| Abstract
| - Poly(styrene-b-semifluorinated isoprene) block copolymers with −CF2H-terminated sidegroups were synthesized by the esterification reaction of a poly(styrene-b-hydroxylated 1,2-/3,4-isoprene)block copolymer with semifluorinated acid chlorides. Two distinct first-order transitions were observedby DSC measurements in the resulting block copolymers at temperatures below the glass transition ofpolystyrene. The transition temperatures of the longer fluorocarbon units (10 −CF2− units) were foundto be higher than the shorter fluorocarbon units (eight −CF2− units). By comparing the block copolymershaving −CF3 end groups with those with −CF2H end groups, it was found that both the thermal behaviorand surface properties are significantly affected by the terminal group of the semifluorinated side chainsin the block copolymer. NEXAFS spectroscopy reveals that, although the surface coverage by semifluorinated groups is roughly the same regardless of whether the ends are −CF2H or −CF3, the orientationalorder of the −CF2H surfaces is significantly poorer than that of the −CF3 surfaces. After long-term waterexposure the −CF2H surfaces were observed to reconstruct to more hydrophilic ones even though theanalogous polymers with −CF3-terminated semifluorinated side chains were quite stable. The ease ofsurface reconstruction is probably related to the relatively poor orientation order of the polymers with−CF2H end groups as determined by NEXAFS.
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