Fluorinated polyhedral oligomeric silsesquioxane-based shape amphiphiles: molecular design, topological variation, and facile synthesis

This paper reports the design and synthesis of fluoroalkyl-functionalized polyhedral oligomeric silsesquioxane (FPOSS)-based shape amphiphiles with two distinct topologies: (i) mono-tethered FPOSS-poly(epsilon-caprolactone) (PCL) and (ii) FPOSS tethered with two polymer chains possessing different compositions, namely, polystyrene (PS) and PCL, denoted as PS-(FPOSS)-PCL. The synthetic strategy features an efficient "growing-from" and "click-functionalization" approach. From a monohydroxyl-functionalized heptavinyl POSS, a PCL chain was grown via ring opening polymerization (ROP) of epsilon-caprolactone; subsequent thiol-ene "click" chemistry with 1H, 1H, 2H, 2H-perfluoro-1-decanethiol allowed the facile introduction of seven perfluorinated alkyl chains onto the POSS head. Similarly, PS-(FPOSS)-PCL was synthesized from a PS precursor bearing both hydroxyl group and heptavinyl POSS at the omega-end, which was prepared by living anionic polymerization and hydrosilylation. The compounds were fully characterized by H-1 NMR, C-13 NMR, FT-IR spectroscopy, MALDI-TOF mass spectrometry, and size exclusion chromatography. The introduction of perfluorinated molecular cluster into polymers is expected to make them surface-active while the interplay between crystallization and fluorophobic/fluorophilic bulk phase separation in these shape amphiphiles shall lead to intriguing self-assembly behavior and novel hierarchical structures. This study has demonstrated FPOSS as a versatile building block in the construction of shape amphiphiles and established a general and efficient method to introduce such fluorous molecular clusters into polymers.