This review covers recent advances in fabrication of nanomaterials in polymer solutions with emphasis on using the self assembled amphiphilic block copolymers in solution to fabricate organic/inorganic composites with...This review covers recent advances in fabrication of nanomaterials in polymer solutions with emphasis on using the self assembled amphiphilic block copolymers in solution to fabricate organic/inorganic composites with nanoscale modifications. The phase behavior of block copolymers in water and the use of templates to form ordered nanostructures are reviewed in detail. Modern physical techniques for nanoscale characterization are also introduced. The authors suggested that this approach should provide new routes to create materials with interesting morphologies for many different applications.展开更多
Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene(sPP) was studied by time-resolved simultaneous small-angle X-ray scattering(SAXS) and wide-an...Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene(sPP) was studied by time-resolved simultaneous small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) methods with synchrotron radiation and differential scanning calorimetry(DSC). The time and temperature dependent parameters such as long period, L , crystal lamellar thickness, l c, amorphous layer thickness, l a, scattering invariant, Q , crystallinity, X c, lateral crystal sizes, L 200 and L 020 , and unit cell parameters a and b were extracted from SAXS and WAXD profiles. Decreasing long period and crystal thickness indicate that thinner secondary crystal lamellae are formed. The decreases in unit cell parameters a and b during isothermal crystallization process suggest that crystal perfection takes place. The changes in the morphological parameters (the invariant, Q , crystallinity, X c, long period, L , and the crystal thickness, l c) during subsequent melting were found to follow a two-stage melting process, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak) and the subsequent recrystallization-melting process(second peak). Additional minor endothermic peak located at the lowest temperature was also detected and might be related to melting of secondary, thinner and defective lamellae. WAXD showed that during melting, thermal expansion was greater along the b axis than that along the a axis.展开更多
基金BC gratefully acknowledges support of this work by the Polymers Program of the National Science Foundation(DMR9984102)by the US Department of Energy(DEFG0286ER45237.O16).
文摘This review covers recent advances in fabrication of nanomaterials in polymer solutions with emphasis on using the self assembled amphiphilic block copolymers in solution to fabricate organic/inorganic composites with nanoscale modifications. The phase behavior of block copolymers in water and the use of templates to form ordered nanostructures are reviewed in detail. Modern physical techniques for nanoscale characterization are also introduced. The authors suggested that this approach should provide new routes to create materials with interesting morphologies for many different applications.
文摘Structure and morphology development during isothermal crystallization and subsequent melting of syndiotactic polypropylene(sPP) was studied by time-resolved simultaneous small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) methods with synchrotron radiation and differential scanning calorimetry(DSC). The time and temperature dependent parameters such as long period, L , crystal lamellar thickness, l c, amorphous layer thickness, l a, scattering invariant, Q , crystallinity, X c, lateral crystal sizes, L 200 and L 020 , and unit cell parameters a and b were extracted from SAXS and WAXD profiles. Decreasing long period and crystal thickness indicate that thinner secondary crystal lamellae are formed. The decreases in unit cell parameters a and b during isothermal crystallization process suggest that crystal perfection takes place. The changes in the morphological parameters (the invariant, Q , crystallinity, X c, long period, L , and the crystal thickness, l c) during subsequent melting were found to follow a two-stage melting process, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak) and the subsequent recrystallization-melting process(second peak). Additional minor endothermic peak located at the lowest temperature was also detected and might be related to melting of secondary, thinner and defective lamellae. WAXD showed that during melting, thermal expansion was greater along the b axis than that along the a axis.
