We report a novel approach to continuous and scalable production of core-shell droplets and polymer capsules in microfluidic devices. The described method is also useful in the synthesis of polymer particles with nonspherical shapes. We used capillary instability-driven break-up of a liquid jet formed by two immiscible fluids. Precise control of emulsification of each liquid allowed for the production of highly monodisperse core-shell droplets with a predetermined diameter of cores and thickness of shells. We also achieved control over the number of cores per droplet and the location of cores in the droplet. We carried out fast throughput photopolymerization of the monomeric shells and obtained polymer particles with various shapes and morphologies, including spheres, truncated spheres and, hemispheres, and single and multicore capsules. 相似文献
This article provides an overview of our work in the area of the synthesis of polymer particles in continuous microfluidic reactors. The method includes (a) the generation of highly monodisperse monomer droplets in a microfluidic flow-focusing device and (b) in-situ solidification of these droplets by means of photopolymerization. We discuss the effect of monomer properties on the emulsification process, the effect of the polymerization rate on the production of high-quality particles, the role of the material of the microfluidic device in droplet formation, and the synthesis of particles with different shapes and compositions. We also demonstrate the production of highly ordered arrays of polymer particles achieved by photopolymerization of the dynamic lattices of monomer droplets in microfluidic channels. The article is concluded with a summary of future research directions in the production of polymer colloids in microfluidic reactors. 相似文献
A new bulk acoustic wave (BAW) sensor modified with a molecularly imprinted polymer (MIP) was fabricated and applied for the determination of pyrimethamine. This sensor exhibited high selectivity and sensitive response to pyrimethamine. Factors such as pH and the amount of coating influencing sensor properties, were investigated in detail and optimized. The calibration curve was linear in the range 6.0x10(-7)-1.0x10(-4) M. The determination limit was 2.0x10(-7) M. In harsh chemical environments such as high temperature, organic solvents, bases, acids, etc., the sensor still exhibited long-term stability. The proposed method has been satisfactorily applied for the determination of pyrimethamine in serum and urine media. 相似文献
The electron impact mass spectra of several cyclic esters with helical structures have been studied. Their fragmentation pathways were proposed and confirmed by mass-analyzed ion kinetic energy (MIKE) and high-resolution data. In general, the dominant fragmentation pathways in the spectra of these compounds originate from a alpha-cleavage with loss of a hydrogen or methyl group. The difference between hydrogen and methyl group loss greatly affects the subsequent fragmentations. Although, due to their helicity, these cyclic esters are optically active no stereo-related fragmentation pathway was observed. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
Crosslinked chitosan-based nanofibers were successfully prepared via electrospinning technique with heat mediated chemical crosslinking followed.The structure,morphology and mechanical property of nanofibers were characterized by attenuated total reflection-Fourier transform infrared spectroscopy(ATR-FTIR),scanning electron microscopy(SEM),Instron machine,respec- tively.The results showed that,nanofibers exhibited a smooth surface and regular morphology,and tensile strength of nanofibers improved with increasing of triethylene glycol dimethacrylate(TEGDMA)content. 相似文献
Perovskite formamidinium lead triiodide (FAPbI3) is a very promising photovoltaic material. Unfortunately, perovskite FAPbI3 converts to a hexagonal phase at ambient conditions. Herein we study the electronic structure of both perovskite and hexagonal FAPbI3 films using soft X‐ray absorption near edge structure (XANES) and density functional theory. We find that the C and N 2p states of FA hybridize with the Pb, I states at the conduction band minimum in hexagonal, but not perovskite, FAPbI3. We also demonstrate that C K‐edge XANES can be used to investigate shifts in the valence band in other organic‐inorganic hybrid perovskites.
Graphical summary of the electronic structure and C K‐edge XANES in both perovskite and hexagonal FAPbI3 highlighting our findings. 相似文献
Knowledge on the interactions between engineered nanomaterials (ENMs) and biological systems is critical both for the assessment of biological effects of ENMs and for the rational design of ENM-based products. However, probing the events that occur at the nano-bio interface remains extremely challenging due to their complex and dynamic nature. So far, the understanding of mechanisms underlying nano-bio interactions has been mainly limited by the lack of proper analytical techniques with sufficient sensitivity, selectivity and resolution for characterization of nano-bio interface events. Moreover, many classic bioanalytical methods are not suitable for direct measurement of nano-bio interface interactions. These have made establishing analytical methodologies for systematic and comprehensive study of nano-bio interface one of the most focused areas in nanobiology. In this review we have discussed some representative developments regarding analytical techniques for nano-bio interface characterization, including the improvements of traditional methods and the emergence of powerful new technologies. These developments have allowed ultrasensitive, real-time analysis of interactions between ENMs and biomolecules, transformations of ENMs in biological environment, and impacts of ENMs on living systems on molecular or cellular level. 相似文献