The preparation and characterization of highly fluorinated poly(arylene alkylene ether)s

A series of highly fluorinated poly(arylene alkylene ether)s, P6C(F)Xs (X = Non, S, K, SO, Ox) have been prepared by polycondensation reactions of 1H,1H,6H,6H,-perfluorohexane-1,6-diol (6C(F)-diol) with a series of decafluorodiphenyl compounds (DFPXs) including decafluorobiphenyl (DFP), decafluorodiphenyl sulfide (DFPS), decafluorobenzophenone (DFPK), decafluorodiphenyl sulfone (DFPSO), and decafluorodiphenyl oxadiazole (DFPOx). This aromatic nucleophilic substitution polycondensation can be effectively activated by cesium fluoride (CsF) and was completed in a few hours in N,N-dimethylacetamide (DMAc) at room temperature. High molecular weight polymers (M-n = 28 200-64 200 Da) have been prepared from DFP, DFPS, DFPSO, and DFPOx, while the reaction from DFPK only yields low-molecular weight materials (M-n < 8 000 Da). A model reaction using excess 6C(F)-diol (2.5 equiv of DFPK) reveals that the ketone linkage of the DFPK unit is cleaved by the attack of the activated hydroxyl group in the diol during the polycondensation. This cleavage is suppressed when potassium fluoride (KF) was used as a base, and a high molecular weight P6C(F)K (M-n = 33 200 Da) has been prepared. DSC analysis shows that all the resultant polymers are semicrystalline materials, and the melted samples display different crystallization rates in the order of P6C(F)Non > P6C(F)Ox > P6C(F)K > P6C(F)SO similar to P6C(F)S. This sequence is correlated with the bond angles of the X linkages, suggesting a significant influence of the bending of the X linkages on the crystallization capability of the polymers. The P6C(F)Non film has a hydrophobic surface with a water contact angle of 110 degrees, while the other polymers showed reduced values with the increase of the polarities of the X linkages in the order of P6C(F)Non > P6C(F)S > P6C(F)K > P6C(F)Ox > P6C(F)SO.