用于合成纳米苯丙乳液的纳米TiO2表面改性及表征

研究了利用硅烷偶联剂改性纳米TiO2的方法,并通过FTIR、TEM等手段表征化学改性产物的结构和改性后纳米二氧化钛的分散性,结果表明偶联剂与二氧化钛表面发生化学偶联反应,使二氧化钛表面被偶联剂包覆,从而使二氧化钛改性产物在有机物中具有良好的分散性能.通过TEM分析用改性后的纳米TiO2原位合成的纳米TiO2/苯丙乳液复合体系具有以纳米TiO2粒子为核,以聚合物为壳的核壳结构,该乳液涂膜的耐水性达120h不泛白,硬度为H级,明显优于非纳米苯丙乳液,且具有很好的抑菌作用,可用于制备纳米水性涂料.     

纳微米颗粒的表面改性及其在Pickering乳液中的应用进展

以固体粒子替代表面活性剂稳定的Pickering乳液,不仅可以赋予乳液许多特殊的性能(电磁和温度感应性能等),还可消除由添加表面活性剂所带来的副作用(过敏性和毒性等),这使得Pickering乳液可以应用到对表面活性物质具有很大限制的生物材料领域。系统综述了常见Pickering乳液用固体粒子,以及为了获得不同类型的乳液而对固体粒子进行表面改性的主要方法,着重归纳了表面改性前亲水性羟基磷灰石(HAp)和改性后疏水性HAp作为颗粒乳化剂稳定的Pickering乳液的类型及其进一步合成的产物。     

油酸修饰对纳米二氧化钛在变压器油中分散性的影响

利用油酸对纳米二氧化钛进行有机表面修饰, 将修饰后的纳米粉体超声分散到变压器油中制备纳米二氧化钛改性变压器油, 研究了表面修饰对纳米二氧化钛在变压器油中分散性的影响. 采用X射线粉末衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热分析(TG)对纳米二氧化钛的形貌、结构和表面修饰状态进行表征。结果表明, 油酸与纳米二氧化钛表面以双齿桥连配位方式键合, 在纳米二氧化钛表面形成了良好的修饰层。随着修饰剂的增加, 尽管油酸在纳米二氧化钛表面的配位方式没有发生改变, 但化学包覆量明显增加, 表面油酸分子的排列也更为紧密, 从而使纳米二氧化钛粒子在变压器油中的分散性和稳定性显著提高。当钛盐与油酸摩尔比为1:24时, 二氧化钛纳米粒子可以稳定分散在变压器油中, 室温静置30 d后仍保持澄清透明。     

细乳液聚合法制备双相核材料的电子墨水纳胶囊

摘要：利用细乳液法制备包含炭黑纳米颗粒／TiO2纳米颗粒和分散剂[四氯乙烯（TEC）和SPAN-80的混合液]的双相核材料的电子墨水纳米胶囊。以苯乙烯（SM）-甲基丙烯酸甲酯（MMA）为反应单体,十六烷（HD）为疏水剂,偶氮二异丁腈（AIBN）为引发剂,聚乙烯醇（PVA）为表面活性剂,乙醇为溶剂。把分别包含TiO2有机...     

Control of Particle Adsorption for Stability of Pickering Emulsions in Microfluidics

Studying the stability of Pickering emulsion is of great interest for applications including catalysis, oil recovery, and cosmetics. Conventional methods emphasize the overall behavior of bulk emulsions and neglect the influence of particle adsorbing dynamics, leading to discrepancies in predicting the shelf‐life of Pickering emulsion–based products. By employing a microfluidic method, the particle adsorption is controlled and the stability of the Pickering emulsions is consequently examined. This approach enables us to elucidate the relationship between the particle adsorption dynamics and the stability of Pickering emulsions on droplet‐level quantitatively. Using oil/water emulsions stabilized by polystyrene nanoparticles as an example, the diffusion‐limited particle adsorption is demonstrated and investigated the stability criteria with respect to particle size, particle concentration, surface chemistry, and ionic strength. This approach offers important insights for application involving Pickering emulsions and provides guidelines to formulate and quantify the Pickering emulsion–based products.     

Modified coconut pulp particles: The potential candidate for stabilizing Pickering emulsions

Coconut pulp, a by-product of coconut milk extraction, was used to prepare Pickering emulsion–stabilizing particles by modification with citric acid (CA) through dry heat treatment. The treatment temperature (100, 120, and 140 °C) and CA concentration (0.7, 2.0, and 3.3 % w/v) were varied. Modification at 100 °C and high concentration of CA gave products with satisfactory appearance and surface characteristics. The product obtained by treatment at 3.3 % CA and 100 °C had a yellowish white color with a light and porous surface, 0.08 degree of substitution (DS), 70° water contact angle, −50 mv zeta potential, and an average particle size after homogenization of 8.4 µm. Unmodified CP powders could not stabilize the oil-in-water (O/W) emulsion, and phase separation occurred rapidly at 25 °C, while CP modified using 2.0 % and 3.3 % CA at 100 °C could stabilize the emulsion for at least 30 d. The oil droplet size decreased as the DS of the particles increased from 77.3 to 33.3 µm and 18.6 µm for the particles with DS of 0.046, 0.072, and 0.082, respectively. The higher hydrophobicity imparted by CA modification strongly affected the oil droplet size, while the negative surface charge of particles supported the uniform dispersion of free CP particles in the interspace among the oil droplets.     

纳米纤维素凝胶微粒及其在Pickering泡沫中的应用

目的研究氧化纳米纤维素/乳酸链球菌素(TONCC/nisin)凝胶粒子的性质及其在环保抗菌泡沫中的应用。方法利用TONCC的表面羧基基团与nisin的表面阳离子的吸附耦合作用,制备TONCC/nisin水凝胶和微凝胶,以微凝胶作为稳定粒子,环氧大豆油丙烯酸酯(AESO)为油相,制备TONCC/nisin/AESO Pickering乳液,对水凝胶、微凝胶、乳液的稳定性进行研究;通过热固化乳液得到环保抗菌的泡沫材料,并对泡沫材料的结构和抗菌效果进行表征。结果水凝胶的结构随着在水中浸泡时长的增加而发生变化,宏观表现为坍塌变形,nisin逐渐析出,微凝胶随着静置时间的延长其粒径变化不大;以微凝胶作为界面稳定剂的AESO乳液的热稳定性较好,在90℃下加热30 min乳液液滴并未发生聚并现象,该乳液固化后形成的多孔泡沫材料对李斯特菌的抑制作用明显,当泡沫中nisin含量为2μg/g时,其抑菌率为43%。结论TONCC和nisin形成的微凝胶粒子在水中稳定性较好,可以用于乳化AESO制备Pickering泡沫,同时赋予泡沫多孔性和抗菌性,在制备环保抗菌泡沫方面有很大的应用潜力。     

Drying oil-in-water Pickering emulsions to make redispersible powders

We report on the formation of powder by drying oil-in-water emulsions stabilized by silanised silica nanoparticles. Drying was achieved by spraying fine droplets (up to a hundred micrometres in diameter) of the emulsions into a chamber of hot, flowing air. We show that the surfaces of droplets of the emulsions become enriched with nanoparticles as the water evaporates in the drying chamber. Controlling the relative amounts of oil and particles in the droplets being dried is the key to encapsulating the oil drops within the powder. Dried Pickering emulsions containing up to 40 wt% encapsulated oil that could be dispersed in water as drops of the same size as in the original emulsion were produced.     

硅烷偶联剂对纳米二氧化钛表面改性的研究

利用硅烷偶联剂（KH-570）对表面包覆氧化硅的金红石相纳米TiO2进行了有机表面改性．采用红外光谱（IR）、X射线光电子能谱（XPS）、热分析（TG-DTA）、透射电镜（TEM）和润湿性实验等分析手段对表面改性前后的纳米TiO2进行了表征．红外光谱和X射线光电子能谱表明，KH-570以化学键合的方式结合在纳米TiO2的表面，并形成了有机包覆层．经测量，纳米TiO2表面包覆的KH-570的质量分数约为7．42％-8．59％．润湿性实验显示，经KH-570表面改性的纳米TiO2具有疏水性．力学性能实验表明，经KH-570表面改性的纳米TiO2能同时提高复合材料的强度和韧性．     

Synthesis of SiO2-coated Bi2S3/poly(styrene) nanocomposites by in-situ polymerization

New nanocomposites containing silica-coated Bi2S3 nanofibers were synthesised by in situ polymerization using two distinct synthetic strategies: emulsion and suspension polymerization. Transmission and scanning electron microscopy of the nanocomposite particles showed that in both cases the Bi2S3/SiO2 nanoparticles were densely coated with poly(styrene). In situ emulsion polymerization afforded nanocomposites in which the nanofibers were coated with polymer spheres whilst suspension polymerization gives rise to a homogeneous polymer layer coat. The morphology of the poly(styrene) coating observed is discussed considering the surface modification of the nanofibers and the polymerization technique involved.     

Design of microencapsulated phase change material by one-step swelling polymerization in Pickering emulsion

Microencapsulated phase change materials (MePCMs) based on swelling polymerization in Pickering emulsion were demonstrated. Monodisperse poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) P(GMA-co-HEMA) particles were prepared by dispersion polymerization. The introduction of hydrophilic monomer HEMA endowed the obtained particles with suitable surface hydrophilicity for stabilizing Pickering emulsion. MePCMs with PGMA–polystyrene interpenetrating composite shell were formed when non-crosslinked particles were employed as stabilizer, while MePCMs with particles-embedded shell were prepared with crosslinked particles as Pickering stabilizer. Phase change property, thermal stability and thermal reliability of two kinds of MePCMs were investigated by TGA, FT-IR, DSC and cycling test. The temperature of 10% weight loss of MePCMs with interpenetrating shell was 11 °C higher than that of MePCMs with particles-embedded shell. After cycling test, the percentage of leached core materials from MePCMs with interpenetrating shell was approximately one-third of that from MePCMs with particles-embedded shell. The results showed that MePCMs with an integral shell presented better thermal stability, tightness and thermal reliability than MePCMs with particles-embedded shell. The research developed a simple process for MePCMs with excellent performance.     

化学修饰对Fe3O4磁性微球性能的影响

采用部分还原沉淀法制备了Fe3O4磁性微球,并用硅烷偶联剂对其进行了表面修饰.利用X-射线衍射(XRD)、透射电子显微镜(TEM)、原子力显微镜(AFM)、红外光谱(IR)和分光光度计等手段对其结构和性能进行了表征和测量,研究了硅烷偶联剂对磁性纳米微球性能的影响.结果表明,修饰后的磁性纳米微球具有良好的分散性和磁响应性,并且在强酸环境中具有良好的稳定性.经不同硅烷偶联剂修饰后的微球表面可带有-OH,-NH2,-NH,-C=O,-C=C等多种有机功能基团.     

Preparation and characterization of the transparent hybrids of silicone epoxy resin and titanium dioxide nanoparticles via sol-gel reactions

In order to prepare transparent hybrid films of high refractive index, nanoparticles of TiO2 were prepared and dispersed in a silicone epoxy (SE) resin synthesized from diphenyl silane diol and [2-(3,4-epoxycyclohexyl)ethyl] trimethoxysilane by sol-gel reactions. It was found that amorphous TiO2 nanoparticles of about 5 nm modified with hexahydro-4-methyl phthalic anhydride [HMPA] were dispersed in the SE resin without agglomerations. The refractive index of the hybrids increased linearly with increasing the TiO2 contents. The hybrid containing 30 wt% of the TiO2 particles showed light transmittance of 94% at 450 nm and refractive index of 1.63. The fine dispersion of the TiO2 nanoparticles was attributable to the sol-gel reactions between the SE resin and TiO2 nanoparticles and the modification of the TiO2 particles with HMPA.     

Dynamically Reconfigurable,Multifunctional Emulsions with Controllable Structure and Movement

Dynamically reconfigurable oil‐in‐water (o/w) Pickering emulsions are developed, wherein the assembly of particles (i.e., platinum‐on‐carbon and iron‐on‐carbon particles) can be actively controlled by adjusting interfacial tensions. A balanced adsorption of particles and surfactants at the o/w interface allows for the creation of inhomogeneity of the particle distribution on the emulsion surface. Complex Pickering emulsions with highly controllable and reconfigurable morphologies are produced in a single step by exploiting the temperature‐sensitive miscibility of hydrocarbon and fluorocarbon liquids. Dynamic adsorption/desorption of (polymer) surfactants afford both shape and configuration transitions of multiple Pickering emulsions and encapsulated core/shell structured can be transformed into a Janus configuration. Finally, to demonstrate the intrinsic catalytic or magnetic properties of the particles provided by carbon bound Pt and Fe nanoparticles, two different systems are investigated. Specifically, the creation of a bimetallic microcapsule with controlled payload release and precise modulation of translational and rotational motions of magnetic emulsions are demonstrated, suggesting potential applications for sensing and smart payload delivery.     

Hybrid Organic–Inorganic Colloidal Composite ‘Sponges’ via Internal Crosslinking

An effective method for the generation of hybrid organic–inorganic nanocomposite microparticles featuring controlled size and high structural stability is presented. In this process, an oil‐in‐water Pickering emulsion is formed using hydrophilic amine‐functionalized silica nanoparticles. Covalent modification using a hydrophobic maleic anhydride copolymer then alters nanoparticle wettability during crosslinking, causing a core‐shell to nanocomposite structural reorganization of the assemblies. The resulting porous nanocomposites maintain discrete microparticle structures and retain payloads in their oil phase even when incubated in competitive solvents such as ethanol.     

Formation and stabilization of Pickering emulsions using salt-sensitive core–shell cationic nanoparticles

Pickering emulsions known for their solid emulsifiers and brilliant stability characters have attracted many researchers’ attention. The controlled stability and demulsification of emulsion are necessary in some cases such as crude oil extraction and drug release. Stimuli-responsive Pickering emulsion could provide suitable controllability and emerged in the last decade. Among various controllable factors, salt ion is known as a critical parameter, but it is rarely investigated. Here, core–shell cationic nanoparticles with a poly-(2-aminoethyl methacrylate hydrochloride) shell and a polystyrene core were used in the preparation of Pickering emulsion. The size and morphology of nanoparticles were monitored by transmission electron microscopy and dynamic light scattering. The microstructure and stability of the formed Pickering emulsion were studied via dynamic light scattering and a polarizing optical microscope under various salt ion types and concentrations. The effect of salt types (Cl^?, ClO₄^?, and PO₄^3?) and salt concentrations on the Pickering emulsion was investigated. Cl^?, ClO₄^?, and PO₄^3? are in situ generated from NaCl, NaClO₄, and (NaPO₃)₆, respectively. It showed that PO₄^3? (100–1000 mM) was unable to form stable Pickering emulsion, while Cl^? and ClO₄^? could induce stable Pickering emulsions under optimized conditions. Furthermore, after increasing the salt concentration over a critical salt concentration, the Pickering emulsion underwent rapid demulsification. This work revealed the effects of salt on size, conformation, charge, wettability, interaction, and adsorption state of nanoparticles and proposed the stability mechanisms of the Pickering emulsion. This opened up more potential applications in the field of controlled demulsification, petroleum recovery, catalyst recovery, and so on triggered by salt ions.

Graphical abstract

Salt could affect the size, conformation, and interaction of core–shell cationic nanoparticles, which then affect the formation mechanism and stability properties of Pickering emulsions from them.

     

Synthesis and characterization of TiO2/poly(methyl methacrylate) nanocomposites via surface thiol-lactam initiated radical polymerization

An approach to the surface modification of TiO2 nanoparticles was described based on the thiol functionalization of TiO2 followed by thiol-lactam initiated radical polymerization (TLIRP) of methyl methacrylate (MMA). FT-IR, XRD and XPS analyses confirmed the grafting of the polymer on the TiO2 surface. TGA analysis revealed superior thermal stability of PMMA-g-TiO2 compared with PMMA. TEM measurements and time-dependent phase monitoring suggested much higher colloidal stability of PMMA-g-TiO2 than TiO2 in toluene. The controlled nature of the TLIRP of MMA from the surface of TiO2 was determined by GPC analysis.     

原位聚合制备P（AN-MMA）/TiO2复合聚合物电解质

以丙烯腈(AN)和甲基丙烯酸甲酯(MMA)为单体,在钛酸丁酯水解生成的TiO2粒子表面乳液聚合制备复合聚合物P(AN-MMA)/TiO2,并以此聚合物制备了多孔复合聚合物膜。采用核磁共振(NMR)、红外光谱(FT-IR)、差热分析(DSC)、扫描电镜(SEM)等对聚合物膜进行了表征,并测试了所得聚合物电解质的交流阻抗谱。结果表明,AN和MMA通过打开各自的C=C双键形成共聚物,TiO2在基体中分散均匀。当TiO2添加量为10.8%时,复合聚合物电解质的室温离子电导率达到1.12×10-3S/cm。     

Effect of surface fluorination of TiO2 particles on photocatalitytic activity of a hybrid multilayer coating obtained by sol-gel method

A multilayer photoactive coating containing surface fluorinated TiO(2) nanoparticles and hybrid matrices by sol gel approach based on renewable chitosan was applied on poly(lactic acid) (PLA) film by a step wise spin-coating method. The upper photoactive layer contains nano-sized functionalized TiO(2) particles dispersed in a siloxane based matrix. For the purpose of improving TiO(2) dispersion at the air interface coating surface, TiO(2) nanoparticles were modified by silane coupling agent 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FTS) with fluoro-organic side chains. An additional hybrid material consisting of chitosan (CS) cross-linked with 3-glycidyloxypropyl trimethoxy silane (GOTMS) was applied as interlayer between the PLA substrate and the upper photoactive coating to increase the adhesion and reciprocal affinity. The multilayer TiO(2)/CS-GOTMS coatings on PLA films showed a thickness of ~4-6 μm and resulted highly transparent. Their structure was exhaustively characterized by SEM, optical microscope, UV-vis spectroscopy and contact angle measurements. The photocatalytic activity of the multilayer coatings were investigated using methyl orange (MeO) as a target pollutant; the results showed that PLA films coated with surface fluorinated particles exhibit higher activity than films with neat particles, because of a better dispersion of TiO(2) particles. The mechanical properties of PLA and films coated with fluorinated particles, irradiated by UV light were also investigated; the results showed that the degradation of PLA substrate was markedly suppressed because of the UV adsorptive action of the multilayer coating.     

不同性能的双亲性纳米TiO2复合粒子改性聚偏氟乙烯超滤膜结构与性能的研究

利用无皂乳液聚合法合成双亲性聚丙烯酸(PAA)-g-聚甲基丙烯酸甲酯(PMMA)-g-硅烷偶联剂KH570-g-纳米TiO2复合体,通过调节亲水链中丙烯酸(AA)与甲基丙烯酸甲酯(MAA)单体的比例控制复合粒子的表面性能.利用红外光谱、接触角测定、扫描电镜(SEM)等表征技术研究不同表面性能的双亲性纳米TiO2复合粒子...