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Jyongsik Jang

Publications and source records attributed to Jyongsik Jang.

At least 19 recordsLinked to original sources
PubMed2007

Controlled amine functionalization on conducting polypyrrole nanotubes as effective transducers for volatile acetic acid.

Pristine (carboxylated) and aminated polypyrrole nanotubes were successfully fabricated using vapor deposition polymerization with a template. In particular, aminated polypyrrole nanotubes were readily synthesized by modifying the nanotube surface with open polyamine chains. Pristine and aminated polymer nanotubes were used as the transducer to acetic acid vapor. Amino-functionalized nanotubes revealed more enhanced sensitivity than the pristine carboxylated nanotubes with the increasing number of amine spacers due to the increased polymer/analyte partition coefficient and mass uptake of the analyte. Moreover, polyamine-functionalized nanotubes presented a reversible and reproducible response to acetic acid up to 40% sensitivity. The aminated polypyrrole nanotubes demonstrated the potential capability to be excellent transducers for volatile fatty acids in disposable sensors.

Acetates↗
PubMed2006

Sensing behaviors of polypyrrole nanotubes prepared in reverse microemulsions: effects of transducer size and transduction mechanism.

Polypyrrole (PPy) nanotubes with different diameters were readily fabricated using cylindrical micelle templates in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse microemulsions. Interestingly, Raman spectroscopy and ultraviolet (UV)-visible spectroscopy revealed that the PPy nanotubes with smaller diameters had a more extended conjugation length as well as a higher oxidation level. The PPy nanotubes were deposited onto a microelectrode array and were exposed to chemical vapor and electromagnetic radiation: typically, NH(3) vapor and UV light were chosen. The electrical response of PPy nanotubes to two different kinds of analytes was strongly dependent on their diameters. Moreover, since the small dimensions of PPy nanotubes facilitated the interaction between nanotubes and analytes, the PPy nanotube sensors showed conspicuously enhanced responses compared with conventional PPy.

Dioctyl Sulfosuccinic Acid↗
PubMed2006

One-step fabrication of silver nanoparticle embedded polymer nanofibers by radical-mediated dispersion polymerization.

Silver nanoparticle embedded poly(vinyl alcohol)-poly(methyl methacrylate) nanofibers, ca. 30 nm in diameter and ca. 60 microm in length, were fabricated by one-step radical-mediated dispersion polymerization using 2,2'-azobis(isobutyronitrile) to reduce the silver ions. In this methodology, PVA acted both as a gelator to form the nanofibers and as a stabilizer to protect the silver clusters from sintering.

Methacrylates↗
PubMed2005

Formation mechanism of conducting polypyrrole nanotubes in reverse micelle systems.

Polypyrrole (PPy) nanotubes were readily fabricated through chemical oxidation polymerization in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse (water-in-oil) emulsions. The reverse cylindrical micelle phase was characterized, and the key factors affecting the formation of PPy nanotubes were systematically inspected. AOT reverse cylindrical micelles were prepared via a cooperative interaction between an aqueous FeCl3 solution and AOT in an apolar solvent. In the H2O/FeCl3/AOT/apolar solvent system, the aqueous FeCl3 solution played a role in increasing the ionic strength and decreasing the second critical micelle concentration of AOT. As a result, AOT reverse cylindrical micelles could be spontaneously formed in an apolar solvent. In addition, iron cations were adsorbed to the anionic AOT headgroups that were capable of extracting metal cations from the aqueous core. Under these conditions, the addition of pyrrole monomer resulted in the chemical oxidation polymerization of the corresponding monomer at the surface of AOT reverse cylindrical micelles, followed by the formation of tubular PPy nanostructures. In a typical composition (74.0 wt % hexane, 22.4 wt % AOT, and 3.6 wt % aqueous FeCl3 solution at 15 degrees C), the average diameter of PPy nanotubes was approximately 94 nm and their length was more than 2 mum. The PPy nanotube dimensions were affected by synthetic variables such as the weight ratio of aqueous FeCl3 solution/AOT, type of apolar solvent, and reaction temperature. Moreover, the relationship between the diameter and the conductivity of the nanotubes was investigated.

Chlorides↗
PubMed2005

Fabrication of mesoporous polymer using soft template method.

Mesoporous polymer materials were fabricated from micelle/polymer precursors prepared by the micelle template method in reverse microemulsion systems and the pore size could be tuned by varying the type and concentration of surfactant.

Journal Article↗
PubMed2004

Morphogenesis of evaporation-induced self-assemblies of polypyrrole nanoparticles dispersed in a liquid medium.

Evaporation-induced self-assemblies (EISAs) with various morphologies were selectively fabricated by drying a solution containing polypyrrole nanoparticles. The morphogenesis of EISAs was strongly dependent upon the solvent evaporation rate and the nanoparticle concentration. In the case of fast evaporation, 2-D dendrites or pseudo 1-D dendrites were observed. When the liquid medium evaporated slowly, ring and spherulitic assemblies took place. Multiple rings could be created on a substrate surface under one single drop.

Models, Chemical↗