大分子阳离子光引发剂聚苯乙烯-碘鎓六氟锑酸盐的合成及其感光性能的研究

本文用羟基对甲苯磺酰氧基碘苯与聚苯乙烯进行亲电取代反应,得到大分子阳离子碘鎓盐光引发剂聚苯乙烯碘鎓-六氟锑酸盐(PS-I·SbF₆).用核磁共振仪、傅立叶红外光谱仪、凝胶渗透色谱仪、差示扫描量热仪、紫外分光光度仪对其进行了表征.与小分子碘鎓盐系光引发剂相比,PS-I·SbF₆的紫外最大吸收波长λ_max红移,在240-270 nm范围内有较强的吸收;固化成膜后其相对迁移率较小分子光引发剂有显著下降.初步研究了PS-I·SbF₆在环氧体系中的光固化性能,结果表明该体系有较好的光固化和后固化特性.     

Alkaline phosphatase encapsulated in gellan-chitosan hybrid capsules

Alkaline phosphatase (ALP) was encapsulated in gellan-chitosan polyion complex (PIC) capsules using a convenient procedure. The recovery of ALP was about 50% when the capsules were prepared by dropping a solution of ALP and gellan mixture (ALP/gellan) into a chitosan solution. When p-nitrophenyl phosphate (p-NPP) and 5-bromo-4-chloro-3-indolyl phosphate (BCIP) were incubated with ALP/gellan-chitosan capsules as substrates for ALP, the transparent colorless capsules changed to yellow and blue, respectively. The encapsulation of ALP into the PIC capsules was also confirmed by SDS-PAGE and immunoblot analyses. The ALP and polypeptides of more than 30 kDa remained without release even after incubation at 4 degrees C for 14 d. The biochemical properties of the encapsulated ALP activity were similar to those of the intact enzyme. When the solution containing p-NPP was loaded on a column packed with ALP/gellan-chitosan capsules at 27 degrees C, approximately 75% of p-NPP was hydrolyzed by passing through the column. No significant leakage of ALP was observed during the procedure, indicating that the capsules were resistant to pressure in the chromatographic operation. Furthermore, 70% of the hydrolytic activity of the packed capsules remained after storage at 4 degrees C for one month. These results suggest that the polyion complex capsules could be useful materials for protein fixation without chemical modification. [Diagram: see text] Encapsulation of ALP into PIC capsules and the morphological changes seen in the absence of the ALP substrate and in the presence of p-NPP and BICP.     

Fabrication of nanocapsules with Au particles trapped inside carbon and silica nanoporous shells

Carbon capsules with hollow cores and mesoporous shells (HCMS) containing entrapped Au particles were prepared by template replication from solid core/mesoporous shell silica spheres with encapsulated Au particles. The resulting HCMS carbon capsules were then nanocast one step further to generate Au-trapping hollow core silica capsules with nanostructured shells.     

Waterborne Dispersions of a Polymer‐Encapsulated Inorganic Particle Nanocomposite by Phase‐Inversion Emulsification

Inorganic silica nanoparticles were encapsulated with an epoxy resin to give waterborne nanocomposite dispersions, using the phase‐inversion emulsification technique. Sub‐micron‐sized waterborne particles with narrow size distribution were prepared such. Microscopy results indicate that all the silica nanoparticles are encapsulated within the composites and uniformly dispersed therein. Curing of the nanocomposite dispersions proceeded in a controlled manner.     

Silica‐Protected Micron and Sub‐Micron Capsules and Particles for Self‐Healing at the Microscale

A generalized silica coating scheme is used to functionalize and protect sub‐micron and micron size dicyclopentadiene monomer‐filled capsules and polymer‐protected Grubbs' catalyst particles. These capsules and particles are used for self‐healing of microscale damage in an epoxy‐based polymer. The silica layer both protects the capsules and particles, and limits their aggregation when added to an epoxy matrix, enabling the capsules and particles to be dispersed at high concentrations with little loss of reactivity.

     

Molecules at close range: encapsulated solvent molecules in pyrogallol[4]arene hexameric capsules

[reaction: see text] Pyrogallol[4]arenes form hexameric capsules with a large cavity and can be regarded as nanoreactors. The (1)H NMR signals of the encapsulated chloroform and benzene molecules are very complex, which may indicate that these encapsulated molecules are trapped in slightly different capsules. Co-encapsulation was found to be favored, and the ASIS effect was found to be enhanced, probably due to the close proximity and the higher molecular fraction of the benzene/chloroform complex in the capsule.     

Preparation of microcapsules containing a curing agent for epoxy resin by polyaddition reaction with the self-assembly of phase-separated polymer method in an aqueous dispersed system

To prepare cured epoxy resin particles encapsulating a curing agent (diamine), the self-assembly of phase-separated polymer (SaPSeP) method was developed to be applicable to polyaddition reaction of a stoichiometrically imbalanced system. The SaPSeP method was developed by the authors for preparation of micrometer-sized, hollow cross-linked polymer particles by radical polymerization based on the self-assembly of phase-separated polymer at the inner interface of particles. Although a polyaddition reaction, in general, requires that the reactants are in stoichiometric balance for the cure reaction to proceed well, diamine was successfully encapsulated within a cured epoxy resin shell by utilizing the SaPSeP method regardless of stoichiometric imbalance. The results provide further support of the previously proposed SaPSeP mechanism for the formation of hollow particles. Moreover, such diamine capsules can be employed in one-component epoxy adhesives.     

Entrapment of α‐Chymotrypsin into Hollow Polyelectrolyte Microcapsules

Stable hollow polyelectrolyte capsules were produced by the layer‐by‐layer assembling of non‐biodegradable polyelectrolytes – poly(allylamine) and poly(styrenesulfonate) on melamine formaldehyde microcores followed by the core decomposition at low pH. A proteolytic enzyme, α‐chymotrypsin, was encapsulated into these microcapsules with high yields of up to 100%. The encapsulation procedure was based on the protein adsorption onto the capsule shells and on the pH‐dependent opening and closing of capsule wall pores. The protein in the capsules retained a high activity, and thermo‐ and storage stability. The nanostructured polyelectrolyte shell protected the proteinase from a high molecular weight inhibitor. Such enzyme‐loaded capsules can be used as microreactors for biocatalysis.     

Inclusion of 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl in a calixarene nanocapsule in the solid state

We present an X-ray diffraction (XRD) and multi frequency electron spin resonance (ESR) study of the structure and dynamics of an inclusion complex of p-hexanoyl calix[4]arene (C6OH) with 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl (MT). The single crystal XRD experiments reveal that MT along with ethanol (solvent) molecules are entrapped in a capsular type crystalline lattice of the host C6OH material. ESR measurements were performed at 9.2 GHz/0.33 T (X-band) and at 360 GHz/14 T. In order to avoid ESR line broadening resulting from electron dipole-dipole interaction between nitroxides occupying neighbouring capsules in the crystal lattice, the capsules containing nitroxides were separated from each other by capsules containing diamagnetic dibenzylketone (DBK). Due to the extremely high g-tensor resolution of ESR at 360 GHz, we were able to distinguish, by shifts of their g(xx) component, between encapsulated nitroxide molecules forming a hydrogen bond between their O-(N) group and the OH group of an ethanol molecule occupying the same capsule and nitroxides missing this interaction. Temperature dependent ESR measurements revealed an orientational anisotropy in the motion of MT encapsulated in C6OH. Solid lipid nanoparticles (SLN) prepared from C6OH and loaded with the nitroxide retained the microcrystalline capsular structure of the pertinent inclusion complex. We found that encapsulated MT in SLNs becomes inaccessible to reducing agents such as sodium ascorbate.     

Flame‐retardant epoxy resins: An approach from organic–inorganic hybrid nanocomposites

Phosphorus‐containing epoxy‐based epoxy–silica hybrid materials with a nanostructure were obtained from bis(3‐glycidyloxy)phenylphosphine oxide, diaminodiphenylmethane, and tetraethoxysilane in the presence of the catalyst p‐toluenesulfonic acid via an in situ sol–gel process. The silica formed on a nanometer scale in the epoxy resin was characterized with Fourier transform infrared, NMR, and scanning electron microscopy. The glass‐transition temperatures of the hybrid epoxy resins increased with the silica content. The nanometer‐scale silica showed an enhancement effect of improving the flame‐retardant properties of the epoxy resins. The phosphorus–silica synergistic effect on the limited oxygen index (LOI) enhancement was also observed with a high LOI value of 44.5. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 986–996, 2001     

Synthesis and characterization of novel epoxy resins‐filled microcapsules with organic/inorganic hybrid shell for the self‐healing of high performance resins

Novel microcapsules (MCs) with organic/inorganic hybrid shell were successfully fabricated using epoxy resin as core material and nano boron nitride (BN) and mesoporous silica (SBA‐15) as inorganic shell materials in aqueous solution containing a water‐compatible epoxy resin curing agent. The morphologies, thermal properties and Young's moduli of MCs were investigated. The results indicated that epoxy resins were encapsulated by BN/SBA‐15/epoxy polymer hybrid layer, the resulting MCs were spherical in shape and the introduction of inorganic particles made MCs had rough surface morphology. The mean modulus value of MCs was from 2.8 to 3.1 GPa. The initial decomposition temperature (T_di) of MCs at 5 wt% weight loss was from 309 to 312°C. MCs showed excellent thermal stability below 260°C. The structures and properties of MCs could be tailored by controlling the weight ratio of inorganic particle. When the weight ratio of BN to SBA‐15 was 0.15:0.10, MCs had the highest T_di and modulus. The resulting MCs were applied to high performance 4,4′‐bismaleimidodiphenylmethane/O,O′‐diallylbisphenol A (BMI/DBA) system to design high performance BMI/DBA/MC systems. Appropriate content of MCs could improve the fracture toughness and maintain the glass transition temperature (T_g) of BMI/DBA system. The core materials released from fractured MCs could bond the fracture surfaces of the BMI/DBA matrix through the polymerization of epoxy resins. When the healing temperature schedule of 100°C/2h+150°C/1h was applied, 15 wt% MCs recovered 98% of the virgin fracture toughness of BMI/DBA. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation, structure, and imaging of luminescent SiO2 nanoparticles by covalently grafting surfactant-encapsulated europium-substituted polyoxometalates

A novel route to the preparation of luminescent silica nanoparticles and coloration for living cells was demonstrated in this article. A europium-substituted polyoxometalate was encapsulated by a hydroxyl-group-terminated double-chain quaternary ammonium cation through an ion replacement process, yielding an organic-inorganic complex with core-shell structure bearing hydroxyl groups located at the periphery. The introduction of -OH groups not only increased the solubility of the complex in polar solvents but also caused it to embed into the inner matrix of silica nanoparticles covalently and be well-dispersed through an in situ sol-gel reaction with tetraethyl orthosilicate. Elemental analysis and spectral characterization confirmed the formation of prepared complexes with the anticipated chemical composition. Scanning and transmission electron microscopy images illustrated the size change of luminescent nanoparticles with smooth surfaces and well-dispersed polyoxometalate complexes inside of the silica matrix. X-ray photonic spectra and ζ-potential measurements revealed the chemical association between the silica matrix and the complex. Luminescent spectral characterization indicated the well-retained photophysical property of Eu-substituted polyoxometalate in silica nanoparticles. The surface amino-modified silica nanoparticles were applied to cell coloration, and the dyed Hela cells were observed through laser confocal fluorescence microscopy.     

Dynamics of a supramolecular capsule assembly with pyrene

Water-soluble octaacid cavitands (OAs) form dimeric capsules suitable for guest incorporation. Our studies reveal that the mechanism of pyrene (Py) binding involves the rapid (<1 ms) formation of the Py·OA complex followed by slower binding with the second OA. The dissociation of the capsular OA·Py·OA complex occurs with a lifetime of 2.7 s, which is 5 orders of magnitude slower than the microsecond opening/closing ("breathing") previously observed to provide access of small molecules to the encapsulated guest. These different dynamics of the capsules have a potential impact on how the chemistry of included guests could be altered.     

Ultrasonically induced opening of polyelectrolyte microcontainers

The effect of ultrasonic treatments of different intensity and duration on the integrity and permeability of polyelectrolyte capsules was investigated both in poly(allylamine)/poly(styrene sulfonate) and Fe(3)O(4)/poly(allylamine)/poly(styrene sulfonate) polyelectrolyte capsules. Ultrasonic treatment of polyelectrolyte capsules induces the destruction of the polyelectrolyte shell and the release of the encapsulated material even at short (5 s) sonification times. The presence of magnetite nanoparticles significantly improves the efficiency of the ultrasonically stimulated release of the encapsulated compounds and enables magnetically controlled delivery to the desired site before ultrasonic treatment. Release of the encapsulated compound induced at ultrasonic power comparable to those of ultrasonic generators applied in medicine, demonstrating practical application of the ultrasonically triggered capsule opening in medicine.     

AFM substantiation of the fracture behavior and mechanical properties of sol–gel derived silica packed epoxy networks

Silica packed epoxy networks are prepared in two steps via in situ, solvent free sol–gel processing of tetraethoxysilane in liquid epoxy monomer and curing the mixture with a flexible diamine afterwards. The influence of filler content and processing conditions on the mechanical properties and the fracture behavior is studied by means of the static mechanical analysis and AFM characterization of the pristine and the fractured polymer surfaces, and a mechanism to enhance polymer strength and toughness is proposed. The in–situ evolution and packing of silica nanostructures into epoxy networks influences the overall morphology and performance of polymers under high stress. It is found that smaller silica domains distributed at the molecular level cause efficient crack distribution by absorbing energy and thus improve the strength and toughness of silica packed epoxy polymers.     

An iron Schiff base complex loaded mesoporous silica nanoreactor as a catalyst for the synthesis of pyrazine-based heterocycles

An iron Schiff base complex was encapsulated in SBA-15 mesoporous silica to afford a Fe(III)-Schiff base/SBA-15 heterogeneous nanocatalyst for the synthesis of pyridopyrazine and quinoxaline heterocycles. These reactions proceeded in water with excellent yields. The catalyst was characterized by physico-chemical and spectroscopic methods and found to retain the characteristic channel structures of the SBA-15, allowing good accessibility of the encapsulated metal complex.     

Microgel Capsules Tailored by Droplet‐Based Microfluidics

Microgel capsules are micrometer‐sized particles that consist of a cross‐linked, solvent‐swollen polymer network complexed with additives. These particles have various applications, such as drug delivery, catalysis, and analytics. To optimize the performance of microgel capsules, it is crucial to control their size, shape, and content of encapsulated additives with high precision. There are two classes of microgel‐capsule structures. One class comprises bulk microcapsules that consist of a polymer network spanning the entire particle and entrapping the additive within its meshes. The other class comprises core–shell structures; in this case, the microgel polymer network just forms the shell of the particles, whereas their interior is hollow and hosts the encapsulated payload. Both types of structures can be produced with exquisite control by droplet‐based microfluidic templating followed by subsequent droplet gelation. This article highlights some early and recent achievements in the use of this technique to tailor soft microgel capsules; it also discusses applications of these particles. A special focus is on the encapsulation of living cells, which are very sensitive and complex but also very useful additives for immobilization within microgel particles.     

外围为柔性链状取代基团Ni-酞菁配合物的合成及其在MCM-41中的装载

合成了外围具有柔性链状基团的2（3）,9（10）,16（17）,23（24）-四-（N,N-二乙胺基乙氧基）Ni-酞菁配合物（2）．以正硅酸乙酯为硅源,十六烷基三甲基溴化铵为模板剂,水热法将该Ni-酞菁配合物（2）装载到MCM-41中．利用UV-Vis-NIR,FT-IR,XRD,TEM,FESEM及N2吸附-脱附等温线对制备的样品进行了表征．研究表明制备的样品中Ni-酞菁配合物（2）主要以单体和二聚体的形式存在于MCM-41中．通过不同制备酞菁浓度的装载研究表明,较高制备酞菁浓度有利于制备结晶度及孔道有序性较高的介孔分子筛样品．     

Acoustic emission study of the TDCB test of microcapsules filled self-healing polymer

The failure process of self-healing microcapsule filled epoxy composites was investigated with Acoustic Emission (AE) measurement during tapered double cantilever beam (TDCB) tests. Unfilled, epoxy microcapsule filled and self-healing microcapsule (dual-microcapsules consisting of epoxy capsules and trifluoromethanesulfonic acid (TfOH) capsules) filled epoxy matrix specimens were compared. It was found that, with acoustic emission measurements, reliable data can be retrieved about the nature and progress of crack propagation and failure. Comparing the unfilled and the microcapsule filled specimens, considerably more AE hits were detected in the latter case due to the cracking of capsules and capsule-matrix debonding, which was confirmed by scanning electron microscopy investigations. Also, key differences were observed in the shape of the sum of AE hits curves and amplitude ranges of detected AE hits. Uniform distribution of the healing agent was demonstrated by energy-dispersive X-ray spectroscopy.     

Thermomechanical properties and phase structure of epoxy/silica nano‐hybrid materials constructed from a linear silicone oligomer

Epoxy‐grafted silicone oligomer (ESO), which has a linear silicone chain in the backbone moiety, was synthesized from a trifunctional alkoxysilane via a sol–gel reaction. Characterization of ESO was performed with ¹H and ²⁹Si NMR, Fourier transform infrared, and gel permeation chromatography. The number‐average molecular weight of ESO was 3300. By adding the silicone oligomer as the inorganic source in the curing process of the epoxy resin, novel epoxy/silica hybrid materials were prepared. It was observed by transmission electron microscope that fine silica‐rich domains of about 5‐nm diameter were uniformly dispersed in the cured epoxy matrix. Thermomechanical properties of the hybrid materials were also investigated. The storage modulus in the rubbery region and the peak area of the tan δ curve at the glass‐transition region increased and decreased, respectively, with the hybridization of the silica network. The mobility of the epoxy network chains should be considerably suppressed by the hybridization with the silica network. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1631–1639, 2005