An NMR Relaxation Study of a Hexafluoroisobutylene/Vinylidene Fluoride Copolymer (HFIB/VF₂)

Abstract

Fluorine and proton NMR relaxation data of HFIB/VF2 have revealed an a relaxation associated with the glass transition. This relaxation is characterized by an activation energy of approximately 73 kcal/mol. The transition is observed in both the proton and fluorine data and the proton spin-spin relaxation times can be deconvoluted into crystalline and amorphous components above the glass transition temperature. A local mode relaxation with activation energy of ~9 kcal/mol is observed in the proton data. Reorientation of the CF3 groups is observed in the fluorine data with an activation energy of approximately 5 kcal/mol. What begins as two separate reorientational processes at low temperature probably becomes a complicated reorientational process in the high-temperature limit involving these two processes and the glass transition.

Radical Copolymerization of α,β-Difluoroacrylic Acid with Vinylidene Fluoride.

“…1 H NMR (CDCl 3 ), δ, ppm: 3.5 (s, OH, 1H); 4.1 (ddd, 3 J H(F-2) =15 Hz, 4 J H(F-3) =5.5 Hz, 4 J HH = 1.5 Hz, CH 2 -OH, 2H); 6.4 (dd, 2 J H(F-3) = 49.2 Hz, 3 J H(F-2) = 7.2 Hz, CFClH, 1H). 13 C NMR (CDCl 3 ), δ, ppm: 65.1 (d, 2 J C(F-2) = 24.4 Hz, CH 2 -OH) or 65.2 (d, 2 J C(F-2) =24.4 Hz, CH 2 OH); 97.9 (dd, 1 J C(F-3) = 248.7 Hz, 2 J C(F-2) = 34.3 Hz, CFClH) or 98.3 (dd, 1 J C(F-3) = 251.7 Hz, 2 J C(F-2) =31.0 Hz, CFClH); 110.0 (dd, 1 J C(F-2) =250.9 Hz, 2 J C(F-3) = 25.9 Hz, CFCl) or 110.7 (dd, 1 J C(F-2) = 251.9 Hz, 2 J C(F-3) = 22.4 Hz, CFCl). 19 F NMR (CDCl 3 ), δ, ppm: -130.5 (ddt, 3 J F(F-3) = 19.5 Hz,…”

“…Among these polymers, those containing vinylidene fluoride (VDF) , are of particular importance since they can be thermoplastics, elastomers ,,− or thermoplastic elastomers. ,, They are typically prepared by radical copolymerization of VDF with other fluoroalkenes. Statistic copolymers are usually obtained although few examples of alternating VDF-containing copolymers were reported with hexafluoroisobutylene, − methyl trifluoroacrylate , and α-trifluoromethyl acrylic acid . Many functional fluorinated monomers have been copolymerized with VDF, such as fluoroalkenes or those bearing functional hydroxyl, , acetoxy, carboxy, , thioacetoxy, SF 5 , , or dioxole , groups, and recently summarized …”

“…Diastereoisomer β or R. 1 H NMR (CDCl 3 ), δ, ppm: 3.5 (s, OH, 1H); 4.1 (m, CH 2 -OH, 2H); 6.5 (dd, 2 J H(F-3) = 48.2 Hz, 3 J H(F-2) = 4.0 Hz, CFClH, 1H). 13 C NMR (CDCl 3 ), δ, ppm: 65.2 (dd, 2 J C(F-2) = 24.4 Hz, 3 J C(F-2) = 2.4 Hz, CFClH) or 65.1 (d, 2 J C(F-2) = 24.4 Hz, CH 2 -OH) ; 98.3 (dd, 1 J C(F-3) = 251.7 Hz, 2 J C(F-2) = 31.0 Hz, CFClH) or 97.9 (dd, 1 J C(F-3) = 248.7 Hz, 2 J C(F-2) = 34.3 Hz, CFClH); 110.7 (dd, 1 J C(F-2) =251.9 Hz, 2 J C(F-3) =22.4 Hz, CFCl) or 110.0 (dd, 1 J C(F-2) = 250.9 Hz, 2 J C(F-3) = 25.9 Hz, CFCl). 19 F NMR (CDCl 3 ), δ, ppm: -130.9 (dddd, 3 J F(H 0 -1) = 19.6 Hz, 3 J F(F-2) = 19.6 Hz, 3 J F(H 0 0 -1) = 13.5 Hz, 3 J F(H-3) = 4.1 Hz, CFCl); -148.7 (dd, 2 J F(H-3) =48.2 Hz, 3 J F(F-2) =19.6 Hz, CFClH).…”

“…(CDCl 3 ), δ, ppm: 7.4 (dd, 2 J H(F-3) =69.6 Hz,3 J H(F-2) = 13.8 Hz, HFC, 1H); 9.0 (s, COOH).RMN13 C (CDCl 3 ), δ, ppm: 138.4 (dd, 1 J C(F-2) = 255.4 Hz, 2 J C(F-3) =10.2 Hz, CF); 145.4 (dd, 1 J C(F-3) =280.3 Hz, 2 J C(F-2) = 10.2 Hz, HFC); 158.0 (dd, 2 J C(F-2) = 30 Hz,3 J C(F-3) =9.5 Hz, COOH).RMN19 F (CDCl 3 ), δ, ppm: -139.4 (dd, 3 J F(F-2) = 6.3 Hz, F(H-3) =69.9 Hz, HFC); -152.4 (dd,3 J F(H-3) =13.5 Hz,3 J F(F-3) = 6.7 Hz, CF).Anal. Found: C, 33.27, H, 1.80; F, 35.24.…”

A Spectroscopic Analysis of the Structure of a Hexafluoroisobutylene-Vinylidene Fluoride Copolymer

“…Figure3. Infrared spectra of HFIB/VF2 film; 77 K; 1-cm'1 resolution; (a, top) 3100-2920-cm"1 region; (b, bottom) 1800-400-cm'1 region.…”