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A series of new monomers of 2,5-bis[(4-tertbutyl-phenyl)-1,3,4-oxadiazole] styrene (M-Ct) and 2,5-bis[(4-alkoxy-phenyl)-1,3,4-oxadiazole]styrene (M−OCm, m is the number of the carbons in the alkoxy groups, m = 8, 10, 12, 14) were synthesized. Conventional radical polymerization of the monomers resulted in a series of new mesogen-jacketed liquid crystalline polymer (MJLCP) containing the 1,3,4-oxadiazole unit. The chemical structures of the monomers were confirmed by elemental analysis, mass spectrometry, 1H NMR, and IR. The molecular characterization of the corresponding polymers of P-Ct and P-OCms was performed with 1H NMR, gel permeation chromatography, and thermogravimetric analysis. Their phase structures and transitions were investigated by differential scanning calorimetry, wide-angle X-ray diffraction, and polarized light microscopy experiments. The P-Ct formed the hexatic columnar nematic (ΦHN) phase that is typical for MJLCPs, wherein the chain molecules were rodlike. The P-OCms exhibited a well-defined smectic A (SA) phase. As the mesogenic group is laterally jacketed to the polyethylene backbone through a single carbon−carbon bond, the P-OCm molecule in the SA phase should be more or less ribbonlike with the backbone squeezed by the parallel aligned side chains on both sides. The transition of the four P-OCms follows the sequence of SA ↔ N ↔ I. The comparison between P-Ct and P-OCms indicates that the flexibility of the side-chain tails is crucial to determine the LC structures. Namely, simply changing the chemical structures of small portion of the MJLCP may greatly vary the molecular packing behavior and thus the molecular shape in LC phase structures.

The nitroxide‐mediated radical polymerization of styrene was carried out on the surfaces of multiwalled carbon nanotubes (MWNTs) initiated by an MWNT‐supported initiator multiwalled carbon nanotube–2″,2″,6″,6″‐tetramethylpiperidinyloxy (MWNT–Tempo). The content of polystyrene grafted from the surface was controlled by changes in the polymerization conditions, such as the reaction times or the ratios of monomers to initiators. The obtained polystyrene‐grafted multiwalled carbon nanotubes (MWNT–PSs) were further used to initiate the polymerization of 4‐vinylpyridine to get polystyrene‐b‐poly(4‐vinylpyridine)‐grafted multiwalled carbon nanotubes (MWNT–PS‐b‐P4VPs). In contrast to unmodified MWNTs, MWNT–PSs had relatively good dispersibility in various organic solvents, such as tetrahydrofuran, CHCL3, and o‐dichlorobenzene. The structures and properties of MWNT–PSs and MWNT–PS‐b‐P4VPs were characterized and studied with several methods, including thermogravimetric analysis, Fourier transform infrared, ultraviolet–visible, and transmission electron microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4656–4667, 2006

A series of waterborne polyurethanes (WPUs) with different contents of reactive organophosphonate were well prepared. Their structures were characterized by Fourier transform infrared and 1 H-NMR spectroscopy. Thermogravimetry and derivative thermogravimetry revealed that the WPU films containing phosphorus possessed lower onset and maximum degradation temperatures but higher char yields. Differential scanning calorimetry analysis suggested phase mixing of the hard and soft domains. The mechanical properties decreased with increasing amount of organophosphonate, whereas the limiting oxygen index results of the WPU films indicate that the flame retardancy was improved significantly by the incorporation of organophosphonate. The water uptake values of the organophosphonate-containing WPU films were higher than those of the phosphorusfree ones, whereas the static contact angles of the films indicated that the surface hydrophilic properties were not affected by segmenting in this phosphorus-containing oligomer.

A series of copolymers PCt‐co‐Poly(N‐vinylcarbazole) were synthesized through common radical polymerization, in which P‐Ct as a kind of mesogen‐jacketed liquid crystalline polymer was introduced, and the effects of copolymers composing variation on the optical properties of the polymers were studied. The structures and properties of the copolymers were characterized and evaluated by thermogravimetric (TGA), UV, photoluminescence (PL), cyclic voltammetry (CV), and electroluminescence (EL) analyses. All the polymers enjoy high thermal stability. PL peaks in the film show blue‐shift compared with in solutions and fluorescent quantum efficiency decreased with the N‐vinylcarbazole (nvk) content increasing, which supported the efficient energy transfer from nvk units to the oxadiazole units. CV revealed that, with the incorporation of nvk to the copolymer, these copolymers had high‐lying HOMO energy levels ranging from −5.94 to −6.09 eV. Single‐layer light‐emitting diodes (LEDs) with the configuration of ITO/PEDOT/PCt‐nvk/Mg:Ag/Ag were fabricated, which emit a blue light around 450 and 490 nm with a maximum luminance of 703 cd/m2. The device performance varies with the content of nvk and device configuration, with device configuration (b) and PCt‐nvk8 giving the best value of external quantum efficiency of 0.27%. We show here that by proper design copolymer structure and modification of device configuration can exhibit strong blue EL in higher external quantum efficiency. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1843–1851, 2008

Flame-retardant waterborne polyurethanes with a phosphorus-containing flame retardant diamine (AWPUs) were synthesized and characterized by the method of post-chain extension technology.

The swelling properties of different chitosan-poly(vinyl alcohol) (PVA) hydrogels were investigated as functions of the medium pH and salt concentration. The maximum swelling ability of the hydrogels was at a buffer pH of approximately 3, regardless of the PVA content in the hydrogels. The maximum mass of the swollen hydrogels was about 13 times that of their contracted counterparts. The cyclical swelling and contraction between pH 3 and pH 7 buffers and pH 3 and pH 3 buffers with salt confirmed the Donnan swelling mechanism of these hydrogels. The swelling mechanism was considered the transfer of water molecules driven by a concentration gradient. This was represented by a simplified mass-balance model, which neglected the effect of the ionization reaction, for the initial swelling period. The effective mass-transfer coefficient of water molecules during swelling, estimated with this model, gradually decreased with increasing PVA content in the hydrogels.

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