Surface modification of poly(tetrafluoroethylene-co-hexafluoropropylene) ; Surface initiated graft polymerization ; Surface chemistry of fibrillar carbon/ (2021)

Part I of this dissertation deals with the surface modification of poly (tetraf luoroethylene-co-hexaf luoro- propylene) (FEP) .The reduction of FEP using sodium naphtha- lide was studied with regard to the kinetics of reaction and the product structure.The thickness of the resulting modified surface layer could be controlled, using reaction time and temperature, in the ranges of 45-90 and 250-800 A. The air-sensitive reduction product contained carbon-carbon double and triple bonds, aliphatic C-H bonds, alcohols, carbonyls and very little fluorine.Hydroboration/oxidation introduced hydroxyl groups in high yield to the surface.The alcohols exhibited low reactivity in esterif ication reactions in the absence acylation catalysts.Treatment of this surface with ethylene oxide in the presence of LDA ren- dered a more reactive, primary alcohol-containing, surface.Reaction of the hydroxyl surface produced by hydroboration and oxidation with 1,4-toluene diisocyanate or isophorone diisocyanate resulted in surface-bound isocyanate groups.The reactivity of these surfaces towards nucleophilcs was investigated.Part II deals with graft polymerization from surface- confined initiator species.Halogenated surfaces were prepared by treating reduced FEP with chlorine or bromine.Treatment of these surfaces with silver trif luoromethane- sulfonate in the presence of tetrahydrofuran (THF) resulted in the polymerization of THF from the surface.Initiation at temperatures less than -10C, followed by polymerization at -10C, resulted in a relatively thick, homogeneous over- layer of the graft polymer.Neopentyl and n-propyl alcohol groups were introduced to the surface of poly (chlorotri- fluoroethylene) (PCTFE) by reaction with the appropriate protected alcohol-containing lithium reagent.The corre- sponding tosylate surfaces were prepared and the reaction of these surfaces with 2-methyloxazoline was studied.Acryl- amide monomers were polymerized from hydroxyl surfaces derived from FEP using eerie ion redox initiation.The introduction of trimethylsilyl ketene acetal groups to polymer surfaces was also investigated.vi LIST OF TABLES Table Page 1 XPS atomic composition data for labeling of FEP-C 63 2 XPS atomic composition data for acylation of FEP-OH with heptaf luorobutyryl chloride 81 3 XPS atomic composition data for primary hydroxyl surfaces derived from ethylene oxide 86 4 XPS atomic composition data for other primary hydroxyl surfaces90 5 XPS atomic composition data for reactions of PCTFE-diMe-OH surfaces with TfCl and Tf20. . .220 16 XPS atomic composition data for tosylate surfaces 222 17 XPS atomic composition data for 2-methyloxazoline graft polymerizations 225 18 XPS atomic composition data for reactions of isobutyrate surfaces 232 19 XPS atomic composition data for phenylethyl ester surfaces 240 XPS atomic composition data for reactions of phenylethyl ester surfaces 242 XPS atomic composition data for attempted surface-initiated GTP polymerizations 244 XPS atomic composition data for reactions with LiPrTMSKA 247 XPS atomic composition data for reactions of isocyanate surfaces with e-caprolactam 253 XPS atomic composition data for fibril oxidations 304 2 5 XPS atomic composition data for reduced fibrils 308 26 XPS atomic composition data for Tl-labeled fibrils 312 27 XPS atomic composition data for reactions of Tl-labeled surfaces with HFBC 314 28 XPS atomic composition data for BF,* OEtj catalyzed reactions of fibril samples with CF3CHN2 29 XPS atomic composition data for hydrolysis (IN HCl) of CF3CHN2 labeled fibrils 318 30 XPS atomic composition data for HFBC labeled fibrils 31 XPS atomic composition data for DNPH labeled fibrils ^20 xvii 32 XPS atomic composition data for reactions of fibrils using CDI and DCC 3 3 XPS atomic composition data for DBU catalyzed reactions of fibrils with electrophiles 34 Results of titration #1 35 Results of titration #2 36 Summary of titration results 37 Summary of chemical composition estimates based on fibril reactivity 38 XPS atomic composition data for reactions with CF3CHN2 in the presence of CuACj- 39 XPS atomic composition data for reaction with ethyl diazoacetate xviii LIST OF FIGURES Figure Page 1 Schlenk tube 20 2 Trap-to-trap apparatus 20 3 UV-visible spectrum of FEP-C (4 h, 0C) 54 4 Reaction depth versus reaction time for sodium naphthalide reduction of FEP at 0C (, ) and -78C () 56 5 XPS spectra (C^g region) of FEP, FEP-C (-78C, 4 h) and FEP-C (0C, 4 h) recorded at 15a nd 75t akeoff angles 58 6 ATR-IR spectra of (a) FEP, (b) FEP-C, H2O/THF, (c) FEP-C, THF/H2O/THF, (d) FEP-C, fully deuterated 61 7Reaction depth versus reaction time for sodium naphthalide reduction of PTFE at 0C (!) and -78C () 70 8 XPS spectra (C^^region) of sodium naphthalide-reduced PTFE (-78C, 4 h) recorded at 15( a) and 75( b) takeoff angles 71 9 Reaction depth versus time for benzoin dianion reduction of FEP at 50C (,*), FEP at 21C (a) and PTFE at 50C () 73 10 XPS spectra (C^g region) of benzoin dianion- reduced FEP (50C, 4 h) recorded at 15( a) and 75( b) takeoff angles 76 11 ATR-IR spectra of (a) FEP-OH; (b) FEP-OH reacted with HFBC, THF/pyridine; (c) FEP-OH reacted with HFBC, pyridine/DMAP 78 12 XPS spectra (C,.region) of (a) FEP-OH (b) FEP-OH reacted with HFBC, THF/pyridine (c) FEP-OH reacted with HFBC, pyridine/DMAP "^1 3 IR spectrum of (4-dimethylamino) pyridinium heptafluorobutyrate xix 14 ATR-IR spectra of (a) FEP-EO-OH (b) FEP-EO-OH reacted with HFBC (c) FEP-C, reacted with BPO and methanol 87 15 ATR-IR spectra of (a) FEP-9BBN (b) FEP-CHjOH 91 16 ATR-IR spectra of (a) FEP (IPDI ) -NCO and FEP(IPDI)-NCO reacted with (b) BrPrOH (c) BrPhEtOH (d) BrPhEtOH and MeOH 98 17 ATR-IR spectra of (a) PCTFE (IPDI) -NCO and PCTFE( IPDI) -NCO reacted with (b) BrPrOH (c) MeOH 100 18 ATR-IR spectra of (a) FEP(TDI)-NCO and FEP(TDI)-NCO reacted with (b) BrPrOH (c) BrPhEtOH (d) BrPhEtOH and MeOH 103 19 ATR-IR spectra of (a) PCTFE (TDI) -NCO and PCTFE (TDI) -NCO reacted with (b) BrPrOH (c) MeOH 104 ATR-IR spectra of (a) FEP-OH; (b) FEP-g-pAA, high [Ce*^]; (c) FEP-g-pAA, low [Ce'^] ; (d) FEP-g-pAA, high [Ce'^], extracted 171 SEM micrograph of FEP-g-pdMAA 175ATR-IR spectra of (a) PCTFE-OH; (b) PCTFE-OH + TPP-Al-Cl/P.0188 ATR-IR spectra of (a) FEP-Cl ; (b) FEP(Cl) -g-THF, reacted at room temperature.. 192 ATR-IR spectra of (a) FEP (CI) -g-THF, reacted at room temperature; FEP (Br) -g-THF reacted at: (b) -78C/-10C, (c) -23C/-10C, (d) -10C; (e) FEP (CI) -g-THF, reacted at -23C/-10C 199 25 XPS spectra (C^g region) of (a) FEP-Br; (b) FEP(Br) -g-THF, -78C/-10C; (c) FEP (Br) -g-THF, -78C/-10C, ^He* ion etched 202 26Curve fitting results (XPS, C,s region) for FEP (Br) -g-THF, -78C/-10C 203 27 'He* ion etching results for FEP (Br) -g-THF, reacted at -78C/-10C 204 XX 28 ATR-IR spectra of (a) PCTFE-OH, (b) PCTFE-OH + TfCl in pyridine 211 29 ATR-IR spectra of PCTFE-diMe-OH prepared by reaction for (a) 5.5 h at 0C in 0.7:1 THF/hept.;(b) 6.5 h at -30C in 1.7:1 Et^O/ hept.; (c) 4 h at -20C in 5:1 THF/hept 215 30 ATR-IR spectra of (a) PCTFE-OH; (b) PCTFE-OTos, #4; (c) PCTFE-g-2M0, #1; (d) PCTFE-g-2Mo, #4; (e) PCTFE control 224 31 ATR-IR spectra of (a) PCTFE-OC (=0) iBu PCTFE-OC(=0) iBu reacted with (b) LDA/TMSCl, (C) TEA/TMSCl, (d) TEA/TMSOTf 231 32 ATR-IR spectra of (a) PCTFE-OC (=0) CH2Ph, (b) PCTFE-OC (=0) CH2Ph + TEA/TMSOTf 238 3 3 ATR-IR spectra of PCTFE-diMe-OC (=0) CH2Ph prepared in (a) pyridine, (b) THF/pyridine/DMAP; (c) reaction of product (b) with TMSOTf/TEA in benzene, (d) reaction of product (b) with TMSOTf/TEA in TCE 241 34 ATR-IR spectrum of PCTFE reacted with LiPrTMSKA 248 3 5ATR-IR spectra of (a) FEP-CL, prepared in THE, (b) FEP-g-CL prepared in THF, (c) FEP-CL prepared in the melt, (d) FEP-g-CL prepared in the melt 2 54TEM micrograph of graphite fibrils 272 Schlenk-type filter apparatus 284 XPS spectra (C^^region) of (a) "as received" and (b) oxidized carbon fibrils... 305 XPS spectra (0^^r egion) of (a) "as received" and (b) oxidized carbon fibrils... 306 XPS spectra of "as received" fibrils reacted with CF3CHN2 in the presence of CUAC2-H20 ^-^X X i LIST OF EQUATIONS Equation .Page 1 Reaction of FEP-OH with LDA and ethylene oxide 84 2 Ceric ion initiated polymerization of acrylate monomers 168 3 Aluminoporphyrin initiated "immortal" polymerization of epoxide monomers 177 4 Preparation of TPP-Al-Et and reaction of TPP-Al-Et with alcohols 178 5The effect of temperature on the reaction of AgOTf and THE with PSBr 196 6 Effect of ion etching on low temperature- initiated THE graft surfaces 205 7 Elimination of PCTFE-OH in the presence of TfCl and pyridine 209 8 Polymerization of 2-methyloxazoline 221 9 Group transfer polymerization 228 10 Charge delocalization in 1-ethoxy-l- (trimethylsilyloxy) -2-phenyl ethylene 236 11 Preparation of LiPrTMSKA 245 12 Activated monomer polymerization of e-caprolactam 251 13 Half reaction for chlorate oxidation 302 14 Half reaction for perchlorate oxidation 303 15Reaction of graphitic carbon with carbenes..