Tian-Ming Chen

Electroluminescent devices based on polymers forming hole-transporting layers. II. Polyimides containing β-naphthyldiphenylamine units

Two polyimides, PI(C1-BA) and PI(C1-6FDA), based on an aromatic di- amine compound and two aromatic dianhydrides (biphenyltetracarboxylic dianhydride (BA) and 4,49-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)) were newly syn- thesized. They were characterized by viscosity, Fourier transform infrared measure- ments, and X-ray analyses. X-ray results revealed that the crystallinity of PI(C1-BA) was lower than that of PI(C1-6FDA). The synthesized polyimides could be formed into stable and homogeneous thin films on an ITO (indium tin oxide) electrode, functioning as good hole-transport materials for organic electroluminescent (EL) devices. The double-layered EL devices, consisting of the hole-transport layer of these polyimides and an emitting layer of tris(8-quinolinolato)aluminum complex, exhibited a peak emission wavelength in the bright green at 524 -527 nm. Moreover, a maximum luminance of 355 cd/m 2 was achieved at a voltage of 13 V, with a current density of 600 mA/cm 2 for the EL device using PI(C1-BA) as a hole-transport layer. The phenomenon of an extended luminance of these EL devices was also found when the voltage was

Synthesis and properties of phospholipid polyurethanes with poly(isoprene) soft segment

Polyrethanes, based on 2-[bis(2-hydroxyethyl)methylammoni]ethylstearylphosphate, alone or together with 1,4-butanediol as the chain extender, poly(isoprene) diol and 4,4′-methylenediphenyl diisocyanate, were prepared. These segmented phospholipid polyurethanes were characterized by IR, elemental analyses, and gel permeation chromatography. The polyurethane, with both phospholipid diol and 1,4-butanediol as the chain extender, was further investigated by differential scanning calorimetry, x-ray diffraction, scanning electron microscopy, plasma contact and clotting time. An x-ray diffraction measurement for the polymer shows a intense scattering at 79.3 A corresponding to the length of soft segments, which is hydrophobic poly(isoprene), and a weak diffuse scattering at 5.1 A corresponding to the distance between the hydrophobic poly (isoprene) layers. The hemocompatibilities of the polymer were evaluated by platelet rich plasma contacting studies and by scanning electron microscopy using medical grade poly(vinyl chloride) as control. The hot-pressed films of the polymer exhibit a favorable surface in terms of platelet adhesion, and the morphology of adhered platelets undergoes to a relatively lower degree of variation compared to poly(vinyl chloride). Moreover, the clotting time of the polymer in contact with human platelet rich plasma was 220, 100, and 86 s for the phospholipid-based polyurethane, poly(vinyl chloride), and glass, respectively.

Electroluminescent devices based on polymers forming hole transporting layers, 1. Polyimides containing o-tolidine units

Two polyimides, PI(BA-TD) and PI(6FDA-TD), based on an aromatic diamine (TD) and two aromatic dianhydrides (BA, 6FDA) were synthesized. They were characterized by viscosity, FT-IR, and X-ray photoelectron spectroscopy (XPS) measurements. XPS results reveal that the binding energy of C 1s , N 1s , and O 1s in PI(BA-TD) is lower than that in PI(6FDA-TD). The synthesized polyimides form stable and homogeneous thin films on an ITO electrode, functioning as good hole transporting materials for organic electroluminescent (EL) devices. The double-layered EL devices consisting of a hole transporting layer of these polyimides and an emitting layer of the tris(8-quinolinolato)aluminium complex exhibit a peak emission wavelength in the bright green at 521∼525 nm. Furthermore, a maximum luminance of 97 cd/m 2 was achieved at a voltage of 15 V with a current density of 192 mA/cm 2 for the EL device using PI(BA-TD) as a hole transporting layer. The phenomenon of an extended luminance of these EL devices was also found when a voltage higher than 15 V was applied.

Studies on the synthesis and properties of novel phospholipid analogous polymers

Two kinds of phospholipid analogous compounds, methacrylate monomers (4a-b) and acrylamide monomers (5a-b), were prepared and polymerized with a radical initiator in water at room temperature. The viscosity behavior of these charged polymers were investigated in the presence or absence of inorganic salts, and the found inherent viscosity [η] of amide polymer (poly7a) is higher than those of ester polymers (poly6a1 and poly6b). On the other hand, the radical copolymerization of monomer 5b with acrylamide (AAm) was also carried out in water. Based on the x-ray analyses, it is proposed that some of the obtained polymers show ordered bilayer structures in condensed phase. Furthermore, the thermal properties were studied by DSC anti TG-DTA measurements.

Synthesis and properties of poly(acrylamide)s containing both long chain alkyl groups and phosphatidylcholine analogues in the side chains

A series of new phospholipid analogous acrylamide monomers (4a-e) containing long alkyl chains as hydrophobic groups and containing phosphatidylcholine analogues as hydrophilic group were synthesized in high yields. The homopolymerizations and copolymerization (4b with 4e) were carried out in the presence of a radical initiator. The structures and thermal properties of these polymers were investigated by x-ray diffraction analysis, DSC, and polarizing microscopy measurements. It has been revealed that these homopolymers (5b, 5c, and 5d) which bear saturated long-hydrocarbon chains in the side chains exhibited not only orderly stacked bilayer structures at room temperature but also clear liquid crystalline behavior within a wide temperature range. The viscosity behavior of all polymers was found similar to usual polyelectrolytes in porlar solvent. The polymers obtained were also characterized by 1 H-NMR, IR, and melting point, respectively.

Yellow green electroluminescnece generated from the thin films of β-diketone-zinc complex

A novel zinc complex, Zn(NDP)2 (NDP = 2-naphthyl-7-dimethylamino-1,3-propanedione), was synthesized and applied to an organic electroluminescent (EL) device as an emitting material and an electron-transporting material. The double-layered EL device has been fabricated by using triphenyldiamine derivative (TPD) as a hole-transporting layer and Zn(NDP)2 as an active emitting layer sandwiched between indium-tin oxide (ITO) and an alloy of Al/Li (99:1) electrodes. The deposited EL device was observed to emit a yellow-green light originating from Zn(NDP)2 with a maximum luminance of 1000 cd/m2 at 14 V and 200 mA/cm2.

Studies on syntheses and properties of novel polyamides containing phosphatidylcholine analogous moieties by interfacial polycondensation

Polyamides (4a-b and 5a-b) were synthesized from interfacial polycondensation of novel diamine containing phosphatidylcholine analogous moiety, hexamethylene diamine with adipoyl chloride, or sebacoyl chloride in the interface of water and carbon tetrachloride at room temperature. The characterizations of synthesized diamine and polyamides were carried out with FT-NMR, or IR spectral method, elemental analysis, and melting point measurements, respectively. These polyamides obtained are insoluble in any normal solvents. From the results of X-ray diffraction analysis and POM observation, it was revealed that the polyamide 4b was prepared with high molecular weight, while polyamide 4a obtained seemed to have low molecular weight. For copolymers 5a and 5b, X-ray reflections from only adipoyl or sebacoyl chloride parts were observed as in crystalline state. In addition, thermal properties were also studied by DSC and transmitted light intensity measurements.

Structure in the condensed state and amphiphilic properties of novel copolymers having alkyl chains and phosphatidylcholine analogous groups

N-Stearylacrylamide (SAAm), N-oleylacrylamide (OAAm), and N-laurylacrylamide (LAAm) were synthesized. They were characterized by 1H-NMR, 13C-NMR, FT-IR, melting point measurements, and elemental analysis. The copolymerizations of SAAm, OAAm, and LAAm with 2-[(3-(acrylamido)propyl)dimethylammonio]ethyl 2′-isopropyl phosphate were carried out, and a series of amphiphilic poly(acrylamide)s (1a,b, 2, and 3a,b) were obtained. These copolymers showed polyelectrolyte behavior in their viscous properties in polar solvents. X-ray diffraction analysis indicated that the copolymers 1a,b formed similar stacked bilayers with hydrophilic groups and hydrophobic parts. The polymorphic phase transition of these copolymers was also observed by DSC. In addition, the monolayers as well as LB films of these amphiphilic copolymers were prepared on the surface of water and their π–A isotherms were investigated at different temperatures.

SYNTHESIS AND PROPERTIES OF AMPHIPHILIC PHOSPHOLIPID ANALOGOUS POLYACRYLAMIDIC GELS

Abstract New phospholipid analogous acrylamide monomers containing alkyl chains as the hydrophobic groups and phosphatidylcholine analogues as the hydrophilic groups were synthesized. The polymerizations of these monomers were carried out in the presence of α,α′-azobisisobutyronitrile as a radical initiator and N , N ′-methylenebisacrylamide as a cross-linking agent. The obtained gels were found to swell in polar solvents, but shrink in nonpolar solvents. The result of X-ray diffraction analysis proposed that these gels are basically constructed from alternately stacked bilayers with hydrophilic and hydrophobic regions of the side chain. Furthermore, liquid crystalline behaviors for these gels were observed at room temperature.

Synthesis and properties of a new poly(acrylamide) containing phosphatidylcholine analogues and cholesterol groups in side chains

Abstract Amphiphilic acrylamide monomer containing a cholesterol moiety as a hydrophobic group and a phosphatidylcholine analogue as a hydrophilic group was synthesized in high yield. Radical polymerization was carried out in the presence of α,α′-azobisisobutyronitrile (AIBN) as initiator. The obtained monomer and homopolymer were characterized by 1H-NMR, IR and melting point, respectively. The packing structure and thermal properties of the obtained polymer were investigated by X-ray diffraction analysis, DSC measurement and polarizing microscopy observation. It has been proposed that the homopolymer consists of a stacked bilayer structure in a smectic liquid crystalline phase over a wide temperature range. In addition, the monolayers of monomer and homopolymer on the surface of water were investigated at different temperatures and different subphase pH. The optimum condition for preparing stable and order monolayer has been determined as 10 °C and pH 4.0 for a monomer, and over a wide range of temperature (10–30 °C) and pH (pH 4.0–10.0) for a homopolymer.