No abstract

The localization of reactive compatibilizers at the interfaces in polymer blends of PLLA (poly(L-lactic acid)) and PVDF (poly(vinylidene fluoride)) was investigated by scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectrometry (EDX) and electron energy loss spectroscopy (EELS). Polyhedral oligomeric silsesquioxane (POSS) functionalized with epoxide groups and poly(methyl methacrylate) (PMMA) chains was applied as compatibilizer in the immiscible PLLA/PVDF (50/ 50 wt %) blend. The blends were successfully compatibilized by adding the functionalized POSS through the chemical reaction of epoxide group with PLLA and the dissolution of PMMA into PVDF phase. The localization behaviors of the POSS compatibilizers at the PLLA/PVDF interfaces, which were influenced by melt-blend conditions, were characterized by EDX elemental analysis. We also investigated the local chemical structures in the interfacial regions by energy-loss near edged fine structure in EELS. We proposed the mechanism of the reactive compatibilization of immiscible polymer blends by the STEM-EDX/EELS analysis of the PLLA/PVDF interfaces compatibilized with the POSS derivatives.

Molar dentine was sliced into 100 nm ultrathin sections, by means of a focused ion beam, for observation by energy‐filtering transmission electron microscopy (EFTEM). Within the matrix, crystals approximately 10 nm wide and 50–100 nm long were clearly observed. When carbon and calcium were mapped in electron spectroscopic images by EFTEM, carbon failed to localize in crystals. However, it was found in other regions, especially those adjacent to crystals. Because carbon localizations were thought to reflect the presence of organic components, carbon concentration in regions near crystals suggested the interaction of crystals and organics, leading to organic control of apatite formation and growth. Ca was present in almost all regions. The majority of Ca localizing in regions other than crystals may be bound to organic substances present in dentine matrix. These substances are thought to both accumulate Ca and act as reservoirs for crystallization of apatite in dentine.

Additional supporting information may be found in the online version of this article.

The distribution of nano‐sized silica in binary rubber blends is characterized by scanning transmission electron microscopy (STEM) tomography combined with energy dispersive X‐ray spectrometry (EDX). 3D distribution of silica is visualized by STEM‐EDX tomography with the tilt‐series of silicon elemental maps, while the phase‐separated morphologies of polyisoprene rubber (IR) and styrene‐butadiene rubber (SBR) are visualized by STEM‐tomography in high‐angle‐annular‐dark field (HAADF) mode. The combination of STEM‐EDX and STEM‐HAADF tomography enables us to determine the distribution of silica between the two rubber phases quantitatively even with high contents of silica up to 70 phr (weight parts per hundred rubber). It is found that silica is preferentially distributed in the SBR phase, but it is also distributed in the IR phase when the IR fraction in the total rubber components is higher than 40 wt%. The preferential distribution of silica in the SBR phase improves the dispersion of the IR domains. This is the first use of this technique for a multicomponent polymer system, showing the advantage to characterize the complicated multicomponent polymer composite morphologies.