Near-surface crystallization of PET

Crystallization of polymer chains confined in nanodomains

“…In fact, it is found from many studies on the crystallization behavior that the crystallinity of block chains confined in nanolamellae increases sigmoidally with a finite induction time, indicating that the crystallization is virtually driven by a combined mechanism of heterogeneous nucleation and subsequent crystal growth. Because a comprehensive understanding of the detailed crystallization mechanism of homopolymers confined in nanolamellae is directly applicable to the surface crystallization of homopolymers [88][89][90][91][92] or crystallization within thin films [93][94][95][96][97][98], it is essential to examine the crystallization of homopolymers (and also block chains) confined in various nanolamellae.…”

Application of helium ion microscopy to nanostructured polymer materials

“…In our study, ultrathin PET and PEN films were prepared from polymer solutions via spin-or dipcoating procedures, which suppressed the crystallization process during polymer film fabrication. Subsequent in situ annealing of the samples at various temperatures allowed monitoring of the diffusion-limited cold crystallization process by AFM [93].…”

“…Formation of surface crystals with a special dendritic morphology is observed for ultrathin films with the thickness comparable with the radius of gyration of polymer chains. Based on our AFM studies, a phase diagram of diffusion-limited crystallization behavior (in temperature-film thickness coordinates) was constructed [93]. Existence of three characteristic layers (as shown in Figure 7A) determines the features of crystallization behavior in thin films of crystallizable polymers [13,93].…”

“…Based on our AFM studies, a phase diagram of diffusion-limited crystallization behavior (in temperature-film thickness coordinates) was constructed [93]. Existence of three characteristic layers (as shown in Figure 7A) determines the features of crystallization behavior in thin films of crystallizable polymers [13,93]. Figure 7 shows typical surface crystal morphology as observed by AFM in comparison with HIM imaging.…”

Phase Separation and Crystallization in High Hard Block Content Polyurethane Thin Films

“…In addition, the increased mobility of chains near the free surface gives rise to a lower surface glass transition temperature (T g ), and polymer surface crystallization, for example, has been shown to occur at a temperature much lower than the bulk crystallization temperature (T c ) due to the lower T g in the surface region. 20 Hsu and co-workers 21,22 reported that the phase separation of TPUs in thin films would be restricted when the films thickness is below 200 nm, and this effect becomes more obvious when the thickness is around 100 nm. Later work by Kojio et al 23 suggested that below a certain film thickness the crystallization of HS is confined, leading to a depression in phase-separated domain size.…”