NMR of perfluoropolyether diols and their acetal copolymers

Abstract

A 19F, 'H, and 13C NMR structural study is presented for a selected sample of a perfluoropolyether macrodiol (ZDOL), as well as one of its copolymers with formaldehyde. From their l9F spectra the average composition of perfluorooxymethylene and -0xyethylene units along the chain is clearly evaluated; the end group analysis allows the calculation of the number average molecular weight and functionality of samples of the macrodiol and, to a first approximation, those of the copolymer. The lH and 13C NMR spectra are studied also in order to clarify the nature of the bridging units in the copolymer between perfluoropolyether segments; in particular the absence of oligo(oxymethy1ene) sequences -(OCH&-is verified. A comparison is also made with the spectroscopic data of a corresponding low molecular weight compound, which was prepared by reaction of trifluoroethanol with paraformaldehyde. For that reference compound the heteronuclear shift correlation 2D NMR spectrum is also reported and discussed.

Preparation and Properties of Poly(urethane-urea) Crosslinked Coatings from Perfluorocopolyethers and Polyfunctional Isocyanurates

“…The solution was kept at 90-100 8C under stirring until the urethane formation was complete. The conversion was controlled by 19 F NMR spectroscopy [8] The main characteristics of FR-H and FR-I resins are summarized in Table 2.…”

Equilibrium and non-equilibrium polycondensation process of segmented poly-perfluoro(oxymethylene-ran-oxyethylene)-carbonates

“…It is evident the strong effect of the functionality; the highest molecular weight (M n ¼ 95 000) polycarbonate obtained from ZDOL B after 8 h is still a high-viscosity, colourless liquid perfectly soluble in the solvent mixture used for the GPC analysis. The 19 F NMR analysis [14] shows that residual, low intensity signals of -CF 2 CH 2 OH ends can be detected (p > 0:99). This means that a further optimisation of the polymerisation conditions (time, temperature and pressure) may lead to the formation of really high molecular weight carbonate extended perfluoropolyether copolymers.…”

Novel Glass Fiber‐Reinforced Composites Having a UV and Peroxy Curable Fluoropolymer Matrix

“…One drop of dibutyltin dilaurate (DBTDL) was added. After 60 min the conversion of urethane formation (CF 2 CH 2 OCONHR-) was 100%, as checked by 19 F-NMR end group analysis, [8] monitoring the shift of -CF 2 CH 2 OH signals (À80.5; À82.5 ppm) to -CF 2 CH 2 O-CONHR-(À78.0; À80.0 ppm). At this point two moles of 2-hydroxyethyl methacrylate (HEMA) were added and the reaction was continued for another 4 hours until no more free -NCO groups were detected by IR spectroscopy (absorption at 2 260 cm À1 Some characteristics of RFMA and RFA resins are shown in Table 1.…”

“…-CF 2 CH 2 OCONHR) according to previously reported methods. [8] FT-IR Spectroscopy FT-IR spectroscopy was carried out with a Nicolet 850 spectrometer. Spectra on liquid resins were obtained by smearing one drop of the resin between two KBr disks (16 scans, resolution 4 cm À1 ).…”