MOLECULAR CHARACTERIZATION AND CHAIN FLEXIBILITY OF LINEAR POLYACETALS CONTAINING POLY-PERFLUORO(OXYMETHYLENE-RAN-OXYETHYLENE) MACROMERS

Proper samples of polyacetals containing poly-perfluoro(oxymethylene-r an-oxyethylene) macromers were synthesized by polycondensation of a fl uorinated macrodiol (Fomblin (R)ZDOL) and formaldehyde and fractionate d by solvent/non-solvent separation. Of eight selected fractions, whos e compositional homogeneity was checked by F-19 and C-13 NMR spectrosc opy, the following measurements were performed: M-w by static light sc attering; retention volume V-r at GPC; [eta] by conventional capillary viscometry; glass transition temperature by DSC. 1,1,2-Trichlorotrifl uoroethane was used for solution measurements, from which the second v irial coefficient A(2), the linear M-w-V-r equation of GPC calibration , and the [eta]-M-w Mark-Houwink-Sakurada constants K and a were deter mined. From [eta] and M-w data, the K-theta value (unperturbed state) was estimated by the Stockmayer-Fixman-Burchard extrapolation procedur e, and the characteristic ratio C-infinity of polyacetals containing p oly-perfluoro(oxyethylene-ran-oxymethylene) macromers was calculated t hrough the Fox-Flory equation. Factors related to chain flexibility we re finally discussed and compared with those of corresponding fully pe rfluorinated copolyethers.