Precise synthesis of novel chain-end-functionalized polystyrenes with a definite number of perfluorooctyl groups and their surface characterization

We have successfully synthesized two types of chain-end-functionalized polystyrenes with a definite number of C8F17 groups that are dendritically distributed and linearly aligned in a double line. They are referred to as D and L types, respectively. In each type, there are three series of polymers whose C8F17 groups are connected to the main polystyrene chains by pheryl ether, benzyl ether, and benzyl ester linkages. A definite number of C8F17 groups from 2 to 32 and 1 to 10 are introduced at the chain ends of D and L type polymers, respectively. The resulting polymers all were well-defined in architecture and precisely controlled in chain length and degree of chain-end functionalization of C8F17 group. These polymers were cast into film and, after annealing, examined the surface segregation behavior Of C8F17 group by angle-dependent X-ray photoelectron spectroscopy and contact angle measurements using water and dodecane droplets. All of the C8F17-chain-end-functionalized polymers showed fairly large surface segregation and enrichment of C8F17 group- Furthermore, it was found that the segregation behavior strongly depended on the number and the alignment of C8F17 group and the linkage between C8F17 group and main chain. In general, the extent of the enrichment increased with increasing number of C8F17 groups and appeared to be saturated at a certain number Of C8F17 groups, ranging from 4 to 16 depending on the polymer series.