Synthese und Charakterisierung von Polyvinylphthalatestern als alternative Weichmacher für PVC und andere Polymere
Zusammenfassung der Projektergebnisse
We were able to synthesize 4-vinylphthalic acid esters using a three step synthesis starting with bromination of phthalic anhydride followed by esterification and vinylation using a Suzuki coupling reaction. Bromination of phthalic anhydride led to poor yields between 13 – 24 % which is due to the workup by recrystallization. It was possible to use a crude (not recrystallized) mixture of 4-bromophthalic acid and phthalic acid as the starting material for the esterification. Even though the nonbrominated phthalic esters eluted last, the work-up of the esterification became more time consuming when using non-recrystallized starting material. Yields between 17 % and 94 % were achieved. Vinylation of 4-bromo-phthalic acid esters was done using a Suzuki coupling reaction with previous generation of vinylmagnesiumbromide in situ. Yields ranged from 11 % to 78 %. Overall, no great efforts were made to optimize the monomer synthesis. Polymerization of 4-vinylphthalic acid esters and copolymerization of 4-vinylphthalic acid esters with nbutylacrylate using NMRP was possible. Longer times of polymerizations were needed to achieve high conversions.Still polydispersities are lower than 1.8, which indicates a controlled radical polymerization mechanism. Molecular weights could be adjusted to the desired molecular weight range between Mn = 1000 – 10000 g/mol by varying the amount of initiator. DSC analysis starting at 25°C down to –40°C, followed by heating back up to 75°C did not show any indication of a Tg for any of the samples. The polymers were obtained as viscous, slightly yellow liquids, Tg values apparently below -40 °C, indicating promise as possible plasticizers.
