Surface studies of polyethers with well-defined segmental length

Two series of polyethers were synthesized by the polymerization of 1, n-dibromoalkane (n = 4, 6, 8, 10, 12, 14 and 18) with bisphenol-A (BA) and 4, 4'-(hexafluoroisopropylidene) diphenol-A. The length of the flexible aliphatic segment changes from 4 Angstrom to 21 Angstrom (corresponding to 4 to 18 CH2 groups). X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and atomic force microscopy (AFM) were used to characterize the surfaces of the polyethers. The influence of the length of the flexible aliphatic segments on the surface composition of the BA and 6FBA polyethers was investigated. The intensity ratios of the characteristic SIMS peaks of the flexible segments to those of the rigid segments were related to the length of the flexible segments and the XPS results confirmed that the SIMS intensity ratios can be used to determine the surface compositions. AFM was utilized to investigate the crystallization process of the BA polymer with n = 8. The appearance of nuclei, the generation of primary lamellae and the formation of spherulites were observed dynamically. Nuclei appeared first as 10 nm dots, some disappeared and a few could grow into lamellae. The lamellae that developed from the nuclei bred more lamellae, which in rum induced secondary nucleation and branching of lamellae and finally led to a spherical appearance.