the polymers varied and depended on the particular monomer and the resin composition. They proposed that the transition from glassy to rubbery behavior was extremely broad for these polymers as a result of the TAG molecules acting both as cross-linkers as well as plasticizers in the system. 

The double bonds in soybean oil can be converted to reactive monomers (Khot et al., 2001 Wool et al., 2002a,b). These reactive monomers (maleates) are copolymerized with styrene through free radical mechanism to form rigid thermosetting resins. The maleates are obtained by glycerol transesterification of soybean oil followed by esterification with maleic anhydride. Several triacylglycerol-based polymers and composites were synthesized, and their properties compared. 

In the same fashion, methacrylate groups have also been incorporated in soybean oils to generate similar polymer architectures. Acrylated epoxidized soybean oil and maleinated acrylated epoxidized soybean oil were reacted with methacrylated lauric acid as a method of reducing styrene input [41]. This increased both the visocosity and the glass transition temperature when compared with the styrene analogue as well as having the benefits of improving the environmental properties of the polymer even further. Acrylated, epoxidized soybean oil was copolymerized with methyl methacrylate in a polymerization initiated by benzoyl peroxide to produce a clear bioplastic [42]. 

These foams can then be extended into the area of flame-retardant materials, where methyl oleate-polyesters were used as polyols in the synthesis of silicon-containing polyurethanes [89]. Despite not strictly being foams, methyl oleate, soybean and sunflower oils have also been investigated to produce semi-rigid flame retardant materials [90]. In this instance, they were brominated, acrylated and then radically copolymerized with styrene to form the polymeric material. 

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