Bis-perfluorocycloalkenyl (PFCA) aryl ether monomers towards a versatile class of semi-fluorinated aryl ether polymers

Soluble, microporous ladder polymers formed by stepwise nucleophilic substitution of octafluorocyclopentene

“…The molecular weight decreased with increasing temperature (Table 1, LIN P4 vs. P5/P6) probably because of side reactions like allylic substitution as well as transetherification. The molecular weight of the linear polymer LIN P3 is comparable to similar polymers reported previously 6,7 and obtained by using triethylamine as the base. Further increase in temperature led to the formation of lower molecular weight polymers.…”

Triarylamine-enchained semifluorinated perfluorocycloalkenyl (PFCA) aryl ether polymers

“…1). As expected, PFCA Scheme 3 Nucleophilic attack on PFCA rings leads to vinyl and allyl products [28] aryl ether monomers derived from OFCP, there was no product with allyl substituted enchainments [31].…”

“…However, as the literature demonstrates, the ratio of vinyl to allyl substituted products varies and depends on the PFCA ring size, nucleophilicity of attacking anion, and reaction conditions. [28,31,32].…”

AB-type monomers for the preparation of perfluorocycloalkene (PFCA) aryl ether polymers

“…The angle strain of fluoro-olefins are typically relieved upon fluoride substitution accompanied by an increase in stabilizing s-character. Crystal structures of PFCAphenol compounds and precursors have not been solved, but the AA-type of PFCA monomers shown in Scheme 2 (bottom) have been previously reported [28]. From these crystal structures we can see that upon mono-substitution of PFCP with one equivalent of phenoxide the remaining C olefin -F bond extends to 1.338 Å with no change in nR-C olefin -F. The longer C olefin -F bond is attributed to substitution of the first C olefin -F with an electron-donating ether bond (C olefin -O-Ar) alpha to the remaining C olefin -F. The lack of angle strain relief after the first substitution suggests that the remaining C olefin -F is highly electrophilic.…”

“…The PFCP-derived AA-type monomer was reported to produce a similar degree of polymerization as the first method that used PFCP directly [25]. A recent report [28] that included 19 F NMR spectra and gas chromatograms for the monomers prepared via the route shown in Scheme 2 (bottom) suggested that allylic substitution may be occurring, but was not quantified nor were the consequences of allylic substitution on polymerization discussed. The synthetic protocol developed and described herein provides an opportunity to quantify the vinylic and allylic substitution of PFCA compounds with phenoxides.…”