Pentafluorostyrene: A valuable and flexible material design tool when mastered by ATRP

Pentafluorostyrene is an intriguing monomer and has turned out to be an indispensable tool in the architecture of various functional materials. The ATRP merits with pentafluorostyrene was revealed a decade ago and since then especially the lability of the para-fluorine of pentafluorostyrene has been exploited by the nucleophilic substitution methodology to create numerous other monomers. Two very recent applications have exploited short alkyne initiated poly(pentafluorostyrene)s. The first example is development of polyelectrolyte materials comparable to the industrial fuel cells standard Nafion®. Our solution to this polyelectrolyte challenge is the combination of a thermally and chemically very stable backbone PSU (M_n ∼40,000 Da), which is also an excellent film forming material, with poly(pentafluorostyrene) grafts that additionally ensures high thermal stability as a very promising scaffold for phophonates for polymer electrolyte membranes. This design idea was executed by use of CuAAC, where clickable azides were fabricated on the PSU (7 mol%) through lithiation chemistry at low temperature introducing first chloromethyl followed by conventional conversion of chloro groups to azides by sodium azide treatment. After clicking the two components together the poly(pentafluorostyrene) grafts were phosphonated. Graft copolymer (PSU-g-PhPFS) membranes could be cast that showed high thermal stability and proton conductivity. Soft silicone elastomers are materials in demand for actuators or energy production e.g. through wave harvesting. Functionality can be introduced to the commercially available silicone formulations by use of functional cross-linkers. In this particular case a short PFS-A was “clicked” to the cross-linker. A poly(pentafluorostyrene) enrichment of the surface of the cured silicone elastomer was observed by a water contact angle (WCA) of 116o as opposed to a plane silicone elastomer with a WCA of 108^o. This is in contrast to other applied functionalities that was shown by confocal microscopy to be evenly distributed throughout the elastomer matrix.