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BACKGROUND Numerous genetic sequencing projects have demonstrated that alterations in Polε (DNA polymerase epsilon ) due to various causes are associated with the development of multiple human cancers. However, the biological functions of its four core genes, POLE1/2/3/4/, in the occurrence, progression, and prognosis of hepatocellular carcinoma(HCC) remain poorly understood to date. METHODS Multi-omics, multi-level deep mining of HCC data from TCGA and other publicly available databases by using online analysis tools from GEPIA2, TIMER2.0, DAVID, Kaplan-Meier plotter, cBioPortal and MethSurv databases, as well as the R package to assess Polε family members in HCC for their potential biological functions. RESULTS We found that the four target genes were significantly upregulated in HCC (P

Magnetic biochar (MBC) has been proven to be an efficient sorbent for elemental mercury (Hg0) removal from coal-fired flue gas in our previous studies. However, SO3 is an acidic component of flue g...

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%.

Solvent emissions is a serious problem in the industrialization of the amine scrubbing process. To design pollutant control equipment for a 2 million tons/year CO2 capture plant, a bench and a pilot facility were tested to investigate the aerosol emissions. And three Aspen models were built to study vapor emission and design emissions control measurement. The emissions assessment showed the treated flue gas after the absorber was about to discharge 1078 mg/Nm3 aerosol-type solvent and 1055 mg/Nm3 vapor-type solvent. The experimental results of particle size distribution indicated that improving the growth of the submicron droplets before the water wash and demister was the key to control aerosol emissions. Three control methods were compared by simulation, the best control measure was the combination of dry bed and water wash section, and the drain-out water is feed to the top of the dry bed. Considering the economy and control efficiency, the packing height of the water wash section is 2.5 m, and the scrubbing flow rate is 5000 Nm3/h. The extra cooling for the dry bed is not necessary and uneconomic. Under this countermeasure, the vapor emissions solvent is as low as 1.27 mg/Nm3 without additional freshwater for the water wash section.

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.

In this study, manganese oxides supported on titania was prepared by sol-gel method and employed as SCR catalyst for simultaneous NO and mercury removal from coal combustion flue gas. The simultaneous NO and Hg 0 conversion rate on MnO x /TiO 2 was evaluated in different atmospheres, and the interaction between denitration and demercuration was investigated. The results indicated that MnO x /TiO 2 had good activity in simultaneously removing NO and Hg 0 in SCR atmosphere (NH 3 + NO + O 2 + N 2 ). However, both NO conversion and Hg 0 removal efficiency were inhibited in simulated coal combustion flue gas compared to that in SCR atmosphere because of the presence of SO 2 leading to the generation of sulfite and sulfate on the catalyst. H 2 O in simulated coal combustion flue gas had negative effect on the catalytic performance as well. NO conversion in oxy-fuel combustion flue gas was lower than that in air combustion flue gas, while Hg 0 removal efficiency in oxy-fuel combustion flue gas was higher than that in air combustion flue gas. Hg 0 displayed no obvious influence on NO conversion and N 2 selectivity over SCR process. And SCR atmosphere showed almost no inhibition to Hg 0 removal when the temperature was below 300 °C. At the optimal temperature for NO conversion (250 °C), the inhibition of SCR atmosphere on Hg 0 removal became stronger as the space velocity (GHSV) increased, but the inhibitive effect could be ignored when GHSV slowed down to 50,000 h − 1 or less.

Wet flue gas desulfurization (WFGD) systems have several benefits, including SO2 removal and Hg pollution control. However, the absorbed ionic mercury may be transformed into insoluble elemental mercury because of the chemical interaction with the aqueous scrubbing solution, which causes mercury re-emission and reduces the mercury capture efficiency of the scrubber. This study investigates the effects of operating temperatures, pH, and O2 and SO42 − concentrations on the reduction of Hg2 + in the presence of SO32 − in a simulated desulfurization aqueous solution. The results indicate that excess SO32 − inhibits Hg2 + reduction due to the formation of the stable Hg(SO3)22 − complex, whereas a low SO32 − concentration (< 2 mM) leads to enhanced mercury re-emission due to the formation of more redox-unstable HgSO3. The Hg0 release increases from 18.6% to 59.6% when the operating temperature increases from 45 °C to 55 °C. A pH decrease in the slurry from 5 to 3 causes a significant increase in the Hg0 emission from 6.9 to 127.9 μg/m3 in a simulated desulfurization slurry. In addition, O2 caused a secondary emission of Hg0 by damaging the stable redox complexes of Hg2 + and SO32 −. In the presence of oxygen, the Hg0 emission decreases; subsequently, a HgSO3SO42 − complex is formed. Sulfate (HgSO4 and HgSO3SO42 −) inhibit the emission of Hg0.

The emission and migration characteristics of Hg from an ultra low emission (ULE) coal-fired power plant in China was investigated. During the tests, the flue gas was sampled simultaneously at the inlet and outlet of selective catalytic reduction (SCR) system, low temperature economizer (LTE), electrostatic precipitators (ESP), wet flue gas desulfurization (WFGD), and wet electrostatic precipitators (WESP) by EPA 30B method. The feed coal, lime, limestone slurry, process water, fly ash, bottom ash, gypsum, FGD effluent, and WESP effluent were also sampled. The results showed that Hg concentration in flue gas at the outlet of boilers and stacks was in the range of 4.46–5.17 μg/m 3 and 0.51–1.22 μg/m 3 , respectively. The overall gaseous Hg removal efficiencies of SCR + LTE + ESP + WFGD + WESP equipped in the ULE power plant were about 88.5%–89.6%. Mass distribution of Hg in the whole system showed that about 70% of Hg present in solid and liquid combustion products and 30% of Hg emitted into atmosphere. After ULE reformation, the atmospheric emission factor of the power plant is in the range of 0.39–0.81 g/TJ, which is much lower that of power plants before ULE reformation (2.18–2.34 g/TJ). Thus, the ULE reformation for coal-fired plants is beneficial for the reduction of Hg emission to atmosphere.

In this study, the combustion and emission characteristics of slurry from an Indonesian lignite washery tailing (LWT) and a bituminous coal were studied and compared in both a bubbling fluidized bed (BFB) and a circulating fluidized bed (CFB). The effects of excess air ratio, feeding rate, secondary air ratio, and secondary air location on the flue gas emissions were analyzed to investigate the optimal operating conditions. The results show that it is feasible to directly fire LWT slurry in a CFB. The temperature of the dense-phase bed firing the LWT slurry can reach 800 °C but is lower than that of a normal BFB/CFB firing coal. Both SO2 and NO emissions of bituminous coal are higher than those of LWT slurry, but their emission characteristics are still below the limits for both EU and Chinese regulations. Improved emission characteristics are observed when firing LWT slurry and coal in CFB compared to BFB. Two main differences were found between LWT slurry and coal: (1) Low primary air (PA) flow rates fa...

The environmental problem concerning Hg pollution has received worldwide attention. Coal fired power plants are responsible for large amounts of Hg emission and produce abundant by-products in particular gypsum which is capable of extensive use. In this study, the migration of Hg in the gypsum production process and effluent treatment process in a typical wet flue gas desulfurization (WFGD) system was investigated and the temperature programmed decomposition technique was applied to identified Hg species in these products. Hg concentration in both the solid and liquid fraction of samples obtained in wet flue gas desulfurization system were determined by atomic fluorescence spectroscopy. The results indicated that gypsum accounted for a small proportion (29.9%) of Hg while the majority of Hg was transported to effluent treatment process where over 99.6% Hg was removed. The amount of Hg discharged from WFGD in the drainage, gypsum, and desulfurization sludge were 0.04 t/yr, 13.56 t/yr, and 9.56 t/yr, respectively. Desulfurization environment promoted HgS formation and lead to HgS being dominant in gypsum. The alkaline environment in the effluent treatment process contributed to the formation of HgO which was regarded as the primary Hg compound and accounted for 49.5%, 54.8%, and 78.5% of the total Hg in the neutralization tank, precipitation tank, and flocculation tank, respectively. The occurrence of HgCl2 in the solid fraction attributed to absorption of solid particles when it precipitated and was enhanced by the addition of chemicals. There was no obvious difference in the proportion of HgSO4 in the effluent treatment process. Systematic studies on difference in the partitioning of Hg species enables a better understanding on Hg behavior and provides conferences on targeting removal of Hg species in WFGD system.

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.

Coal water slurry (CWS) was prepared from lignite washery tailings. Its moisture content can be subdivided into two forms: free water (surface adsorption water) and bound water, i.e., interparticle, capillary, adhesion and internal adsorption water. The effect on moisture distribution of three distinct dispersants was studied through thermal drying and TG–DSC analysis. A new test method combining thermal drying and bond strength analysis was put forward for a thorough moisture distribution. The new method showed reasonable results and arrives at the same conclusion as the TG–DSC method. The addition of dispersants increased the free water content and decreased the bound water content, in particular those of interparticle and capillary water. Also there was a slight decrease in total moisture, compared to CWS prepared without dispersant. The moisture distribution showed its biggest change with dispersant CLS (calcium lignosulfonate), followed by dispersant NDF (a co-polymer of methylene naphthalene sulfonate, styrene sulfonate and maleate), and ended up with NNO (sodium methylene bis-naphthalene sulfonate).

The safe and stable operation of the power system has always been a common problem related to social stability and economic development in the world. To adapt to the development of “Internet +" and energy Internet, to ensure the information security of the power industrial control side, the power industrial control system Information security raises higher requirements. First, the ICS communication model is abstracted, the security risks and threats faced by ICS are sorted out, the most urgent and critical security requirements are clarified, and then a communication enhancement scheme is designed without affecting functions, efficiency, and rapid deployment. This includes one-way authentication and integrity checking of critical communication messages, combined with a timestamp mechanism and registration mechanism. Finally, through the security analysis of the enhanced scheme, it proves that it can resist common attacks such as camouflage, tampering and replay.

Industrial control system is widely used in social production activities and its security is directly related to national security and social stability. In this paper, the security threats and protection status of power industry control system are analyzed. A framework of information security evaluation system for power industry control system is proposed, which consists of three parts: experimental verification environment, product detection capability and security service capability, and the construction scheme of the system is discussed. A hardware-in-the-loop simulation and verification platform is constructed to realize the simulation and verification of power industry control system tools. The vulnerability of power industry control protocol can be found in depth. The problem of ambiguous attack mechanism and lack of verification means of power industry control system is discussed, which can provide support for the research of attack and protection of power industry control system.

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

Highly monodisperse hybrid spherical silica nanoparticles with diameters ranging from 30 to 200 nm were prepared by a one-step emulsion polymerization in aqueous solution. In contrast with the former method for preparing the hybrid silica materials, our method has three advantages. (1) Through this one-pot route, hybrid silica particles with organic functional groups on the surface are prepared in aqueous solution. (2) The particles are created in a size range of 30-200 nm and highly monodisperse. (3) The size of the particles can be effectively well-defined and precisely controlled depending upon the synthesis conditions such as the concentration of surfactant. Other kinds of organosilane monomers have also been tried in the same way. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were performed to elucidate the morphologies of the hybrid silica particles. Thermogravimetric analysis (TGA), (29)Si NMR, and (13)C NMR were used to gain information about thermal properties and detail structure. This approach may open a new broad avenue for the hybrid material in the field of photocrystal, electronic enveloping.

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.

A series of thermo-sensitive polyurethane-NIPAAm hydrogel membranes with various cross-linking densities have been obtained by the UV-curable method. Sucrose, β-cyclodextrin and dextran were used as the model compounds to evaluate the solute permeability through the hydrogel membranes. The solute permeability depends on the solute size, the hydration and the cross-link density of the hydrogel. Sucrose permeability has been found following the free-volume theory but with different permeating behaviors between the high- and low-hydration hydrogels. The water structure in the hydrogel has been analyzed by the DSC method. It has been found that the high-hydration hydrogels contain relatively more freezing water, while the low-hydration hydrogels are occupied mainly by the nonfreezing bound water. The different water structures between the high- and low-hydration hydrogels are considered to be responsible for their discrepancy in the permeability.

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.

The solution properties of hydroxyl terminated hyperbranched aliphatic polyesters and their acetyl derivatives have been studied by measuring viscosity parameters. The polarity of terminated groups of molecules is the most important factor affecting their properties. The intrinsic viscosity [η] cannot reflect the real monomolecular hydrodynamic volume of hydroxyl group-terminated hyperbranched polymer due to the strong intermolecular forces which lead to the formation of stable clusters. The intermolecular association constant KM depends not only on molecular weight, but also on the polarity of end-groups. However, the dynamic contact concentration CS can be determined accurately from reduced viscosity versus concentration plots. The reason why the intrinsic viscosity does not change linearly with the generation of the hyperbranched aliphatic polyesters is explained using ‘free-draining’ and ‘non-draining’ models. © 2001 Society of Chemical Industry

Plasma polymerization of hexamethyldisiloxane(HMDSO) in the presence of different carrier gases such as H2, He, N2, Ar, and O2 was carried out using an inductively coupled electrodeless glow discharge. The polymerization kinetics showed that the monomer HMDSO plasma-polymerized at different rates from low to high for the carrier gases H2, He, N2, Ar, and O2 in that order. The products were studied using FTIR, electron spectroscopy for chemical analysis, and elemental analysis. The results indicated that HMDSO molecules underwent different degrees of fragmentation in plasma polymerization for different carrier gases and radio frequency (RF) powers. The polymer deposition rate and the structures of products were mainly dependent on molecular fragmentation, which varied with carrier gas and imposed RF power. O2 and H2 gases can incorporate in the plasma polymers to form products containing more oxygen or hydrogen components, while other gases such as N2 have no detectable component in products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1434–1438, 2001

Polyanhydrides from cycloaliphatic 1,4-Cyclohexanedicarboxylic acid (1,4-CHDA) were synthesized by melt polycondensation and characterized by WAXD, FTIR and DSC. The results show that these polymer displayed strong crystallinity with highly melting point and can't be dissolved in common solvents. The polymers, which come from different original isomer conformation CHDA, show different melting point and DSC curve. The isomerization happened during the polymerization and reached an equilibrium point at last. By melt polycondensation, the high cis-isomer content polyanhydride is difficult to obtained.

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

A polyurethane ionomer with a specific ionic structure was synthesized in an attempt to induce ionic aggregate dissociation at elevated, but observable temperatures. By means of hot-stage wide-angle x-ray diffraction (WAXD), the dissociation could be clearly detected before the onset of degradation.

A nematic liquid crystalline polymalonate has been synthesized by melt polycondensation of a nonlinear optical (NLO) monomer and a liquid crystalline (LC) monomer. The polymer was characterized by VPO, FTIR, DSC, WAXD, UV-visible spectroscopy and polarized optical microscopy. The LC temperature interval was found between 398 K and 420 K by DSC. Some interactions originated from the attachment of the side groups to the polymer backbone were detected by UV-vis spectroscopy.

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.

The polyether-ester polyamic acid imidization process in a solid state was studied by microwave radiation. The imidization content at different radiation times was calculated quantitatively by FTIR and was confirmed by the results of dynamic mechanical analysis (DMA). The microwave radiation imidization may drop the reaction temperature and cut the reaction time down in comparison with the thermal imidization. It may be expected theoretically that the microwave radiation may generally be suitable for the condensation polymerization reaction and facilitates the reaction, especially at its later stage.

Polyurethane elastomers pendant with azo-dye were prepared by N-substitution by a two-step process. First, the polymer is metalated by sodium hydride, and then the prepared urethane polyanion is treated with ω-bromohexyloxyphenyl-p-nitroazobenzene. The polyurethanes were characterized by NMR, UV, FTIR, GPC, DMA, X-ray, and polarized optical microscopy. The reaction caused cleavage of some allophanate bond degradation and narrower MW distribution. As the substitution degree increased, the hydrogen bonds in polyurethane diminished and phase mixing with azo-dye was enhanced. Photoisomerization of the pendant azo-dye was also observed. © 1996 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.

By the method of the absolute quantitative SEC, a process of anionic oligomerization of styrene, initiated by n-butyl lithium, was followed. The concentration of 1–5-mer monodisperse species in different reaction times can be obtained by HPSEC separation. The results showed that the propagation rate constants increased with increasing chain length and converged to a constant. © 1996 John Wiley & Sons, Inc.