A series of well-defined core cross-linked star (CCS) polymeric ionic liquids (PILs) were synthesized via a three-step approach. First, the styrenic imidazole-based CCS polymer (S-PVBnIm) was prepared by the RAFT-mediated heterogeneous polymerization in a water/ethanol solution, followed by the quaternization of S-PVBnIm with bromoalkanes and anion exchange. The CCS polymers were characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The obtained CCS polymers were used as the effective emulsifiers for oil-in-water high internal phase emulsions (HIPEs). Multiple oils with different polarity including n-dodecane, undecanol, toluene and octanol were emulsified using 0.5 wt% S-PVBnIm aqueous solution under the acidic condition to form HIPEs with long-term stabilities. The excellent emulsification properties of CCS PILs were demonstrated by HIPE formation for a variety of oils. The properties of HIPEs in terms of emulsion type and oil droplet size were characterized by the confocal laser scanning microscopy (CLSM). The intriguing capability of CCS PILs to stabilize HIPEs of various oils holds great potentials for the practical applications. 相似文献
Molecular surface-imprinted polymers nanoparticles encapsulating magnetite modified with oleic acid, for recognition of salicylic acid was prepared by three-step miniemulsion polymerization. The important factors including polymerization process, solvents, miniemulsifying approaches, and co-stabilizer have been investigated to obtain magnetic molecular imprinting polymers (MMIPs) nanoparticles (NPs) with high saturation magnetization (Ms), regular morphology, and good monodispersion. The results showed that the amount of magnetite encapsulated in MMIPs NPs was 43.4 wt% and Ms was 33.584 emu/g. Thus, MMIPs NPs could be separated easily within 2 minutes by an external magnetic field. The transmission electron microscope (TEM) showed MMIPs NPs were of regular sphere with core-shell structure, where magnetite NPs were uniformly encapsulated in homogeneous polymer shells. The average diameter of MMIPs NPs was 98 nm with RSD of 6.6%. Good recognition and high loading of target molecule were achieved by MMIPs NPs in batch rebinding tests. 相似文献
Inspired by natural porous materials, such as wood, bamboo and spongy bone consisting of individual structural units that are hierarchically arranged to optimise mechanical properties such as strength and toughness, synthetic macroporous polymers with enhanced physical properties were created by emulsion templating. Hierarchical poly(merised) high internal phase emulsions (HIPE) were created from HIPEs stabilised simultaneously by particles and a surfactant. In these HIPEs, surfactant stabilised and particle stabilised water droplets coexist, which upon polymerisation of the minority oil phase gives rise to macroporous polymers with a hierarchical pore structure. An improvement of the mechanical properties of our hierarchically structured macroporous polymers at equal porosity was observed, due to a more efficient packing of pores in a configuration that improves mechanical strength despite the presence of interconnecting pore throats. Moreover, the permeability of the hierarchically structured polyHIPEs are exceeding those measured for conventional polyHIPEs made from surfactant only stabilised HIPEs.
The formation of hierarchical porous protein scaffolds from oil‐in‐water (o/w) high internal phase emulsions (HIPEs) stabilized by bovine serum albumin (BSA) protein nanoparticles (Pickering HIPE) is reported. The route consists of three principal steps. First, a stable o/w HIPE stabilized by BSA protein nanoparticles is formulated. Next, crosslinking the dispersed protein nanoparticles gives rise to a gel in the continuous water phase to freeze the emulsion's microstructure. Finally, removal of the oil components and water directly leads to a three dimensional, bimodal meso‐macroporous protein scaffold, which is suitable for a wide range of biomedical applications. 相似文献
Core-shell particles with cross-linked core and shell were used as seed particles to produce composite Janus particles. It was found that when the shell has distinctly higher cross-linking degree than the core, Janus particles with very unusual structures can be obtained. These particles have two parts, with one part embraced partially or entirely by the other part, adjustable by parameters such as phase ratio or cross-linking degree. On the basis of experimental observations, a possible mechanism for the formation of such unusual Janus particles has been proposed. Janus particles with arms are used to emulsify water-toluene mixtures, forming oil-in-water (O/W) emulsions at very high internal phase content with rather low concentration of particles. Nonspherical emulsion droplets were observed, indicating that these Janus particles are likely to jam at the interface, forming a strong protecting layer to stabilize emulsions. 相似文献
Poly(styrene-co-methacrylic acid) (PS-co-MAA) particles were synthesized via surfactant-free emulsion polymerization and then used as particulate emulsifiers for preparation of Pickering emulsions. Our results showed that adjusting the solution pH can tune the wettability of PS-co-MAA particles to stabilize either water-in-oil (W/O) or oil-in-water (O/W) Pickering emulsions. Stable W/O emulsions were obtained with PS-co-MAA particles at low pH values due to their better affinity to the dispersed oil phase. In contrast, increasing the pH value significantly changed the stabilizing behavior of the PS-co-MAA particles, leading to the phase inversion and formation of stable O/W emulsions. We found that the oil/water ratio had a significant influence on pH value of the phase inversion. It decreased with decreasing the oil/water ratio, and no phase inversion occurred when the styrene volume fraction reduced to 10 %. Additionally, macroporous polystyrene (PS) foam and PS microspheres were obtained via polymerization of Pickering high internal phase emulsion (Pickering HIPE) and O/W Pickering emulsion, respectively. 相似文献
The mechanical dispersion technology used in this study employs rotor-stator mixers that produce water-continuous high internal phase emulsions (HIPEs) with narrow drop size distributions and small drop sizes, even when the internal phase (oil) viscosity is quite high. Analysis of these HIPEs reveals trends that are consistent with formation by a capillary instability mechanism in which a shear deformation produces highly elongated drops that rupture to form uniform, small droplets. In the search for a predictive tool to aid in the manufacture and use of HIPEs, rheology data for these shear-thinning HIPEs have been compared to data for models in the literature. Existing models do not correctly account for the effect of a high internal phase viscosity on the rheological properties of the HIPE. Another shortcoming is failure to correctly address the shear-thinning exponent. Whereas internal phase viscosity does not seem to affect the shear-thinning exponent, the surfactant apparently plays an important role, possibly through its modification of the interfacial tension and continuous phase rheology. 相似文献
A versatile method to prepare non‐covalently crosslinked polyHIPEs hydrogels from oil‐in‐water high internal phase emulsions (HIPEs) whose aqueous phase contained thermo‐responsive linear polymers is described. The interconnected pore structure of the polyHIPEs is maintained by reversible physical aggregation of thermo‐responsive polymer chains in an aqueous environment. This method to prepare interconnected porous hydrogels using a thermal trigger in the guise of thermo‐responsive polymers by emulsion templating requires no chemical reaction during solidification of the template. This particular feature could provide a safer route to injectable scaffolds as issues of polymerisation/crosslinking chemistry and residual initiator fragments or monomers do not arise 相似文献
Metal‐organic frameworks (MOFs) nanoparticles in combination with a nonionic surfactant (Pluronic L‐121) are used to stabilize dicyclopentadiene (DCPD)‐in‐water high internal phase emulsions (HIPEs). The resulting HIPEs containing the MIL‐100(Fe) nanoparticles (MIL: Materials of Institut Lavoisier) at the interface between the oil‐ and the water‐phases are then cured, and 100 μm thick, fully open, hierarchically porous hybrid membranes are obtained. The properties of the MIL‐100(Fe)@pDCPD polyHIPE membranes are characterized and it is found that up to 14 wt% of the MIL‐100(Fe) nanoparticles are incorporated in the hybrid material resulting in an increase of the microporosity up to 130 m2 g−1. Hybrid membranes show an appealing catalytic activity in Friedel–Crafts alkylation in a batch mode as well as in a flow‐through mode, thereby demonstrating the preserved accessibility of Lewis acidic sites in the MOF nanostructures.
New oil-in-alcohol highly concentrated emulsions were formulated and were used as a templates to obtain macroporous poly(furfuryl alcohol) monoliths by a one-step method. The oil-in-alcohol highly concentrated emulsions were prepared by stepwise addition of the oil phase to the surfactant-alcohol solution and were characterized by optical microscopy and by laser diffraction. The typical structure of highly concentrated emulsions, with close-packed polyhedral droplets, has been observed. Poly(furfuryl alcohol) monoliths were obtained by polymerizing in the external phase of these emulsions. These materials are mainly macroporous and retain the size distribution and morphology from the highly concentrated emulsions. The internal structure of the monoliths was observed by scanning electron microscopy. The images showed an interconnected network with pore size similar to the droplet size of the highly concentrated emulsions used as templates. 相似文献
We herein present a novel and simple synthetic strategy for fabricating multihollow superparamagnetic magnetite/polystyrene nanocomposite microspheres via water-in-oil-in-water double emulsions. Amphipathic magnetite nanoparticles surface-modified with oleic acid act as an oil-soluble emulsifier and sodium dodecyl sulfate acts as a water-soluble surfactant in the system. The final products were thoroughly characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy, which showed the formation of multihollow magnetite/polystyrene nanocomposite microspheres. Preliminary results of magnetic properties of multihollow magnetite/polystyrene microspheres were reported. The effect of the content of amphipathic magnetite nanoparticles on the morphology of nanocomposite microspheres was studied. Furthermore, the mechanism of formation of multihollow magnetic nanocomposite microspheres was also discussed. 相似文献
Hydrophobin coated boehmite nanoparticles have been used to establish tooth-paste like, homogenous emulsions. The surface-modified nanoparticles were simply obtained by mixing aqueous solutions of cationic boehmite particles with the anionic hydrophobin H Star Protein B® (HPB). Surface tension measurements clearly show that 1 wt.% boehmite binds up to 1 wt.% HPB. The strong interaction and aggregation of hydrophobin coated boehmite nanoparticles was proven by Cryo-TEM measurements, too. Interestingly, the combined use of 0.5 wt.% HPB and 0.5 wt.% boehmite as emulsifying agents resulted in very stable, homogenous, high internal phase emulsions (65 wt.% oil) that are stable over months. The established emulsions have also been characterized by rheological measurements. Storage moduli of more than 1000 Pa are characteristic for their high gel-like properties. Furthermore, light microscopy showed an average droplet size close to 1 μm with low polydispersity. Cryo-SEM confirmed that the hydrophobin coated nanoparticles are located at the interface of the oil droplets and therefore stabilize the emulsion systems. 相似文献
Due to intermediate hydrophobicity of methyl methacrylate (MMA) monomer in water, it is difficult to prepare its stable water in oil high internal phase emulsion (HIPE). Moreover, the addition of fully hydrophilic co-monomer such as 2-hydroxyethyl methacrylate (HEMA) in MMA monomer makes it further troublesome to stabilize these emulsions. This paper addresses the preparation of such type of difficult to prepare emulsions via addition of an amphiphilic fluorinated di-block copolymer (FDB), poly(2-dimethylamino)ethylmethacrylate-b-poly(trifluoroethyl methacrylate) (PDMAEMA-b-PTFEMA) as stabilizer. Interestingly, HEMA and/or HFBA (hexa fluorobutyl acrylate) as co-monomers were successfully added to impart some special properties such as thermodynamic stability, desired amphiphilicity to the final polyHIPEs. Fluorinated blocks in FDB anchored well at oil/water interface of HIPE, offering enough hydrophobicity to the comparatively hydrophilic monomers and in turn providing resistance against coalescence. MMA polyHIPEs were found to be fully hydrophobic just by replacing HEMA co-monomer with HFBA. Due to superb inherent hydrophobic nature of fluorine atoms, MMA-HFBA polyHIPEs showed remarkable water contact angle of 139°. Furthermore, the addition of fluorinated co-monomer in MMA based HIPEs significantly improved thermal stabilities of these materials with improvement in degradation temperature from 305 °C to 360 °C. 相似文献