In order to determine if the alternating tendency of styrene with fluorinated styrenes in free radical copolymerizations correlates with the strength and/or extent of π-π stacking interactions between aromatic fluorocarbons and aromatic hydrocarbons, styrene (St) was copolymerized with 2,3,4,5,6-pentafluorostyrene (PFS) and 4-fluorostyrene (4FS) under a variety of conditions. For the copolymerization of styrene with PFS at 25 °C, r St r FS ) 0.048 and 0.069 in bulk and toluene, respectively, using tert-butylperoxy pivalate as the initiator. For the copolymerization of styrene with PFS at 70 °C using benzoyl peroxide as the initiator, r St r FS ) 0.17 in bulk and r St r FS ) 0.14 in toluene. For the copolymerization of styrene with 4FS, r St r FS ) 0.69 at 25 °C under redox conditions and r St r FS ) 0.62 at 70 °C in bulk. As confirmed by 1 H, 13 C, and 19 F one-dimensional NMR and 1 H-13 C heteronuclear single quantum coherence and 1 H-1 H nuclear Overhauser effect two-dimensional NMR spectroscopy results, St and 4FS tend to form random copolymers whereas the St-PFS copolymers tend to alternate with the alternating tendency increasing with decreasing temperature. The glass-transition temperatures determined by differential scanning calorimetry of the St-PFS copolymers are elevated relative to their mole-average values, whereas those of the corresponding homopolymer blends and the St-4FS copolymers occur at mole-average values. The water and ethylene glycol contact angles of both the St-PFS and St-4FS copolymer films occur at their mole-average values.
2,3,4,5,6-Pentafluorostyrene (PFS) was copolymerized with polybutadiene (PB) in tetrahydrofuran using benzoyl peroxide as the initiator at 50, 60, and 80 8C. The copolymerizations follow typical radical polymerization kinetics and behavior. The grafting parameters were evaluated as a function of monomer conversion, initiator concentration, and/or temperature by gel permeation chromatography of directly injected copolymerization mixtures. The grafting efficiencies and grafting ratios are most consistent with a system that terminates by combination and whose graft sites are generated by hydrogen abstraction of allylic radicals by primary initiator radicals. Pure graft copolymers were isolated by extracting unreacted PB into hexanes and PPFS homopolymer into acetone. The similarity of the glass transition temperatures of the PPFS grafts and the corresponding extracted PPFS homopolymers confirms that their lengths are approximately equal. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2874-2891, 2005
2,3,4,5,6-Pentafluorostyrene (PFS) was copolymerized with b-pinene (PIN) in bulk using benzoyl peroxide as the initiator at 70 8C. The reactivity ratios for PFS (r PFS ) and PIN (r PIN ) were determined by limiting each monomer conversion to approximately 10 mol % or less during 2 h of copolymerization and then plotting the composition data according to both the Fineman-Ross (r 1 ¼ r PFS ¼ 5.2, r 2 ¼ r PIN ¼ 0.070) and Kelen-Tudös (r 1 ¼ r PFS ¼ 5.0, r 2 ¼ r PIN ¼ 0.017) methods. The copolymers exhibited a single glass transition at 60-100 8C, static water contact angles higher than 958, and optical activity with negative specific rotations. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3114-3124, 2006
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