Onset of surface segregation controlled by the segment length of the low-energy component of polymers

Films of a series of polymers with variable CF2 segments were studied by angle-dependent X-ray photoelectron spectroscopy (ADXPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). The effects of the length of the CF2 segment on the surface composition of the polymers were investigated. ADXPS results indicated that the CF2 segment segregated on the surface of the polymers after thermal annealing at temperatures above their bulk glass transition temperatures when the number of CF2 units was increased to 8. Because of the higher surface sensitivity, ToF-SIMS results showed more CF2 segments at the topmost surface than shown by ADXPS.