High molecular weight graft stabilisers for dispersion polymerisation of vinylidene fluoride in supercritical carbon dioxide: the effect of architecture

A group of high molecular weight graft stabilisers, both fluorinated and non-fluorinated, were synthesised by thermal ring-opening esterification of anhydride copolymers. These included poly(methyl vinyl ether-alt-maleic anhydride) and poly(maleic anhydride-octadecene) and were reacted with alcohols, including 1H,1H,2H,2H-perfluorooctanol, 1H,1H,2H,2H-perfluoro-dodecanol and 1-octanol. The stabilisers were fully characterised by 1H, 19F and 13C nuclear magnetic resonance, diffuse reflectance Fourier transform infrared spectroscopy, and thermal analysis. Their phase behaviour in supercritical carbon dioxide (scCO2), vinylidene fluoride (VDF), and a mixture of scCO2/VDF was also studied using a variable volume view cell. Each stabiliser was tested for the dispersion polymerisation of VDF in scCO2. The effect of the stabiliser architecture on the molecular weight and morphology of the poly(vinylidene fluoride) (PVDF) polymer product was investigated. Steric stabilisation effects were observed. Gel permeation chromatography and scanning electron microscopy were used for the characterisation of the molecular weight and morphology of PVDF polymers.