Molecular weights and molecular dimensions of perfluoropolyether fluids

Abstract

The weight-average molecular weights of a series of fractions from two structurally different types of perfluoropolyether fluids were determined by low-angle laser light scattering. The limiting viscosity numbers of both sets of fractions were measured in Freon W and related to molecular weights. By using established polymer solution theory, the coil dimensions of the molecules were calculated. Samples from both sets of fractions were subjected to analysis by gel permeation chromatography and the coil dimensions were derived by using the principle of universal calibration. Results from both methods agree well. Bulk viscosities and molecular weights were correlated.

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

“…For the sphere and cylinder morphologies, these D values actually correspond to the micelle diameter, and thus factors of $\sqrt{2/3}$ and $\sqrt{3}/2$ , respectively, are required to compare eqs 1–3 with D as listed in Table 1. The value for a PB (6.0 Å) was obtained directly from literature and a PFPO (3.9 Å) was computed from unperturbed chain dimensions reported in the literature 32–34. We neglect the temperature dependence of the statistical segment length, since it is usually weak 35.…”

Fluorinated block copolymers containing poly(vinylidene fluoride) or poly(vinylidene fluoride‐co‐hexafluoropropylene) blocks from perfluoropolyethers: Synthesis and thermal properties

“…Interesting reviews1, 2, 6–9 and articles10–15 supply pertinent information on the syntheses, properties, and applications of these PFPEs.…”

Molecular weight characterization of fluoropolyoxyalkylenes by gel permeation chromatography

“…It is interesting to note that this ratio would be hardly obtainable by direct M , light scattering determination because of the relatively small molecular masses, but also, in our case, because of the particularly low d n / d c value practically realizable with highly fluorinated compounds. 8 From GPC measurements, after calibration, another interesting feature of the fractionation efficiency could be singled out: In spite of the particular fractionation pattern used, the MWD curves of all the fractions showed some "dissymmetry" (as shown in Fig. I), due to a slightly higher proportion of residual low MWs.…”