Chong-Bok Yoon

Synthesis and Third-Order Nonlinearity of Dye-Containing Poly(1,4-phenylenevinylene) Derivative

Abstract Newpoly(1,4-phenylenevinylene) (PPV) derivative containing Disperse Red 1 (PBDR1PV) was prepared through organic-soluble precursor route. This polymer was characterized by conventional spectroscopic methods (UV-visible, IR, NMR) and the third-order nonlinear optical coefficient was determined by using third harmonic generation (THG) technique. The measured χ (3) value is about 2.5 × 10 −12 esu.

Synthesis and second-harmonic generation study of DCM-containing polyurethane

Abstract Dicyanomethylene-2-methyl-5-(4-dialkylaminostyryl)-4H-pyran (DCM) moiety was incorporated into the rigid polyurethane to give strong NLO activity and thermal stability. The DCM-containing dihydroxy monomer was prepared with conventional Knoevenagel condition and reacted with 4,4-methylenebis(phenyl isocyanate) to form a functionalized polyurethane. The successful polymerization reaction was identified with several methods such as NMR, FT-IR, UV–VIS absorption spectroscopies. The resulting polymer was soluble in polar solvent such as DMF, DMAc and thin films could be obtained by spin-casting of its solution. From these, we investigated the second-order NLO properties of polymer films by using second-harmonic generation method.

Synthesis and characterization of sulfur-containing PPV derivatives

Abstract New sulfur-containing poly(2-hexylthio-5-methoxy-1,4-phenylenevinylene) (PMHPV) and poly(2-hexylsulfinyl-5-methoxy-1,4-phenylenevinylene) (PMHOPV) were synthesized through water-soluble precursor route. These polymers were characterized using UV-visible, FT-IR and thermal analyses. The light emitting devices composed with ITO/polymer films/A1 were fabricated and luminescent properties were characterized. The PMHOPV that contains the electron-accepting hexylsulfinyl group showed lower electrical conductivity of 1.2 × 10 −4 S/cm than that of PMHPV (9 × 10 −2 S/cm) and maximum EL emission in the longer wavelength region.

Synthesis, electroconductivity and third-order nonlinear optical property of poly(2-isopropoxy-5-methoxy-1,4-phenylenevinylene)

SummaryAsymmetrically disubstituted poly(2-isopropoxy-5-methoxy-1,4-phenylene-vinylene), PIMPV, was prepared in thin films via organic-soluble precursor polymer method. These polymer films could be easily stretched up to 7 times, and the drawn films of the PIMPV could be doped with FeCl3 and I2 to give conductivities of 26.9 and 11.3 Scm-1, respectively. The third-order nonlinear optical susceptibility of the polymer was determined using third harmonic generation(THG) method at 1907 nm, fundamental wavelength. Measured χ(30) (-3α: α, α, α) value was 3.7x10-12 esu.

New second‐order nonlinear optical (NLO) epoxy polymer treated by sol‐gel processing

We have demonstrated a novel approach to achieve a stable second-order NLO polymer by incorporating NLO moieties into a processable epoxy polymer and hardening with crosslinkable sol-gel technique. The crosslinked polymer showed high nonlinearity (d 33 = 41 pm/V) and better thermal stability compared to the prepolymer, which maintained its nonlinearity up to 100°C without significant loss of NLO activity.

Facile Synthesis of New Polyimides Containing Hemicyanine Dye as a Nonlinear Optical Chromophore

Abstract New polyimide derivatives containing hemicyanine dye were synthesized by mild Mitsunobu pathway. High χ(2) value of 100pm/V was obtained, which was higher value than those of other NLO-functionalized polyimides.

New light emitting poly(1,4-phenylenevinylene) derivative containing trifluoromethylstilbene group in the side chain

Abstract New poly(1,4-phenylenevinylene) derivative (PCF3PV) containing electron-accepting trifluoromethylstilbene moiety as a side group was prepared through the organic-soluble precursor pathway. The synthesized PCF3PV was characterized with UV–Visible, FT-IR, thermal analyses as well as photoluminescence and electroluminescence spectroscopies. The luminescent maximum lies at around 548 nm, which is similar to that of dialkoxy-substituted PPV derivatives. Though PCF3PV has two lumophores, stilbene and conjugated PPV backbone in main and side chain simultaneously, it showed only yellow emission corresponding to the main chain chromophore, i.e., PPV backbone. Energy transfer from CF3–stilbene into PPV segment should contribute such phenomena to show only emission of lower energy.

Synthesis and Characterization of Poly (2-Methoxy-5-Ethylhexylthio-1,4-Phenylenevinylene)

Abstract New alkylthio group substituted PPV derivative, poly (2-methoxy-5-ethylhexylthio-1,4-phenylenevinylene) (PMEHTPV) was synthesized and characterized with electrical conductivity, UV-VIS, IR and photoluminescence spectrum. The effects of substitution on the electronic and optical properties are discussed in this study.

Synthesis and Properties of Poly(2-Methoxy-5-Propagyl-Oxy-1,4-Phenylenevinylene)

Abstract New PPV derivatives containing cross-linkable acetylene groups, poly(2-methoxy-5-propagyloxy-1,4-phenylenevinylene) (PMPPV) and its PPV copolymers were synthesized through the soluble precursor polymers. PMPPV film was higly cross-linked and lost its properties of a conjugated polymer at over 200 °C. The electrical conductivities of PMPPV films were measured by four probe method after FeCl3 doping. The undrawn and 10 times drawn PMPPV films showed thier electrical conductivities of 1.5 × 10−1 and 92 S/cm, respectively. Conjugation length of poly(PV-co-MPPV) was controlled by changing the PMPPV monomer feed ratio.