原位聚合法研制纳米胶囊相变材料

采用超声波工艺及细乳液原位聚合方法,研制了以聚苯乙烯为囊壁、正十八烷为囊芯的纳米胶囊相变材料;系统探讨了聚合反应各因素如引发剂、链转移剂、表面活性剂以及正十八烷/苯乙烯比等对乳胶粒子的形态、胶囊材料热性能的影响,对所研制的胶囊相变材料进行激光衍射粒度分析、透射电镜及差示扫描量热等表征.实验结果表明,在引发剂AIBN 0.5%(油相质量百分比,下同);链转移荆DD在T0.4%;复合乳化剂(SDS/OP10)总量2%,配比1:1及正十八烷/苯乙烯比=1:1条件下,胶囊呈球形均匀分布,聚苯乙烯囊壁能将正十八烷囊芯很好包裹住,其胶囊Z均直径124nm,相变焓可达124.4kJ·kg-1.     

Immobilization of TiO2 nanoparticles on Fe-filled carbon nanocapsules for photocatalytic applications

Using a simple sol-gel method, a novel magnetic photocatalyst was produced by immobilization of TiO₂ nano-crystal on Fe-filled carbon nanocapsules (Fe-CNC). High resolution TEM images indicated that the immobilization of TiO₂ on Fe-CNC was driven primarily by heterogeneous coagulation, whereas surface nucleation and growth was the dominant mechanism for immobilizing TiO₂ on acid-functionalized hollow CNC. The TiO₂ immobilized on Fe-CNC exhibited the anatase phase as revealed by the X-ray diffraction (XRD) patterns. In comparison with free TiO₂ and TiO₂-coated CNC, TiO₂-coated Fe-CNC displayed good performance in the removal of NO gas under UV exposure. Due to the advantages of easy recycling and good photocatalytic efficiency, the novel magnetic photocatalyst developed here has potential use in photocatalytic applications for pollution prevention.     

Preparation of polymeric nanocapsules via nano-sized poly(methoxydiethyleneglycol methacrylate) colloidal templates

Polymeric nanocapsules are attractive devices with a number of potential applications. In the present contribution we describe a method for nanocapsule preparation which is based on the formation of nanosized templates (mesoglobules, prepared from thermo-responsive poly(methoxydiethyleneglycol methacrylate)s, PDEGMA). These mesoglobules were coated with a cross-linked shell formed by pseudo-seeded radical polymerization of either N-isopropylacrylamide or 2-hydroxyethylmethacrylate in the presence of a cross-linking agent. Dissolution and removal of templates were achieved by extensive dialysis against water at temperatures below the LCST of PDEGMA. The obtained nanocapsules were visualized by transmission electron microscopy and their dimensions were determined by dynamic light scattering. The differences in the morphology of the nanocapsules were attributed to the different structures of the cross-linked membranes.     

Confocal laser scanning microscopy to study formation and properties of polyelectrolyte nanocapsules derived from CdCO3 templates

Three-dimensional confocal laser scanning microscopy (CLSM) was used as an essential investigation method to obtain information about the formation and morphological characteristics of nanocapsules. Nanocapsules are built by layer-by-layer deposition of alternatively charged polyelectrolytes on templates forming nanostructured hollow shells. CLSM is unique in allowing for monitoring of the core dissolution process in real time and for studying nanocapsule functioning in hydrated conditions within a three-dimensional and temporal framework. Since we are also interested in the identification of other possible templates, we briefly report on the use of yeast cells as biocolloidal cores monitored by means of two-photon microscopy. Here we focus our attention on the use of CdCO(3) crystals as template candidates for the preparation of stable capsules. Both cubic and spherical CdCO(3) cores have been produced. Cubic cores exhibit higher monodispersity and smaller size compared to spherical ones. Capsules templated on these cores have a higher surface-to-volume ratio that is valuable for applications related to drug delivery, functional properties of the shells and adsorption of proteins, and other biologically relevant molecules. Microsc. Res. Tech. 59:536-541, 2002.     

Ultrastable Liquid–Liquid Interface as Viable Route for Controlled Deposition of Biodegradable Polymer Nanocapsules

Liquid–liquid interfaces are highly dynamic and characterized by an elevated interfacial tension as compared to solid–liquid interfaces. Therefore, they are gaining an increasing interest as viable templates for ordered assembly of molecules and nanoparticles. However, liquid–liquid interfaces are more difficult to handle compared to solid–liquid interfaces; their intrinsic instability may affect the assembly process, especially in the case of multiple deposition. Indeed, some attempts have been made in the deposition of polymer multilayers at liquid–liquid interfaces, but with limited control over size and stability. This study reports on the preparation of an ultrastable liquid–liquid interface based on an O/W secondary miniemulsion and its possible use as a template for the self‐assembly of polymeric multilayer nanocapsules. Such polymer nanocapsules are made of entirely biodegradable materials, with highly controlled size—well under 200 nm—and multi‐compartment and multifunctional features enriching their field of application in drug delivery, as well as in other bionanotechnology fields.