光致变色微胶囊的制备与性能

以蜜胺树脂为壁材、光致变色材料为芯材,采用原位聚合法制备了具有光致变色性能的微胶囊.研究了三聚氰胺/甲醛摩尔比、壁材与芯材的用量比、乳化剂浓度等因素对微胶囊形貌及性能的影响.在最佳工艺条件下制备的变色微胶囊,在日光和紫外光下具有快速、可逆的光致变色性能.     

Motion of compliant capsules on corrugated surfaces: A means of sorting by mechanical properties

We discuss a novel method for capturing the dynamic coupling between a fluid and an elastic solid, the so-called fluid–structure interaction. This method integrates a lattice Boltzmann model to capture the fluid dynamics with a lattice spring model to capture the micromechanics of the solid phase. We then examine the fluid-driven motion of microcapsules, which are modeled as fluid-filled, elastic shells, along a corrugated substrate. We show that the ability of the capsules to navigate along the surface depends critically on capsule's elastic modulus. In particular, we illustrate how this substrate can be utilized to design a device for sorting microcapsules by their mechanical properties. These results apply not only to polymeric microcapsules, but also describe the interaction between the substrate and certain biological cells (e.g., leukocytes and other cells with cytoskeletons). Hence, by isolating species of a certain stiffness, the device could be highly useful for applications in biotechnology and tissue engineering or in the quality control of fabricated microcapsules. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2667–2678, 2006     

Surface Modification of Poly(urea-formaldehyde) Microcapsules and the Effect on the Epoxy Composites Performance

The surfaces of poly(urea-formaldehyde) (PUF) were modified by γ -glycidoxypropyltrimethoxy silane (KH560) in order to improve the interfacial bonding between self-healing PUF microcapsules and epoxy matrix. The modification mechanism between PUF microcapsules and KH560 was studied. X-ray photoelectron spectra (XPS) analyses showed that the silane coupling agent molecular binds strongly to the surfaces of PUF microcapsules. Chemical bond (Si–O–C) and hydrogen bond were formed at interface by the reaction between Si–OH and the hydroxyl group of PUF microcapsules surface. The tensile and impact resistance tests revealed that strength and toughness of the composites was improved significantly. Furthermore, scanning electronic microscopy (SEM) photographs of the fractured surface confirmed that the silane coupling agent plays an important role in improving the interfacial performance between microcapsules and resin matrix.     

十八烷/聚(St-MMA)相变微胶囊制备及表征

采用乳液聚合的方法,分别选取聚苯乙烯(PS)、聚甲基丙烯酸甲酯(PMMA)或苯乙烯和甲基丙烯酸甲酯的共聚物为壁材,正十八烷为芯材,十二烷基苯磺酸钠(SDBS)为乳化剂,制作相变储能微胶囊。用粒径分析仪、透射电子显微镜(TEM)、热重分析仪(TG)和示差扫描量热测试仪(DSC)对微胶囊的形貌、相变热性能和热稳定性分别进行表征。结果表明:壁材选取两者共聚物,当两种单体的比例为St∶MMA=1∶5,SDBS用量为1.5g(总质量的3%)时,微胶囊粒径大小均匀,粒子分散性好,壁材的包裹性好。微胶囊的放热峰为起始温度为27.3℃,终止温度为31.9℃,相变温度为28.9℃,相变焓为48.4J/g。TG表明长期使用温度不能超过131℃。IR分析微胶囊中含有芯材和壁材。这种十八烷/聚(St-MMA)相变微胶囊可以用于诸能材料。     

Reconfigurable Photonic Capsules Containing Cholesteric Liquid Crystals with Planar Alignment

Cholesteric liquid crystals (CLCs) reflect selected wavelengths of light owing to their periodic helical structures. The encapsulation of CLCs leads to photonic devices that can be easily processed and might be used as stand‐alone microsensors. However, when CLCs are enclosed by polymeric membranes, they usually lose their planar alignment, leading to a deterioration of the optical performance. A microfluidics approach was employed to integrate an ultrathin alignment layer into microcapsules to separate the CLC core and the elastomeric solid membrane using triple‐emulsion drops as the templates. The thinness of the alignment layer provides high lubrication resistance, preserving the layer integrity during elastic deformation of the membrane. The CLCs in the microcapsules can thus maintain their planar alignment, rendering the shape and optical properties highly reconfigurable.     

Near‐Infrared‐Activated Nanocalorifiers in Microcapsules: Vapor Bubble Generation for In Vivo Enhanced Cancer Therapy

Photothermal therapy based on gold nanostructures has been widely investigated as a state‐of‐the‐art noninvasive therapy approach. Because single nanoparticles cannot harvest sufficient energy, self‐assemblies of small plasmonic particles into large aggregates are required for enhanced photothermal performance. Self‐assembled gold nanorods in lipid bilayer‐modified microcapsules are shown to localize at tumor sites, generate vapor bubbles under near‐infrared light exposure, and subsequently damage tumor tissues. The polyelectrolyte multilayer enables dense packing of gold nanorods during the assembly process, which leads to the formation of vapor bubbles around the excited capsules. The resulting vapor bubbles achieve a high efficiency of suppressing tumor growth compared to single gold nanorods. In vivo experiments demonstrated the ability of soft‐polymer multilayer microcapsules to cross the biological barriers of the body and localize at target tissues.     

Novel ultrasound contrast agents——Biodegradable poly(lactic acid) microcapsules

The different intensities of reflecting and scattering ultrasound signal at the tissue interface of the body can help to deliver the inner information and have proven their tremendous usefulness in medicine. Because it has a lot of advantages such as safety, wide application, good repetition, effi-cient detection, flexibility and economy, ultrasound diagnostics becomes the primary technology of modern medical imaging diagnostics and plays a key role in the modern diagnostic technol-ogy[1]. Alt…     

An orally administered microcapsule system for treating chronic renal failure patients

Ingestible adsorbents for the removal of uremic metabolites are being investigated as adjunctive therapy in the treatment of chronic uremia. In particular, a microcapsule product containing urease and zirconium phosphate (UZP) has been investigated for removing urea. A dog model, simulating chronic uremia, was developed to investigate: (1) the concentration of various nitrogenous metabolites (urea, creatinine, and uric acid) in the GI tract, (2) flux rates of H₂O and various nitrogenous metabolites in the GI tract, and (3) the efficacy of the microcapsule product. The results of these perfusion studies suggest that urea and creatinine can be removed from the GI tract via ingestible adsorbents. In addition, the model may be useful in investigating suspect uremic toxins, e.g., guanidinosuccinic acid (GSA). The reduction of blood urea nitrogen levels in the dog model when the animal was fed the microcapsule product was limited by the capacity of the zirconium phosphate to bind ammonium ion. Preliminary clinical studies with the microcapsule product indicate that it may be of potential adjunctive therapy in patients suffering from chronic renal failure.     

A novel immobilized-enzyme system utilizing microcapsules

A novel immobilized-enzyme system that has glucoamylase on the surface of, and glucose oxidase within, polyurea microcapsules was developed. This system was found to carry out its sequential enzymatic reaction effectively. It was also demonstrated that the use of microcapsules was useful for this immobilized-enzyme system since a large amount of the second enzyme, glucose oxidase, was required for the sequential reaction to proceed efficiently. In addition, this system was found helpful for making the size of reaction batches smaller.