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A sample containing different regions with poly(e-caprolactone) (PCL), oriented polyethylene (PE), and oriented isotactic polypropylene (iPP) films in contact with glass slide has been prepared to be observed in the same view field in an optical microscope and the crystallization of PCL in different regions during cooling from 80 °C down to room temperature at a rate of 1 °C·min−1 was studied. The results showed that the crystallization of PCL started first at the PE surface and then at the iPP surface, while its bulk crystallization occured much later. This indicates that though both PE and iPP are active in nucleating PCL, the nucleation ability of PE is stronger than that of iPP. This was due to a better lattice matching between PCL and PE than that between PCL and iPP. Moreover, since lattice matching existed between every (hk0) lattice planes of both PCL and PE but only between the (100)PCL and (010)iPP lattice planes, the uniaxial orientation feature of the used PE and iPP films resulted in the existence of much more active nucleation sites of PCL on PE than on iPP. This led to the fact that the nucleation density of PCL at PE surface was so high that the crystallization of PCL at PE surface took place in a way like the film developing process with PCL microcrystallites happened everywhere with crystallization proceeding simultaneously. On the other hand, even though iPP also enhanced the nucleation density of PCL evidently, the crystallization of PCL at iPP surface included still a nucleation and crystal growth processes similar to that of its bulk crystallization.

An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly(cyclohexene carbonate) (PCHC) has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point (T m) of 215–230°C and a decomposition temperature of ca. 310°C. The spherulitic morphology of (R)-PCHC grows in a clockwise spiral from a center, and that of (S)-PCHC is a counterclockwise spiral, while the stereocomplex of (S)-PCHC/(R)-PCHC (1/1 mass ratio) presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.

A new method of standard curve analysis associated with X-ray photoelectron spectroscopy (XPS) is presented for measuring the thickness of ultrathin SiO2 layer on Si substrate. In this method, XPS spectra of series SiO2/Si standard samples with different known thicknesses of silicon oxides are firstly recorded, and then the ratios of Si2p peak heights corresponding to SiO2 and Si, viz. R = H(SiO2/H(Si), are calculated. The known thicknesses of silicon oxides are plotted against the peak height ratios and an XPS standard curve is derived. Under the same experimental conditions, the samples with unknown thicknesses are measured by using XPS technique and then their thicknesses can be obtained from the XPS standard curve. The SiO2 /Si standard samples were provided by authoritative lab with the advanced analytical equipments and rich experiences, and the oxide thicknesses were measured by multiple techniques. The present results show that the standard curve, plotted in terms of accuracy of the oxide thickness from the standard samples, can be used for the thickness measurement for ultrathin SiO2 on Si, and this method is valuable in practice owing to the swiftness, convenience and accuracy.