Development of chain‐folding of semicrystalline polymers in thin films: a combined ToF‐SIMS and PCA analysis

Poly(bisphenol‐A‐etheralkane), BA‐C n ( n , which is the number of aliphatic CH 2 units, = 8 and 10), composed of rigid and flexible segments, is a semicrystalline polymer. In 50‐nm‐thick films, the polymers tend to develop flat‐on lamellae at the surfaces. Principal component analyses (PCAs) of the ion images were used to discriminate the conformation between the amorphous and flat‐on lamellar surfaces of the polymers. The changes of the surface structure were directly detected by time‐of‐flight secondary ion mass spectrometry chemical imaging when flat‐on lamellae were developed from the polymer melts. These structural changes were related to the lengths of the folded segments, which were strongly influenced by the crystallization temperature. The PCA loading analyses suggested that the length of the folded segments, which contained flexible and the rigid segments with an ether linkage, increased when the crystallization temperature decreased, suggesting the kinetic origin of polymer crystallization.