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[(BA-C8) 18 –(6FBA)] n was synthesized by condensation polymerization of poly(bisphenol A- co -octane) containing 18 repeat units with bromine end groups, (Br–(BA-C8) 18 –Br), and 4,4′-(hexafluoroisopropylidene)diphenol (6FBA). This copolymer was confirmed to be semicrystalline after a single melting temperature was detected by differential scanning calorimetry. The changes in the surface chemical composition were measured using time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy, the changes in the surface energy were measured using contact angle measurements, and the changes in the surface morphology were detected using atomic force microscopy as the copolymer crystallized. A decrease in the surface fluorine concentration with time was detected because of the movement of the low surface energy units (6FBA) to the bulk during the development of the crystalline phase. This result shows that the decrease in the enthalpy as a result of crystallization overcomes the increase in the surface free energy due to the migration of the low surface energy units to the bulk and the decrease in entropy due to demixing.

The polymers BA-C8 and 6FBA-C8 were obtained by condensation polymerization of 1,8-dibromo-octane with bisphenol A and 4,4′-(hexafluoroisopropylidene)diphenol, respectively. A blend (BA-C8/6FBA-C8 (80/20)) containing 80 wt% of BA-C8 and 20 wt% 6FBA-C8 was prepared. Only one glass transition temperature was detected using a differential scanning calorimeter, suggesting that the blend is miscible. The surface chemical and morphological properties of the blend were studied as BA-C8 crystallized using atomic force microscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and contact angle measurements. The results of the surface analyses showed that the surface of the blend was found to be enriched in the 6FBA-C8 polymer, especially at the crystalline regions. The crystalline regions were found to be raised above the amorphous regions. Surface segregation and crystallization were the two main factors that contributed to the changes in the chemical composition and morphology of the surface.