Improving Maleimide Properties: A Fluorinated Copolymer Approach for Thermal Stability and Water Repellency

A novel perfluorinated maleimide monomer, 3,5-bis((perfluorophenyl)methoxy)benzyl-4-(2,5-dioxo-2,5-dihydro-1 H-pyrrol-1-yl)benzoate (FMI), containing a perfluorinated aromatic group was synthesized using N-[4-(chlorocarbonyl)phenyl]maleimide, 3,5-bis(perfluorobenzyl)oxybenzyl alcohol, and triethylamine. Free radical polymerization of FMI monomer and its copolymerization with styrene (St) were performed at 75°C in the presence of 2,2′-azobisisobutyronitrile as an initiator in toluene for styrene containing copolymers. The obtained copolymers were characterized by ¹H-NMR spectroscopy and gel permeation chromatography (GPC). The thermal properties were examined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods. The maleimide structure prevented molecular movement of the main chain and increased the glass transition temperature. The FMI monomer in the copolymers significantly increased the thermal stability, especially at half a percent degradation and residue amount in TGA analyses. The topography of the polymers containing the FMI monomer was evaluated using scanning electron microscopy (SEM) to examine the effect of fluorine on the structure. To investigate the wetting behavior of these polymers, thin films were prepared using the spin-coating method, and the surface contact angle values were measured with distilled water and ethylene glycol. Contact angle measurements of thin films coated by the spin-coating method showed that the surface wettability of the films decreased significantly with increasing polymer FMI ratio.