Synthesis of novel well-defined chain-end- and in-chain-functionalized polystyrenes with one, two, three, and four perfluorooctyl groups and their surface characterization

Various chain-end and in-chain functionalized polystyrenes with one, two, three, and four perfluorooctyl (C8F17) groups with well-defined structures (M-n = (3.5-29) x 10(3) g/mol) were synthesized by the addition reaction of polystyryllithiums to phenol-functionalized agents such as 1-(4-bromobutyl)-4-tert-butyldimethylsilyloxybenzene, 1-(4-tert-butyldimethylsilyloxyphenyl)-1-phenylethylene, and 1,1-bis(4-tert-butyldimethylsilyloxyphenyl)ethylene and the subsequent Williamson reaction with C8F17(CH2)(3)-Br to introduce C8F17 groups via the phenol functions regenerated after deprotection. In addition, chain-end-functionalized polystyrene with C8F17 group at both ends and in-chain-functionalized polystyrenes with one and two C8F17 groups introduced at two positions in chains were synthesized in a similar fashion using difunctional living polystyrenes. Surface structures of annealed films prepared from such C(8)F(17)chain-functionalized polystyrenes were characterized by angle-dependent XPS and contact angle measurements using water and dodecane droplets. Both measurements confirmed that the C8F17 group segregated and preferentially enriched at the surfaces in virtually all films. The degree of surface enrichment increased with the number of C8F17 groups and, on the other hand, decreased with the molecular weight of the functionalized polymer. The terminal C8F17 group was usually much more effective for surface enrichment than the internal group in the same number. On the assumption that this moiety is highly ordered and oriented with the chain axis perpendicular to the surface, it can be speculated from the F/C values at 10degrees TOA by XPS in some polymers that all surface areas of these films are completely covered with the C8F17C3H6OC6H4 moiety.