Yeon Jae Jung

Monodisperse and fluorescent poly(styrene-co-methacrylic acid-co-2-naphthyl methacrylate)/Fe3O4 composite particles

This article describes the preparation and characterization of fluorescent and magnetic composite particles of poly(styrene-co-methacrylic acid-co-2-naphthyl methacrylate) (poly(St/MAA/NMA)). First, monodisperse (D(w)/D(n)<1.1) and fluorescent poly(St/MAA/NMA) submicron particles were prepared using emulsifier-free emulsion polymerization by varying the concentration of the fluorescent comonomer, i.e., NMA. Composition of the particles was characterized by (1)H NMR, FT-IR, GPC, and DSC analyses. The molecular weights and particle size of the particles were dependent on the NMA concentration. Second, Fe(3)O(4) nanoparticles were immobilized onto the poly(St/MAA/NMA) submicron particles to give rise to multifunctional properties. The morphology and particles size were characterized by FE-SEM and CHDF. These poly(St/MAA/NMA)/Fe(3)O(4) composite particles exhibited both fluorescent properties under UV irradiation at 365 nm and magnetic properties. Photo-luminescent (PL) intensity of the particles showed linear dependence with NMA concentration.

Luminescent gold–poly(thiophene) nanoaggregates prepared by one-step oxidative polymerization

We report the facile synthesis, formation mechanism, and photoluminescent (PL) properties of gold–poly(thiophene) (Au–PTh) nanoaggregates. They were prepared by one-step oxidative polymerization, in which Au3+ ion was utilized as an oxidizing agent for the polymerization of thiophene. Transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM) analyses demonstrated that the ‘raspberry-like’ Au–PTh nanoaggregates consist of individual Au NPs covered by PTh and stabilized by Tween 80. For Au–PTh nanoaggregates, a clear red shift in the SP peak was observed in the UV absorption spectra as compared with pristine Au nanoparticles (NPs). This red shift of the SP band is a consequence of the location of π-conjugated PTh on the surface of Au NPs, resulted from a strong binding between sulfur atoms of PTh and the Au NPs (sulfur–gold interaction). The strong interaction between the gold and sulfur atoms of PTh in the Au–PTh nanoaggregates was observed by X-ray photoelectron spectroscopy (XPS) analysis. The SP effect contributes to the PL intensity enhancement of the Au–PTh nanoaggregates and was confirmed by confocal laser scanning microscopy (CLSM).

Tunable fluorescent poly(styrene-co-methacrylic acid)/Au-Aphen hybrid nanoparticles via surface immobilization

Tunable fluorescent poly(styrene-co-methacrylic acid) [poly(St-co-MAA)]/Au-Aphen hybrid nanoparticles were fabricated by immobilizing the 5-amino-1,10-phenanthroline functionalized gold nanoparticles (Au-Aphen) on the surface of copolymer nanoparticles in aqueous solution. Aphen-Au cationic complex was absorbed on the surface of poly(St-co-MAA) nanoparticles by using electrostatic interactions and metalized by a reduction process. Thus, the functionalized metal nanoparticles can be immobilized onto the surface of the copolymer nanoparticles to significantly modify their optical properties. The structure of the hybrid nanoparticles was confirmed by infrared spectroscopy, scanning electron microscopy, X-ray diffraction, UV-vis spectrophotometery and spectrofluorophotometery studies. These hybrid nanoparticles exhibited fluorescence properties with enhanced photoluminescence quantum yield compared to the gold clusters. Furthermore, the fluorescent emission wavelength of hybrid nanoparticles can be tuned precisely by changing the amount of Aphen functionalized gold nanoparticles on the surface of poly(St-co-MAA) nanoparticles. PL spectra of hybrid nanoparticles showed a red-shift with increasing the amount of functionalized gold on the poly(St-co-MAA) nanoparticles surface in a water medium.