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Modified fly ash is a potential competitive sorbent for flue gas mercury remove in coal-fired power plant. The adsorption characteristics of coal fly ash under different temperature and modification methods were studied. On-line modified fly ash as a sorbent for mercury removal at a coal-fired power plant was carried out. The results of laboratory show that the adsorption performance of a coupled bromide and mechanical modified fly ash was better than that of inherent fly ash and mechanical modified fly ash. Furthermore, it was found that high temperatures are more favorable for mercury adsorption. In a demonstration at a full-scale 1000 MW coal-fired power plant unit, injection of the bromide and mechanical modified fly ash resulted in a decrease of the total concentration of mercury emissions at the stack. Additionally, a decrease in Hg2+ from the SCR to the ESP was found. When injected modified fly ash, the final emission concentration of mercury at the unit outlet reached 1.15 μg/m3, with a mercury emission reduction efficiency of 56.1%.

Corrosion products from water-cooled wall of a coal-fired power plant in China were finely collected and further split into samples of different layers along their growth direction. The physicochemical properties of all the samples were well characterized for understanding the mechanisms of high temperature corrosion. The results showed that sulfide type corrosion occurred at the water-cooled wall in the coal-fired power plant. Corrosion products were layered structures. The samples of the outer layer showed loose and porous structures, while the samples of the inner layer were dense structures. The major elemental components of the corrosion products of different layers were sulfur (S) and iron (Fe). The distribution of both S and Fe in the samples of different layers were varied, showing a decreasing trend in the samples from the inner layer to the outer layer. Iron sulfide and magnetite were the major mineral components of the corrosion products, and the content of the iron sulfide decreased in the samples from the inner layer to the outer layer. However, some alumina-silicate from the fly ash generated from the coal combustion was also found attached to the intermediate and outer layers of the corrosion products.

Kinetic analysis of Indonesian lignite washery tailings (LWT) was studied in this paper. Two methods were compared to evaluate the activation energy E of LWT, i.e., iso-conversional methods and model-based method. The Flynn–Wall–Ozawa method and the Kissinger–Akahira–Sunose method were chosen to represent the iso-conversional method. The Coats–Redfern method was chosen as the model-based method. Furthermore, a complementary method of iso-conversional and model-based was also used to determine the kinetic mechanism of LWT. The results provide useful information for designing a combustion or pyrolytic system using LWT as feedstock.

The rheological properties and stability of lignite washery tailing suspensions (LWTS) were studied as a special type of coal water slurry (CWS). The properties of LWTS in these aspects are all shown to meet the requirement of a CWS. Two test methods, i.e., a rotational viscometer and a pipeline test system, were used to study the rheological properties of the LWTS and to distinguish between theory and practice. Furthermore, a rheological model of LWTS transfer in the pipeline test system was proposed and proved to be suitable and useful in designing commercial pipeline systems. Moreover, the influence of an anionic dispersant NDF (a co-polymer of methylene naphthalene sulfonate, styrene sulfonate and maleate) on the stability and rheological properties of LWTS was studied. The dispersant NDF proved to have no effect on the stability of the LWTS, while it significantly improved the rheological properties of the LWTS.

A new functional N-phenylaminomethyl POSS was synthesized by traditionally controlled hydrolytic condensation in one step reaction. The POSS structure was ascribed to a T10 and T12 derivative mixture as main component by varied characterization methods such as 1H NMR, 13C NMR, 29Si NMR, gel permeation chromatography (GPC) and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI−TOF MS). Then based on this new POSS reacted with polyether diisocyanate, a series of POSS−PU composites with different POSS concentration was prepared and characterized. The POSS−PU composites showed no macrophase separation up to 52 wt % POSS concentration. The high resolution transmission electron microscopy (HRTEM) images of POSS−PU composites showed a well separated nanostructure of POSS with a typical phase size of 5−10 nm. A critical POSS concentration of 26 wt % was found by DMA, beyond which the POSS−PU showed a permanent network at high temperature. Tg and storage modulus of POSS−PU composit...

A class of ultra low dielectric constant polymethylsilsesquioxane (PMSQ) films with T 8 (Me 4 NO) 8 polyhedral oligomeric silsesquioxanes (T 8 POSS) as double-effective porogen was studied. Through the Me 4 NO − groups of T 8 POSS attacking the Si–O–Si chains of PMSQ, the POSS will be connected to the PMSQ crosslink system. POSS has the cage structure, which acted as the closed pores (≤ 1.5 nm). On the other hand, the Me 4 NO − groups served as the sacrificial template. When they decomposed after annealing, the open pores were then left in the films. The introduction of T 8 POSS can greatly decrease the dielectric constant of PMSQ, and effectively improve its mechanical strength owing to T 8 (Me 4 NO) 8 interconnected with PMSQ. These continuous and smooth films were prepared by spin-coating with thickness in the range of 60–200 nm. The dielectric constant of the films could be controlled by adjusting the proportion of porogen. These films showed good mechanical strength and ultra low dielectric constant. In particular, a POSS/PMSQ film with ultra low dielectric constant of 1.6 and modulus of 7 GPa had been prepared on silicon wafer by spin-coating.

Through the assembly of polyelectrolyte in aqueous emulsion, we synthesized a series of core–shell ionic complex nanoparticles containing anionic polyurethane (PU) and cationic chitosan (CS). The physicochemical properties of PU–CS ionic complex (PU-c-CS) materials were investigated by IR, XPS, DLS, TEM, AFM, general tensile tests, and surface contact angle measurement. It was found that the sizes of the prepared nanoparticles were in the range from 60 to 220 nm, and the films exhibited good mechanical properties. The cell (HUVECs) culture experiments showed that the PU-c-CS films exhibited very low cytotoxicity and supported cell adhesion and growth. Protein (BSA) adsorption was significantly decreased for the PU-c-CS films. Furthermore, the results of prothrombin time (PT) and activated partial thromboplastin time (APTT) indicated that antithrombogenicity of the materials were effectively improved.

Novel, randomly coupled, soluble, segmented polyimide–polydimethylsiloxane (PI–PDMS) copolymers were prepared from aminoalkyl-terminated polydimethylsiloxane (At–PDMS), 4,4′-oxydianiline diamine, pyromellitic dianhydride, and 4,4′-diphenylmethane diisocyanate (MDI). When At–PDMS was introduced into the polyimide chain, the polyimide copolymers exhibited lower dielectric constants and better moisture resistance and mechanical properties. The reductions in the dielectric constant of the PI–PDMS copolymers could be attributed to the incorporation of polydimethylsiloxane (PDMS) into the polyimide chain and the nanopores in the film generated by carbon dioxide evolvement during the reaction. The lowest dielectric constant was 2.58 with 25 wt % PDMS and 5 wt % MDI. In addition, the water contact angles of the resultant copolymers increased from 51 to 109° when the contents of PDMS increased from 0 to 25 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A series of novel block polymers of polyur- ethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, Mn 5 1000), isophrone diisocyanate (IPDI), and 2,2 0 -dimethylol propionic acid (DMPA), followed by ionizing PU prepoly- mer with triethylamine (TEA). The second step involves PU chain-extended by water-soluble chitosan of low mo- lecular weight (Mn 5 5000) by self-emulsion polymeriza- tion method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infra- red spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. 2008 Wiley Periodicals, Inc. J Appl Polym Sci 109: 240-246, 2008

By sequential ring-opening polymerization of ethylene oxide and epsilon-caprolactone, poly(ethylene oxide) (PEO)-poly(epsilon-caprolactone) (PCL) di-block co-polymers with a phosphoryl choline (PC)-terminated group were synthesized. Using FT-IR, NMR, DSC and SEC, the products were characterized and the results proved the successful synthesis of functionalized di-block co-polymer. After blending the products with polyurethane (PU) and casting the result as film, the PEO segments migrated to the surface of the blend and the PCL segments acted as an anchor to fix the co-polymer on PU matrix, while the PEO segments provided PU the hydrophibility to prevent the fibrinogen adsorption on PU. This specific di-block co-polymer and the method of processing are hoped to be applied in the biomedical field to improve the biocompatibility of polymer materials.

The distribution of pores and the mechani- cal properties of materials are the key factors in preparing satisfactory low-k films. In the present study, a kind of sil- sesquioxane-polyethylene glycol (SSQ-PEG) was synthe- sized and used as a template to make the distribution of pores more even in the low-k films. The crosslinking den- sity of films could be adjusted by the sol-gel of tetrame- thoxysilane/dimethoxydimethylsilane with various pro- portions. The porosity of films could also be adjusted with different proportions of pendant PEG chains introduced. A dielectric constant as low as 2.1 had been achieved for nano- porous polyorganosilicate films with good tenacity. 2006

A temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), was grafted onto porous polyethylene membranes by a plasma-induced graft polymerization technique. A wide range of grafting was achieved through variations in the grafting conditions, including the postpolymerization temperature, time, monomer concentration, and graft-reaction medium. The active species induced by plasma treatment was proven to be long-living via a postpolymerization time of 95 h. Different solvent compositions, that is, water, methanol, benzene, and water/methanol, were used as reaction media, and water showed a much higher polymerization rate than the organic solvents. Based on the hydrophilicity of the active species, a mechanism explaining the solvent effect in plasma-induced graft polymerization was examined. Characterizations by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and micro Fourier transform infrared showed that the grafted polymers were located on both the outer surface and inside pores of the membranes. The XPS analysis also confirmed that the polar amide groups tended to distribute more outward when grafted PNIPAAm was in its expanding state than when it was in its shrinking state. Water permeation experiments showed that the permeability of the grafted membranes varied dramatically with a slight temperature change in the vicinity of the lower critical solution temperature (LCST) of PNIPAAm. The effective pore radii of the grafted membranes above and below the LCST could be depicted by Hagen-Poiseuille's law. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3180–3187, 2003

Based on the typical two step polyurethane – urea synthesis, self-crosslinkable polyurethane – urea compounded of poly(tetramethylene oxide), MDI (4,4 0 -diphenylmethane diisocyanate) and extended by AEAPS (aminoethylaminopropyltrimethoxysilane) were prepared. On the other hand, a C60-amine adducts by reacting C60 with excessive APES (aminopropyltrimethoxysilane) were synthesized and introduced into the polyurethane – urea to form the homogenous and transparent C60 containing polyurethane – urea films. FT-IR, UV, Electron Spectroscopy for Chemical Analysis, Wide-angle X-ray diffractions, dynamic mechanical thermal analysis and mechanical properties of samples were recorded. The optical limiting properties were also measured. The results show that the C60 containing polyurethane – urea is a kind of homogenous material with the ranging of C60 content. The solution state before processing makes it easy to be cast as variety configurations. With the difference in C60 content in polymers, the optical limiting properties are various and the required transmittance and transmitted energy can be altered with the C60 contents in polymers. q 2003 Elsevier Science Ltd. All rights reserved.

Based on the typical two-step polyurethane- urea synthesis, a new series of self-crosslinkable polyure- thane (PU)- urea formulations, consisting of poly(tetrameth- ylene oxide) and 4,4-diphenyl methane diisocyanate, and extended by ethylenediamine (EDA)/aminoethylaminopro- pyltrimethyoxysilane (AEAPS), were prepared. FTIR, ESCA, WAXD, DSC, and mechanical properties of samples were recorded. The results show that the self-crosslinkable poly- urethane- urea could be crosslinked by hydrolysis of the trimethyloxysiloxane group to form the silsesquioxane structure. These structures represent a kind of nanosize, cagelike, chemical crosslink site as well as filler, which affect the properties of PU. The morphology, varied with different ratios of EDA/AEAPS, was also discussed. © 2003 Wiley

The high melting point of poly(1,4-cyclohexanedicarboxylic anhydride) [poly(CHDA)] is a disadvantage, in that it is intractable in the melting process of a drug delivery system. This report relates to diols introduced into the polyanhydride main chain to decrease its melting point. Various poly(ester anhydride)s containing ethylene glycol, 1,3-propanediol, 1,4-butanediol, or 1,6-hexandiol [poly(CHDA–XDO)] were synthesized by the esterification reaction and melt polycondensation. FTIR, DSC, WAXD, and intrinsic viscosity of polymers were recorded and hydrolytic degradation, as well as in vitro drug delivery, was conducted. The results show that the samples are stable in an anhydrous environment at room temperature and degrade in water following a surface erosion mechanism. The degradation period of poly(CHDA–XDO) ranged from 130 to 320 h as a result of the different diols and amounts of XDO introduced. The in vitro drug delivery gave 130–350 h of stable delivery along with the typical surface erosion mechanism. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2509–2514, 2002

Polyurethane (PU) prepolymers based on isophorone diisocyanates, dimethylolpropionic acid, and polycaprolactone were prepared and chain- extended in water using L-lysine (PU–L), ethylenediamine (PU–E), and their mixture (PU– L–E) as extenders, respectively. The produced emulsion exhibited satisfactory freeze/thaw stability. Films cast from emulsions exhibited excellent mechanical properties and good antiblood coagulation character. Although the water-swelling ratio for 24 h for PU–L was higher than those of PU–L–E and PU–E, it possessed the smallest hydrolysis rate among the three samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2474–2480, 2002

A series of blends of thermoplastic polyurethane(PU) and polyether–polyimide (PI) were prepared in two steps. The first step was the preparation of polyether–amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol di-p-aminobenzoate (APTMO) of different molecular weight (650, 1000, and 2000) with benzenetetracarboxylic acid dianhydride (PMDA). The second step was mixing polyether–polyurethane and polyether–polyamic acid solution at room temperature in various weight ratios, and the blend films were obtained by casting and then heat imidization. Infrared spectroscopy (IR), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), small-angle X-ray scattering (SACS) and wide-angle X-ray diffraction(WAXD) were used to study this family of blends. DSC analysis of the films showed that glass transition temperature (Tg) of PU–PI 650 and PU–PI 1000 series shifted depending on the ratio of PU and PI components. The shift of Tg, along with the transparency of the films, gave the evidence that soft segments of PU and PI were miscible to some extent in the PU–PI 650 and PU–PI 1000 series. DMA results indicated that the blends exhibited a well phase-separated structure and had a broad rubbery plateau from about −30 to 200°C, which varied with the PU content. Thermal stability of PU was found to increase by the incorporation of PI. The excellent tensile properties of the blends suggested that they could be potentially used as heat resistant thermoplastic elastomers.

Polycaprolactone containing carboxyl groups (CPCL, Mn = 1200) was prepared from caprolactone (CL) and dimethylol propionic acid (DMPA). Based on the CPCL, 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD), a novel series of polyurethane ionomers could be synthesized with ions in the soft segment. The tensile modulus and ultimate elongation of the ionomer cast films increased, and the glass transition temperature of the CPCL-rich phase moved to a higher temperature after ionization. Moreover, this kind of ionomers showed small amounts of hard segment crystallinity by DSC. WAXD shows an ionic peak at 2θ = 8.6° for the ionomer with carboxylate in the hard segment, which is not present in the ionomer with carboxylate in the soft segment. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 2049–2056, 2000

A series of polyurethane (PU) emulsions modified with aminosilicone were synthesized, based on 2,4-toluene diisocyanate (TDI), poly(tetramethylene oxide) (PTMO), and dimethylolpropionic acid (DMPA) as a prepolymer which was chain-extended with aminoethylaminopropyl polydimethylsiloxane (AEAPS) in an aqueous emulsion. Their chemical compositions, structures, bulk and surface properties, and emulsion morphologies were investigated using Fourier transform infrared spectrum analysis (FTIR), tensile and surface contact angle measurements, electron spectroscopy for chemical analysis (ESCA), water swellablity, an emulsion stability test, and transmission electron microscopy (TEM). It was shown that the PU emulsions were stable and the siloxane chains were enriched on the PU surface. The water resistance of the PU film increased but the bulk tensile properties of the PU film were not changed significantly with a small amount siloxane modification up to 6 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 295–301, 2001

A series of polyurethanes with different siloxane contents were synthesized, which were based on 4,4′-methylene diphenyl diisocyanate (MDI), poly(tetramethylene oxide) (PTMO), aminoethylaminopropyl poly(dimethyl siloxane) (AEAPS), and butanediol (BD). The chemical compositions, structures, and bulk and surface properties were investigated using an infrared surface quantitative analysis technique (FTIR-ATR), surface contact angle, electron spectroscopy for chemical analysis (ESCA), stress–strain analysis, and dynamic mechanical thermal analysis (DMTA). It was shown that siloxane concentration on the surface region of the elastormers was higher than that in the bulk for a resulting surface enrichment of the siloxane, and the tensile properties of these elastomers were not changed significantly with the AEAPS modification. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2552–2558, 1999

Based on aromatic diisocyanate [e.g., 2,4-tolylene diisocyanate (TDI)], a novel synthetic strategy to waterborne polyurethanes was introduced. Ionized polyoxyethylated amine (NPEO) played an important role in the preparation process as both a polyether soft segment and an internal emulsifier. First, a segmented surfactant prepolymer was synthesized. Second, the prepolymer was charged to a water dispersion of a hydrophobic polyol [e.g., polytetrahydrofuran (PTMO)] directly to obtain a stable emulsion. Third, a chain-extension procedure was performed directly in water with PTMO to achieve a stable aqueous polyurethane dispersion. Neither aliphatic diisocyanate nor excess isocyanate group fraction was added. An extra end-capping reaction or external emulsifier was also unnecessary. Films cast from emulsions exhibited reasonable mechanical properties. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1621–1626, 1998

Side chain liquid crystalline polyurethanes (SCLP) without flexible spacer were synthesized by a two step block copolymerization reaction. The polyurethanes were based on azobenzene-type mesogenic diol chain extender (DR-19), a poly(tetramethylene oxide) (PTMO) soft segment, and different diisocyanates, including 4,4-diphenylmethane diisocyanate (MDI) and hexamethylene diisocyanate (HDI). The polyurethane samples obtained from DR-19 or DR-19 . and PTMO with HDI had mesomorphic phases as determined by DSC and polarizing microscopy.

Based on polyoxyethylated amines (Mn = 600, 1,200) derived from n-butyl amine and ethylene oxide, 4,4′-diphenylmethane diisocyanate, and different chain extenders, two series of polyether–polyurethane (PU) ionomers with reasonable mechanical properties were synthesized. Chain-extended by 1,4-butanediol and subsequently reacted with 1,3-propane sultone, PU elastomers can be conveniently converted to PU zwitterionomers whose ions are located in polyether soft segments. Chain-extended by N-methyl diethanolamine or sodium-S-1,2-dihydroxypropyl sulfonate along with ionization by 1,3-propane sultone, PU ionomers with ions incorporated into both hard and soft domains can be prepared. Physical properties were studied by means of Fourier transform infrared spectra, differential scanning calorimetry, and uniaxial stress–strain testing. Complex impedance spectra were also measured to estimate solid-state ionic conductivity. The results show that ionization of both hard and soft segments induced a much decreased glass transition temperature and brought higher ionic conductivity at room temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2179–2185, 1998

In this study, a series of polyether-ester ionomers was prepared by neutralizing the carboxylic acid groups in 1: 1 copolymers of benzenetracarboxylic dianhydride (BTDA) and poly(tetramethylene oxide) or poly(ethylene oxide) glycol. The base polymers were in a liquid state while the ionomers were in solid state and a separate ionic phase was formed. The local structure and the morphology of the ionomers were investigated by dynamic mechanical analysis, Fourier transform infrared spectroscopy, and small-angle x-ray scattering as well as extended x-ray absorption fine structure. Clearly, the geometric structure of the ionic sites varied with the nature of the metal ions and the morphology of the ionomers was determined by the microstructure of the ion aggregates.

A series of polyether (PTMO, PEO) polyurethane ionomers having different contents of sodium sulfonate groups in the soft segments have been synthesized. The reaction of transesterification was involved in the incorporation of the sodium sulfonate groups in the polyether. The polyurethane ionomers were characterized by means of dynamic mechanical thermal analysis, differential scanning calorimetry, and small-angle x-ray scattering. Solid-state ionic conductivity was also measured. As the ionization level increased, the compatibility of the hard and soft segments increased and the glass transition region of the soft segment became broader. These samples had relatively higher moduli and good film-forming ability. Moreover, this kind of ionomer provides a very promising ionic conductive multiphase polymer with a single ion transport mechanism. © 1997 John Wiley & Sons, Inc.

Liquid crystalline polyurethane elastomers (LCPUE) were synthesized by a two-step block copolymerization reaction. The main-chain LCPUE were based on two azoxybenzene-type mesogenic diol chain extenders (HA2 and HA6), a poly(tetramethylene oxide) (PTMO) soft segment, and different diisocyanates, including 4,4′-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI). The polyurethanes were characterized by FTIR, DSC, DMA, WAXD, UV, and polarized optical microscopy. Most of the polyurethane samples exhibited nematic thermotropic liquid crystal behavior and had physical properties typical of thermoplastic elastomers. The liquid crystal properties were strongly related to the interaction between the hard and soft segments of the polyurethane. As the compatibility of the soft and hard segments increased, the thermal stability of the liquid crystal phase and the transition temperatures decreased and the range of the transition became narrower. © 1996 John Wiley & Sons, Inc.

A series of polyurethane organometallic complexes based on novel diols, bis[N-[[2-hydroxyphenyl]methylene]hydroxylethyleneamino]-copper(II) (DBSICu), were synthesized successfully. The products are elastomeric glassy materials or powders. Similar to other polyurethane elastomers, these coordination block copolymers exhibit 2-phase microstructure and thermoplastic properties. It is interesting to note that some of these polyurethanes show a Schlieren pattern under the polarizing optical microscope. The liquid crystalline properties of DBSICu and the coordination polymers are studied in detail in this study.

Simultaneous Interpenetrating Networks (SINs) were synthesized based on polyepichlorohydrin glycol (PECG), toluene diiocyanate (TDI), and trihydroxymethyl propane (TMP) as network I; and methyl methacrylate (MMA), ethyl methacrylate (EMA), methyl acrylate (MA), ethyl acrylate (EA), and ethyleneglycol dimethylacrylate (EGLM), respectively as network II. Damping behavior of the SINs was studied by a dynamic viscoelastometer. It was found that loss factor, tan δ, of PU/PEMA and PU/PEA is much higher than that of PU/PMMA and PU/PMA. The present authors consider that the length of pendant groups has an influence on the height of tan δ in the interpenetrating structure. Transmission electron microscopy (TEM) photos show that the SINs possess multiphase structures. These two networks are dispersed in a system microheterogeneously. © 1994 John Wiley & Sons, Inc.

Liquid crystalline polyurethane elastomers (LCPUE) have been synthesized by a two-step block copolymerization reaction. The main-chain LCPUEs are based on two biphenyl-type mesogenic diol chain extenders (HB2 and HB6), a poly(tetramethylene oxide) (PTMO) soft segment, and different diisocyanates, icluding 4,4′-diphencylmethane diisocyanate (HDI), and 1,4-(3,5,5-trimethyl)cyclohexane diisocyanate (IPDI). The polyurethanes were characterized by FTIR dichrosim, DSC, DMA, WAXD, and polarized optical microscopy. Most of the polyurethane samples exhibited nematic thermortopic liquid crystal behavior and had physical properties typical of thermoplastic elastomers. The liquid crystal properties are strongly related to the interaction between the hard and soft segments of the polyurethane. As the compatibility of the soft and hard segments increased, the thermal stability of the liquid crystal phase and the transition temperatures decreased and the range of the transition became narrower, Uniaxial extenstion analysis shows that two orientation mechanisms exist in the LCPUE systems. These samples had fairly high strength and modulus and good membrane-forming ability. © 1994 John Wiley & Sons, Inc.

Soft-segment molecular weight, soft-segment crystallization, hard-segment-type, and reactive diluent level were examined in urea and urethane acrylates. Increasing soft-segment molecular weight led to a decreased tensile modulus, increased strength, and increased elongation at break. Soft-segment crystallization increased the modulus below the melting temperature, but decreased the modulus above the melting temperature because crystallization interfered with cross-linking. Materials with hard segments that allowed for greater phase separation showed a higher modulus, higher ultimate stress, and higher ultimate elongation. Materials with reactive diluents 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidinone (NVP) showed qualitatively different behavior. HEMA caused the modulus and strength to increase with little effect on elongation up to concentrations of 50 wt %; at higher concentrations, the elongation decreased. NVP also increased the modulus and strength; however, at 40 wt % NVP, ultimate elongation increased in a well-phaseseparated system and decreased in a poorly phase-separated system. In tensile tests, samples with 40% NVP also showed substantial sample necking and drawing. © 1993 John Wiley & Sons, Inc.

Polymers containing amic acid units were produced by reacting an oligomer based on polytetramethylene oxide (PTMO) with 1,2,4,5-benzenetetracarboxylic dianhydride (BRDA). Neutralization by a metal salt produced amic acid ionomers. Similar to other ionomer systems, neutralization from the acid to the ionomer led to the formation of a separate ionic phase as determined by dynamic mechanical analysis. Phase separation resulted in a substantial increase in mechanical properties. The effect of neutralization level, cation, soft-segment molecular weight, and soft-segment end group on mechanical and thermal properties was investigated.

Surface-enhanced Raman scattering (SERS) has been intensely researched for many years as a potential technique for highly sensitive detection. This work, through the reduction of HAuCl(4) with pyrrole in aqueous solutions, investigated a facile one-pot synthesis of flower-like Au nanoparticles with rough surfaces. The formation process of the Au nanoflowers (AuNFs) was carefully studied, and a spontaneous assembly mechanism was proposed based on the time-course experimental results. The key synthesis strategy was to use pyrrole as a weak particle stabilizing and reducing agent to confine crystal growth in the limited ligand protection region. The nanometer-scale surface roughness of AuNFs provided several hot spots on a single particle, which significantly increased SERS enhancement. Good biocompatible stable Raman-active probes were synthesized by coating AuNFs with chitosan. The conservation of the SERS effects in living cells suggested that the chitosan-capped AuNFs could be suitable for highly sensitive detection and have potential for targeting of tumors in vivo.

A series of polyether–polyimides based on polycondensation of poly(tetramethylene oxide) glycol di-p-aminobenzoate with different molecular weights (650, 1000, 2000) and benzenetetracarboxylic acid dianhydride (BTDA) or 3,3′,4,4′-benzenetetracarboxylic acid anhydride (BPTDA) was synthesized. Infrared spectroscopy (IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and stress–strain tests were used to follow the imidization process and to study the structure–property relations of this family of polymers. FTIR data showed that the imidization was completed after 6 h at 140°C, which is a much lower temperature than that required for polyimides synthesized from low molecular weight diamines. DSC and DMA results indicated that the block copolymer exhibited a well-phase-separated structure and had a broad rubbery plateau from about −70°C to 260°C, which varied with dianhydride type and hard-segment content. The BTDA series had enhanced mechanical properties compared to the BPTDA series. The excellent tensile properties of the polyether–polyimides suggest that they could be potentially used as heat-resistant thermoplastic elastomers.

Castor oil was reacted in varying ratios with β-isocyanatoethyl methacrylate to form a liquid urethane–methacrylate prepolymer. This prepolymer was then cured using ultraviolet radiation to form a series of base polymer networks or using various methacrylates to form conetworks. By swelling the base networks with the appropriate methacrylate monomers, semi- and full interpenetrating networks (IPNs) were prepared with similar compositions. All of the materials formed transparent films. Results of swelling experiments, dynamic mechanical analysis, differential scanning calorimetry, and small angle x-ray scattering are discussed.

Propyl sulphonate groups were grafted on to the backbone of Biomer ®, a polyetherurethaneurea, in an attempt to improve its blood-contacting properties. The bulk, surface and blood-contacting properties of this series of sulphonated polymers were evaluated. Differential scanning calorimetry and dynamic mechanical analysis indicated that propyl sulphonate incorporation increased the microphase separation of the polymers. The ultimate tensile strength was also increased with sulphonation at the expense of the polymer's extensibility. Dynamic contact angle analysis showed that, in water, the sulphonated Biomer® surfaces were more polar than the Biomer® sample indicating the propyl sulphonate groups were enriched at the surface. Canine ex vivo blood-contacting results showed that the incorporation of propyl sulphonate groups dramatically reduced the number and activation of platelets adherent to the polymer surface. In addition, fibrinogen deposition increased with increasing sulphonate content, despite the low level of platelet activation.

The effects of chain architecture, polyol chemistry and polyol molecular weight on the properties of elastomeric polyurethane ionomers were investigated. The type of polyol and its molecular weight had a strong influence on the rubbery modulus and tensile properties. Variations in chain architecture showed little impact on mechanical and thermal properties. Linear ionomers, threearm ionomers, and six-arm ionomers had similar mechanical and thermal behavior.

Polyanhydrides for drug-controlled release systems from cis- and trans-1,4-cyclohexanedicarboxylic acid (1,4-CHDA) were synthesized by melt polycondensation. The degradation of polymers was estimated by weight loss in 0.1 mol l(-1), pH 7.4 phosphate buffer at 37 degrees C. The drug delivery was conducted in the same buffer. The results show that the different polymers lost weight over 150-360 h, and fine surface erosion was investigated. The different conformation of CHDA has an obvious influence on the degradation of polyanhydrides due to their different crystallinity, with higher crystallinity samples degrading much more slowly. The incorporation of adipic acids into the poly(CHDA) can obviously accelerate the degradation and the introduction of -CH2- segments increased the flexibility of polyanhydride backbone and accelerated the degradation rate. In vitro delivery experiments show that Bruffen was completely released in about 10 days from a melting mold disk with a fine linear delivery curve.

Ionic metal-fullerene adducts C60M ( M = Li+, Mg2+, Ca2+, Sr2+, Ba2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, A13+ Ag+, Ce3+ ) are synthesized by reaction of watersoluble C60Lin with metal salt. 13C NMR of C60Li in D20 gives a sharp peak at 171.44 ppm which is much higher than the chemical shift of C60 in benzene ( 142.98 ppm ). Elemental analysis suggests the state of C60 in the adducts is C605-. ESR spectra of the adducts show a strong narrow peak at 9=2.001. UV-Vis and IR spectra of those adducts are completely different from those of C60. Magnetic measurement indicates that C60Li, C60Ce are antiferromagnetism and C60Fe adducts is ferromagnetism in the range of 150–300 K. But C60Fe adduct becomes paramagnetism when temperature is lower than 150 K. Mossbauer spectroscopy indicates Fe3+ in C60Fe adduct is Fe3+ (I.S.=0.30 mm/s, Q.S.=0.67 mm/s). The experimental results strongly suggest that C605- is a stable single free radical polyanion of fullerene which is a weak acid radical and possesses the similar properties with general inorganic anion. This is the first report on the synthesis and properties of air-stable and water-soluble polyanion of fullerene( C605-). A method for preparing metal-fullerene adducts has been developed, and many unusual properties of the adducts are found.

Ethylene oxide units were incorporated into the backbone of Na+ sulfonated polyurethane ionomers in an attempt to induce aggregate dissociation at elevated, but observable, temperatures by reducing the incompatibility between ions and polymer. However, no dissociation could be observed by small-angle x-ray scattering (SAXS) before the onset of degradation, even when the polyol was pure EO. At 100°C and above, the SAXS patterns for all samples were quite similar, indicating morphological similarity. However, after annealing for several days at room temperature, two of the specimens appeared to develop a greater degree of microdomain order as evidenced by a narrowing of the main peak at q* and the development of a shoulder at 2q*x.