Movable Cores Research Articles

Facile approach for temperature-responsive polymeric nanocapsules with movable magnetic cores

A novel facile approach was developed to prepare the well-defined temperature-responsive polymeric nanocapsules with movable magnetic cores (TPNMCs) based on the organic/inorganic sandwich-structured composite nanoparticles with temperature-responsive crosslinked shells via the one-pot approach surface-initiated atom transfer radical copolymerization (SI-ATRP) of N-isopropyl acrylamide (NIPAM) and N,N′-methylenebisacrylamide (MBA) from the surfaces of the Fe 3O 4@SiO 2 core-shell nanoparticles, followed by the selective removal of the silica layer. Based on the temperature-induced volume phase transition and impressive magnetic response, the TPNMCs are expected to be used for the targeted controlled release of sensitive molecules, such as enzymes, proteins or DNA, by responding to the changing the environmental temperature.

Synthesis and characterization of Ag@PPy yolk–shell nanocomposite

Ag@SiO 2@polypyrrole (PPy) nanocomposites were fabricated by a simple method. Ag@PPy yolk–shell nanocomposite was obtained after the removal of the midlayer SiO 2. TEM confirmed that the movable Ag cores were encapsulated in the interior of the hollow PPy nanoparticles. The structure of the resultant product was characterized by the Raman spectrum and X-ray diffraction technologies. Thermogravimetric analysis (TGA) revealed that the thermal stability of the nanocomposites was improved as compared with the pure PPy.

Reparation of silica/poly(methacrylic acid)/poly(divinylbenzene-co-methacrylic acid) tri-layer microspheres and the corresponding hollow polymer microspheres with movable silica core

Hollow poly(divinylbenzene-co-methacrylic acid) (P(DVB-co-MAA)) microspheres were prepared by the selective dissolution of the non-crosslinked poly(methacrylic acid) (PMAA) mid-layer in ethanol from the corresponding silica/PMAA/P(DVB-co-MAA) tri-layer hybrid microspheres, which were afforded by a three-stage reaction. Silica/PMAA core-shell hybrid microspheres were prepared by the second-stage distillation polymerization of methacrylic acid (MAA) via the capture of the oligomers and monomers with the aid of the vinyl groups on the surface of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified silica core, which was prepared by the Stöber hydrolysis as the first stage reaction. The tri-layer hybrid microspheres were synthesized by the third-stage distillation precipitation copolymerization of functional MAA monomer and divinylbenzene (DVB) crosslinker in presence of silica/PMAA particles as seeds, in which the efficient hydrogen-bonding interaction between the carboxylic acid groups played as a driving force for the construction of monodisperse hybrid microspheres with tri-layer structure. The morphology and the structure of silica core, silica/PMAA core-shell particles, the tri-layer hybrid microspheres and the corresponding hollow polymer microspheres with movable silica cores were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS).

Monodisperse Yolk–Shell Nanoparticles with a Hierarchical Porous Structure for Delivery Vehicles and Nanoreactors

A good egg: A general and facile template strategy is presented for the fabrication of yolk–shell structures (see picture) with various types of movable cores, such as gold, SiO2, and magnetic Fe3O4. The vesicle template, formed of a fluorocarbon surfactant, is built up around the core. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Synthesis of hollow fluorescent polymeric microspheres with movable magnetic cores

AbstractLow‐dispersity hollow poly[(ethyleneglycol dimethacrylate)‐co‐(N‐vinylcarbazole)] (P(EGDMA‐co‐NVCz)) fluorescent microspheres with movable magnetic cores were prepared by quantitative removal of the silica component in hydrofluoric acid aqueous solution from the corresponding magnetite/silica/P(EGDMA‐co‐NVCz) tri‐layer hybrid microspheres. The tri‐layer microspheres with magnetic cores and fluorescent polymer shells were synthesized by distillation precipitation copolymerization of ethyleneglycol dimethacrylate crosslinker and N‐vinylcarbazole fluorescent monomer in acetonitrile in the presence of 3‐(methacryloxy)propyltrimethoxysilane‐modified magnetite/silica particles as seeds, which were afforded by a modified Stöber sol–gel process, to coat the magnetite cores. The corresponding hollow fluorescent polymer microspheres with movable magnetic cores were studied using transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, UV‐visible spectroscopy and fluorescence spectroscopy. Copyright © 2010 Society of Chemical Industry

Synthesis of tetra-layer polymer composite microspheres and the corresponding hollow polymer microspheres with Au nanoparticles functionalized movable cores

Hollow poly(ethyleneglycol dimethacrylate) (PEGDMA) microspheres with Au nanoparticle functionalized movable cores were prepared by selective removal of the sandwiched silica mid-layer from the corresponding poly(ethyleneglycol dimethacrylate-co-methacrylic acid)/poly(ethyleneglycol dimethacrylate-co-vinylpyridine)@gold/silica/PEGDMA (P(EGDMA-co-MAA)/P(EGDMA-co-VPy)@Au/SiO2/PEGDMA) tetra-layer composite microspheres, in which the Au nanoparticles were stabilized by the pyridyl groups on the surface and gel-layer of P(EGDMA-co-MAA)/P(EGDMA-co-VPy) particles during the reduction of HAuCl4 with sodium borohydride. The tetra-layer polymer composite microspheres were synthesized via the combination of distillation precipitation polymerization for the preparation of the polymer core and outer shell layer together with the modified Stober sol–gel process for the formation of the sandwiched silica mid-layer. The primary results indicated that the Au nanoparticle functionalized movable cores enabled the hollow polymer microspheres to act as efficient catalysts for the reduction of 4-nitrophenol to 4-aminophenol with sodium borohydride as the reductant.

Synthesis of pH-sensitive hollow polymer microspheres with movable magnetic core

The pH-sensitive hollow poly( N, N′-methylenebisacrylamide- co-methacrylic acid) (P(MBAAm- co-MAA)) microspheres with movable magnetic/silica (Fe 3O 4/SiO 2) cores were prepared by the selective removal of poly(methacrylic acid) (PMAA) layer in ethanol/water from the corresponding Fe 3O 4/SiO 2/PMAA/P(MBAAm- co-MAA) tetra-layer microspheres, which were synthesized by the distillation precipitation copolymerization of N, N′-methylenebisacrylamide (MBAAm) and methacrylic acid (MAA) in the presence of Fe 3O 4/SiO 2/PMAA tri-layer microspheres as seeds in acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The Fe 3O 4/SiO 2/PMAA tri-layer microspheres were afforded by the distillation precipitation polymerization of MAA with 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified Fe 3O 4/SiO 2 core–shell particles as the seeds. The functional multi-layer inorganic/polymer microspheres and the corresponding hollow polymer microspheres with movable magnetic cores were characterized with transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectra, dynamic light scattering (DLS), and vibrating sample magnetometer (VSM).

Preparation of polymer/silica/polymer tri-layer hybrid materials and the corresponding hollow polymer microspheres with movable cores

Tri-layer poly(methacrylic acid-co-ethyleneglycol dimethacrylate)/silica/poly(ethyleneglycol dimethacrylate) (P(MAA-co-EGDMA)/SiO2/PEGDMA) and P(MAA-co-EGDMA)/SiO2/polydivinylbenzene hybrid microspheres were prepared by distillation precipitation polymerization of ethyleneglycol dimethacrylate (EGDMA) and divinylbenzene (DVB) in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified P(MAA-co-EGDMA)/SiO2 microspheres as the seeds. The polymerization of EGDMA and DVB was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat the MPS-modified P(MAA-co-EGDMA)/SiO2 seeds through the capture of EGDMA and DVB oligomer radicals with the aid of vinyl groups on the surface of modified seeds in the absence of any stabilizer or surfactant. Monodisperse P(MAA-co-EGDMA)/SiO2 core–shell microspheres were synthesized by coating of a layer of silica onto P(MAA-co-EGDMA) microspheres via a sol–gel process, which were further grafted by MPS incorporating the reactive vinyl groups onto the surface to be used as the seeds for the construction of hybrid microspheres with tri-layer structure. Hollow poly(ethyleneglycol dimethacrylate) (PEGDMA) and poly(divinylbenzene) (PDVB) microspheres with movable P(MAA-co-EGDMA) core were subsequently developed after the selective etching of the silica mid-layer from the tri-layer hybrid microspheres in hydrofluoric acid. The morphology and structure of the tri-layer polymer hybrids and the corresponding hollow polymer microspheres with movable P(MAA-co-EGDMA) core were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra and X-ray photoelectron spectroscopy (XPS).

Synthesis of Ellipsoidal Hematite/Silica/Polymer Hybrid Materials and the Corresponding Hollow Polymer Ellipsoids

Ellipsoidal trilayer hematite/silica/poly(divinylbenzene) hybrid particles were prepared by distillation precipitation polymerization of divinyl benzene (DVB) in the presence of hematite/3-(methacryloxy)propyl trimethoxysilane (MPS)-modified silica (SiO(2)) core-shell particles as the seeds. The polymerization of DVB was performed in neat acetonitrile with 2,2'-azobisisobtyronitrile (AIBN) as initiator to coat the hematite/MPS-modified SiO(2) seeds through the capture of DVB oligomer radicals with the aid of a vinyl group on the surface of the hematite/MPS-modified silica core-shell particles in the absence of any stabilizer or surfactant. The other hematite/silica/polymer trilayer hybrid particles with different polarity and various functionality, such as hematite/silica/poly(ethylene glycol dimethacrylate) and hematite/silica/poly(divinyl benzene- co-methacrylic acid) could also be prepared by this procedure. Hematite/silica/poly( N, N'-methylenebisacrylamide) composite particles could be prepared with unmodified hematite/silica particles as seeds. Hollow poly(divinyl benzene) (PDVB) and poly( N, N'-methylenebisacrylamide) (PMBAAm) ellipsoids with movable hematite cores were subsequently developed after the selective etching of the silica midlayer in diluted hydrofluoric acid from hematite/silica/PDVB and hematite/silica/PMBAAm trilayer hybrids. Hollow PDVB ellipsoids were obtained by removal of the silica midlayer and hematite core of the trilayer hybrids with concentrated HF solution. The resultant trilayer hybrid particles and hollow polymer ellipsoids were characterized by transmission electron microscopy and vibrating sample magnetometer.

Synthesis of a Au/Silica/Polymer Trilayer Composite and the Corresponding Hollow Polymer Microsphere with a Movable Au Core

Gold/silica/poly(N,N'-methylenebisacrylamide) (Au/SiO2/polyMBAAm) trilayer composite materials were prepared by distillation precipitation polymerization of N,N'-methylenebisacrylamide (MBAAm) in the presence of Au/SiO2 particles as seeds, in which the seeds were prepared by a combination of gold-complexing and silane coupling agent with a further modified Stöber method. The polymerization of MBAAm was performed in neat acetonitrile with 2,2'-azobisisobutyronitrile as an initiator to encapsulate the Au/SiO2 seeds driven by the hydrogen-bonding interaction between the hydroxyl group on the surface of the seeds and the amide unit of polyMBAAm without modification of the Au/SiO2 surface in the absence of any stabilizer or surfactant. Hollow polyMBAAm microspheres with movable Au cores were further developed by the selective removal of the middle silica layer with hydrofluoric acid. The resultant trilayer Au/SiO2/polyMBAAm composite and hollow polyMBAAm microspheres with movable Au cores were characterized by transmission electron microscopy. The diffusion of chemicals across the polyMBAAm shell was investigated by a catalytic reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride as a reductant.

Facile Synthesis of Hollow Polymer Microspheres with Movable Cores with the Aid of Hydrogen-Bonding Interaction

Poly(divinylbenzene-co-acrylic acid) (poly(DVB-co-AA)) hollow microspheres with movable poly(DVB-co-AA) cores were prepared by a facile route. In this approach, poly(DVB-co-AA) microspheres were first used as templates to synthesize poly(DVB-co-AA)@PAA core-shell particles with a non-crosslinked PAA shell by distillation precipitation polymerization in acetonitrile. In situ polymerization to prepare poly(DVB-co-AA)@PAA@poly(DVB-co-AA) trilayer microspheres was then developed, in which the hydrogen-bonding interaction between the carboxylic acid groups played a key role as the driving force for the formation of monodisperse trilayer structure polymer microspheres. After removal of the non-crosslinked poly(acrylic acid) (PAA) midlayer of the poly(DVB-co-AA)@PAA@poly(DVB-co-AA) microspheres in ethanol under basic conditions, poly(DVB-co-AA) hollow microspheres with movable poly(DVB-co-AA) cores were obtained. Functional poly(DVB-co-AA) cores could be released successfully when the hollow structure was destroyed. The resultant core-shell, trilayer polymer microspheres and hollow polymer microspheres with movable cores were characterized by transmission electron microscopy (TEM), dynamic laser scattering (DLS), and Fourier transform infrared (FT-IR) spectra.

Double‐Walled SnO2 Nano‐Cocoons with Movable Magnetic Cores

Double‐Walled SnO₂ Nano‐Cocoons with Movable Magnetic Cores

Active type vibration isolating support system

An active type vibration isolating support system includes: an elastic body for elastically supporting a vibratory body; a liquid chamber to be defined by the elastic body; a movable member for changing capacity of the liquid chamber; and an actuator for driving the movable member. The actuator has: a fixed core; a movable core coupled to the movable member for being arranged opposite to the fixed core via an air gap; and a coil for generating an electromagnetic attracting force between the fixed and movable cores. The movable member and the movable core are coupled together through coupling units capable of adjusting the air gap. Thus, without preparing several types of coupling members, it is possible to obtain a desired vibration isolating characteristic by freely adjusting the air gap between the fixed core and the movable core.

Synthesis and Characterization of Monodispersed Core−Shell Spherical Colloids with Movable Cores

Gold nanoparticles have been conformally coated with amorphous silica (using a sol-gel method) and then an organic polymer (via surface-grafted, atom transfer radical polymerization) to form spherical colloids with a core-double-shell structure. The thickness of silica and polymer shells could be conveniently controlled in the range of tens to several hundred nanometers by changing the concentration of the reagent and/or the reaction time. Selective removal of the silica layer (through etching in aqueous HF) led to the formation of hollow polymer beads containing movable gold cores. This new form of core-shell particles provides a unique system for measuring the feature size and transport property associated with hollow particles. In one demonstration, we showed that the thickness of a closed polymer shell could be obtained by mapping the electrons backscattered from the core and shell. In another demonstration, the plasmon resonance band of the gold cores was used as an optical probe to follow the diffusion kinetics of chemical reagents across the polymer shells.

A new high sensitivity magnetic system for microposition measurement

This article presents a new design of a magnetic system which can be used as a position sensing system for precision measurements. The proposed system consists of driving coils, position-detecting coils, movable cores, and magnetic blocks. The cores are put into the position-detecting coils to draw the flux. As the cores move in a motion proportional to the input position, induced voltages arise in the position-detecting coils. The turns ratio and the air-gap dimensions between the magnetic blocks and the movable cores are selected in such a way as to have high sensitivity. To decrease the flux loss and produce the strong flux density, a symmetric and closed loop form is adopted. The elements that affect the system characteristics and sensitivity are turns ratio, air-gap dimension, capacitance effect, excitation frequency, and so forth. The sensitivity of the newly designed system is greater than 2000 mV/(V mm) and the linearity error is below ±0.10% in the range of ±200 μm. The repeatability standard deviation in this system is below 50 nm.