Fabrication of mesoporous polymer using soft template method

Mesoporous polymer materials were fabricated from micelle/ polymer precursors prepared by the micelle template method in reversemicroemulsion systems and the pore size could be tuned by varying the type and concentration of surfactant.This work was supported by the Brain Korea 21 program of the Korea Ministry of Education and Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center

Fabrication of Carbon Microcapsules Containing Silicon Nanoparticles-Carbon Nanotubes Nanocomposite for Anode in Lithium Ion Battery

Carbon microcapsules containing silicon nanoparticles (Si NPs)-carbon nanotubes (CNTs) nanocomposite (Si-CNT@C) have been fabricated by a two step polymerization method. Silicon nanoparticles-carbon nanotubes (Si-CNT) nanohybrids were prepared with a wet-type beadsmill method. A polymer, which is easily removable by a thermal treatment (intermediate polymer) was polymerized on the outer surfaces of Si-CNT nanocomposites. Subsequently, another polymer, which can be carbonized by thermal heating (carbon precursor polymer) was incorporated onto the surfaces of pre-existing polymer layer. In this way, polymer precursor spheres containing Si-CNT nanohybrids were produced using a two step polymerization. The intermediate polymer must disappear during carbonization resulting in the formation of an internal free space. The carbon precursor polymer should transform to carbon shell to encapsulate remaining Si-CNT nanocomposites. Therefore, hollow carbon microcapsules containing Si-CNT nanocomposites could be obtained (Si-CNT@C). The successful fabrication was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). These final materials were employed for anode performance improvement in lithium ion battery. The cyclic performances of these Si-CNT@C microcapsules were measured with a lithium battery half cell tests.close

Fabrication of mesoporous polymer/silica hybrid using surfactant-mediated sol–gel method

A mesoporous polymer/silica hybrid was fabricated by a surfactant-mediated sol–gel method. Under our experimental conditions, acrylonitrile (AN) monomer was located at the exterior of micelles and the sol–gel reaction of tetraethoxyorthosilicate (TEOS) proceeded concurrently with the polymerization reaction of the AN monomer. In other words, the micelle/polyacrylonitrile/silica precursor was synthesized through the radical polymerization accompanied with a hydrolysis/condensation single reaction in a reaction system. This is a unique characteristic of our methodology, which embraces the concept of micelle templating. The pore diameter of the mesoporous polymer/silica hybrid could be tuned by varying the spacer length and concentration of surfactants. Furthermore, compared with conventional mesoporous carbons, the carbonized mesoporous polymer/silica hybrids displayed an enhanced electrical performance favorable for use as a supercapacitor.This work has been supported by Brain-Korea 21 program of the Korean Ministry of Education and the Korean Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center in Seoul National University

Carbon nanofiber/polypyrrole nanocable as toxic gas sensor

Carbon nanofiber (CNF)/polypyrrole (PPy) coaxial nanocables were successfully fabricated via one-step vapor deposition polymerization (VDP), and their capability to perceive irritant gases such as ammonia (NH3) and hydrochloric acid (HCl) was systematically examined. The Fourier transform infrared (FT-IR) spectra confirmed the formation of a PPy layer on the CNF surface. In addition, a transmission electron microscopy (TEM) image represented the formation of an ultrathin and uniform PPy layer onto the surface of CNF. The thickness of the PPy layer was conveniently controlled by varying the feeding amount of the corresponding monomer. The PPy-coated CNF exhibited an enhanced response signal due to the presence of the thin and uniform conducting polymer layer, and their response was strongly dependent on the thickness of the PPy layer.This work was supported by the Brain-Korea 21 Program of the Korea Ministry of Education and Korea Science and Engineering Foundation through Hyperstructured Organic Materials Research Center in Seoul National University

Selective Fabrication of Polymer Nanocapsules and Nanotubes Using Cyclodextrin as a Nanoporogen

Polyacrylonitrile (PAN) nanocapsules and nanotubes were selectively synthesized by microemulsion polymerisation using b-cyclodextrin (b-CD) as a nanoporogen. Iron(III) chloride (FeCl3) was used as a structure-directing agent to fabricate polymer nanotubes. In addition, the average pore size of the PAN nanocapsules and nanotubes could be controlled with the concentration of b-CD

Selective Fabrication of Poly(3,4-ethylenedioxythiophene) Nanocapsules and Mesocellular Foams Using Surfactant-Mediated Interfacial Polymerization

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanocapsules and mesocellular foams have been selectively fabricated by surfactant-mediated interfacial polymerization (see Figure). The morphology of the PEDOT nanomaterials significantly depends on the surfactant concentration, and the PEDOT nanocapsules and mesocellular foams show good performance as supercapacitors.This work was supported by the Brain-Korea 21 Program of the Korea Ministry of Education and the Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center at Seoul National Universit

Polyacrylonitrile Nanofibers: Formation Mechanism and Applications as a Photoluminescent Material and Carbon-Nanofiber Precursor

The facile synthesis of polyacrylonitrile (PAN) nanofibers is achieved using a microemulsion polymerization. The detailed formation mechanism of polymer nanofibers is examined using electron microscopy and UV-vis and Fourier transform infrared spectroscopies, and the optoelectronic properties are studied by confocal laser scanning microscopy. The effects of surfactant properties, such as concentration, chain length, and ionic character, as well as monomer structure and polymerization temperature, on the structure of the resulting polymer nanofibers are also investigated extensively. Importantly, PAN nanofibers exhibited novel photoluminescence (PL), which is observed for the first time. The PL of PAN nanofibers is significantly different from that of PAN nanoparticles. The PAN nanofibers are also used as a precursor for carbon nanofibers. The carbonization temperature has a dominant effect on the degree of crystallinity of the resulting carbon nanofibers. This study is the first demonstration of the fabrication of polymer and carbon nanofibers using a convenient polymerization technique.This work was financially supported by the Brain Korea 21 program of the Korean Ministry of Education and Korea Science and Engineering Foundation through the Hyperstructured Organic Materials Research Center in Seoul National University

Controlled specific placement of nanoparticles into microdomains of block copolymer thin films

Conceptually attractive hybrid materials composed of nanoparticles and elegant block copolymers have become important for diverse applications. In this work, controlled specific placement of nanoparticles such as gold (Au) and titania (TiO2) into microphase separated domains in poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films was demonstrated. The effect of nanoparticle surface functionality on the spatial location of particles inside polymer film was observed by transmission electron microscopy. It was revealed that the location of nanoparticles was highly dependent on the surface ligand property of nanoparticle. In addition, the microphase separation behavior of thin block copolymer film was also affected by the nanoparticle surface functional groups. This study might provide a way to understand the properties and behaviors of numerous block copolymer/nanoparticle hybrid systems.close0

Synthesis and characterization of polyaniline nanorods as curing agent and nanofiller for epoxy matrix composite

Novel PANI nanorods with average diameter of 21–53 nm and length of 0.5–1 mm were synthesized by dispersion polymerization method. The morphology of obtained PANI nanorods was significantly dependent on the type of salt, stirring, and polymerization temperature. Dispersion polymerization with FeCl3 produced longer nanorods than ammonium persulfate (APS) and magnetic stirring decreased the length of nanorods. While the average diameter of PANI nanorods decreased with increasing reaction temperature, the electrical conductivity dropped considerable at high polymerization temperature due to the increment of insulating emeraldine base. Dynamic differential scanning calorimetry (DSC) study showed that the heat of cure was independent of heating rate. On the contrary, the heat of cure was proportional to the content of PANI nanorods as a role of curing agent. Isothermal DSC study revealed that the cure behavior of LCE/PANI nanorod system was an auto-catalyzed reaction. Thermogravimetric analysis (TGA) indicated that the thermal stability of cured LCE/PANI nanocomposite was significantly dependent on the PANI nanorod composition. In addition, the electrical conductivity of LCE/PANI nanocomposite materials was higher than that of conventional epoxy composites. Therefore, PANI nanorods played a role of curing agent owing to the existent amine group and acted as reinforcing filler for cured LCE nanocomposites.This work was financially supported by the Brain-Korea 21 Program of the Korea Ministry of Education and Hyperstructured Organic Materials Research Center supported by Korea Science and Engineering Foundation