UNSATURATED POLYESTER RESINS MODIFIED WITH PERFLUOROPOLYETHERS

Telechelic macromers based on hydroxyterminated perfluoropolyethers (H O-R-H-PFPE-R-H-OH) with different molecular weights were used for the preparation of fluorine-containing unsaturated polyester resins (FUPR) . The products resulting from the reaction of the monomers usually emp loyed for the preparation of unsaturated polyesters with HO-R-H-PFPE-R -H-OH were in any case milky liquids. The degree of reaction of the hy droxyl terminal groups of HO-R-H-PFPE-R-H-OH was monitored by H-1-NMR analysis on the fractions collected after sedimentation experiments; a mount and composition of the sediment and sedimentation rate were foun d dependent on both the molecular weight of fluorinated macromer and t he method used for polyesterification. The molecular weight of HO-R-H- PFPE-R-H-OH and the reaction conditions had also a strong influence on the final morphology of crosslinked polymers. A very poor interphase adhesion was observed when unreacted HO-R-H-PFPE-R-H-OH was blended wi th the unsaturated polyester. On the contrary, when the fluorinated ma cromer was allowed to react during polyesterification, the adhesion of the fluorine-rich dispersed phase to the unsaturated polyester matrix was good for low molecular weight HO-R-H-PFPE-R-H-OH and when the flu orinated prepolymer had been modified by a previous reaction with chlo rendic anhydride, but it was poor, as for unreacted macromers, for hig h molecular weight HO-R-H-PFPE-R-H-OHs. FUPRs prepared using a low mol ecular weight HO-R-H-PFPE-R-H-OH exhibited a significant improvement o f the flexural strength even at very low level of addition (3% by wt). (C) 1998 John Wiley & Sons, Inc.