Control through monomer placement of surface properties and morphology of fluoromethacrylate copolymers

The arrangement of monomers and morphology of fluorinated copolymers of methyl methacrylate (MMA) were found to be important for controlling the surface energy of the materials when formed into thin films. Novel copolymers of MMA and 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (F3MA) were prepared with different monomer placement, namely statistical and block arrangements of the monomer units. The surface energies decreased with increasing incorporation of F3MA, in a manner consistent with previous reports for similar copolymers; however, the surface energies of the block copolymers were consistently lower than the statistical copolymers. This was interpreted as arising from conformational restriction of presentation of the fluoromonomers to the surface in the statistical copolymers, and formation of phase-separated domains at the surface of the block copolymers. The morphology of the block copolymers was confirmed by small angle X-ray scattering measurements, which allowed calculation of a solubility parameter for the fluorinated segments. The results have implications for the design of more environmentally acceptable materials with ultra-low surface energies