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Doping and increasing specific surface area by forming highly porous structures are two effective ways to enhance the photocatalytic performances of TiO2 particles. Here for the first time, we report a new facile method to prepare the macroporous-mesoporous C-, S-, N-doped TiO2 (C/S/N-TiO2) microspheres via polyHIPE microspheres as templates. The chemical and crystalline structures of these hierarchical porous TiO2 microspheres are analyzed with FTIR, XPS, EDS, and XRD. The macroporous-mesoporous structures are confirmed with SEM observation and BET analysis. UV–vis DRS spectra analysis shows that the band gaps of C doped TiO2, C/N doped TiO2, C/S doped TiO2 and C/S/N doped TiO2 are estimated to be 3.07, 3.01, 2.94 and 2.81 eV, respectively, which are significantly narrower than that of TiO2 nanoparticles (3.23 eV). Photoluminescence spectra demonstrate that the recombination of electrons and holes in these macroporous-mesoporous TiO2 microspheres is also suppressed. The hierarchical porous C/S/N-TiO2 microspheres show high visible-light catalytic efficiency and excellent cycling stability to degrade RhB dye.

A large amount of oily cuttings is produced in the drilling process when the oil-based drilling fluid is used. The oil and oil-soluble additives adsorbed on the surface of the cuttings may pollute the environment. In this paper the method of silicic acid precipitation and formation of silicic acid micromicelles is used to encapsulate oil and to remove oil from the cuttings. The authors analyze the influence of the stirring time and the solution pH on the oil removal efficiency. When the pH is 2 and the stirring time is 10 min, the oil removal rate is 96%. Research into the mechanism shows the successive formation of silicic acid sol and gel in the process of silicic acid precipitation. The structure of the silicic acid micromicelles is characterized by scanning electron microscopy (SEA). The results of differential scanning calorimetry (DSC) indicate the existence of the exothermic decomposition peak of the hydrocarbons in the range from 350°C to 500°C, which proves that the micromicelle inner phase contains oil.

Here, we designed several waterborne polyurethanes (WPUs) with efficient thermally activated delayed fluorescence (TADF) via serving charge-transfer (CT) states as a mediate bridge between singlet and triplet states to boost reverse intersystem crossing (RISC). By tuning substituents of diphenyl sulfone (DS), we found that O,O'- and S,S'-substituted DS covalently incorporated in WPUs solely show typical fluorescence emission with lifetimes in the nanosecond range. Interestingly, TADF appears by replacing the substituent with the nitrogen atom, of which lifetimes are up to ≈10 microseconds and ≈1 millisecond in air and vacuum, respectively, even though the energy gap between singlet and triplet states (ΔEST ) is still large for generating TADF. To explain this phenomenon, an energy level mode based on CT states and an 3 (n-π*) receiver state was proposed. By the rational modulation of CT states, it is possible to tune the ΔEST to render TADF-based materials suitable for versatile applications.

The three-dimensional (3D)-printing of hydrogels with excellent mechanical properties has attracted extensive attention owing to their potential applications in many fields. Through the photoinitiated copolymerization of methacrylic acid (MAAc) and N-(pyridin-2-yl)acrylamide (NPAM) in dimethylsulfoxide (DMSO), a copolymer solution was prepared; it was then 3D printed at 70 °C followed by solvent replacement of DMSO with water at 25 °C, and a novel 3D-printed tough hydrogel was prepared. In the presence of water, NPAM could undergo “multi-fold” hydrogen bonding with MAAc. Thus, the hydrogen bonding is strengthened and stabilized by the hydrophobic α-methyl of MAAc and the pyridine N-heterocycle of NPAM, meaning that the modules of the hydrogel can be up to five times stronger than the original organogels. The swelling or shrinkage of the gel is negligible during solvent replacement and the resultant hydrogel exhibits excellent mechanical properties, with an elastic modulus of 1.8–66 MPa, a tensile fracture stress of 2.2–6.3 MPa, a fracture strain of 360–570% and a fracture energy of 0.5–7.2 kJ m−2. In addition, owing to the dynamic nature and temperature sensitivity of the hydrogen bonds, the hydrogel also exhibited fast self-recovery abilities and temperature activated shape memory properties. In particular, the hydrogen-bonding hydrogel could be quickly degraded and recovered by adjusting the pH, which allowed convenient recycling of the hydrogels. Our experimental results indicated that the combination of a 3D-printing technique and solvent replacement may provide a novel and effective method to obtain 3D-printed hydrogels with high mechanical strength and shape recovery properties, fostering their use in a number of fields such as soft robots, implant devices, tissue engineering and other environment friendly materials.

Room-temperature phosphorescent (RTP) materials have been widely used in sensing, imaging and display technology. The ability to predict and modulate RTP properties, such as emission color and lifetime, is particularly important for the design of rational materials. Here, we show that by incorporating three different types of acceptor moieties into a polylactide (PLA)-substituted carbazole donor, RTP with different emission colors and lifetimes (with an absolute quantum yield of up to 39.4%) could be generated. Specifically, the chemical conjugation between an n–π* type of luminophore and a π–π* one most likely results in dual RTP while the conjugation between two π–π* types of luminophores produces fluorescence-RTP (F-RTP) dual emission. The consistency between the experimental results and theoretical calculations further validates the observation. To demonstrate the versatility and application potential of these purely organic, biocompatible materials, aqueous nanoparticles were fabricated and used as high-contrast cell imaging agents, given the large Stokes shift of RTP materials.

Metal coordination hydrogels have drawn intensive attention in controlled drug release due to their facile incorporation of stimuli and dynamic self-healing properties. However, many metal coordination hydrogels which are responsive to mild physiologically relevant stimuli are restricted by their poor stability in non-triggering environments. Here, we reported a new strategy for enhancing the neutral stability of a pH-responsive self-healing hydrogel based on multivalent metal coordination without loss of its responsiveness. The hydrogel was formed by multivalent coordination of Ni2+ with polyhistidine (PHis) and multiple iminodiacetic acid (IDA) ligands which were modified on the terminal groups of polyethylene glycol (PEG) and the side groups of oligochitosan (OChi), respectively. By incorporating multivalent coordination, the hydrogel maintains its self-healing character and weak acid responsiveness; it can also be used as an injectable hydrogel by injecting it into a neutral environment. Through varying the PHis : IDA ratio, the mechanical strength and dynamic relaxation of the hydrogel can be regulated conveniently. More importantly, the hydrogels with multivalent coordination can remain stable and integral in neutral buffer (pH 7.4); meanwhile, they dissolve quickly in a weak acid environment (pH 5.5), which is similar to some tissue disease conditions. In contrast, the control hydrogel without multivalent coordination disintegrated within 4 hours in the neutral non-triggering buffer. Because the hydrogel consists of large amounts of coordinative Ni2+ ions, it naturally possesses relatively high affinity to molecules containing polyhistidine motifs. Thus, pH-tuned controlled release of a model molecule, rhodamine-modified polyhistidine, was accomplished, with limited neutral leakage and quick release in weak acid. These results indicate potential applications for this multivalent coordination hydrogel in the controlled release field.

As one of the most promising biomaterials, injectable self-healing hydrogels have found broad applications in a number of fields such as local drug delivery. However, controlled release of drugs in hydrogels is still difficult to realize up to now. Here, we report a novel photo-degradable injectable self-healing hydrogel based on the hydrophobic interaction of a biocompatible four-arms star polymer, poly(ethylene glycol)-b-poly(γ-o-nitrobenzyl-l-glutamate). The hydrophobic interaction between poly(γ-o-nitrobenzyl-l-glutamate) not only connects poly(ethylene glycol)-b-poly(γ-o-nitrobenzyl-l-glutamate) together with a crosslink but also provides a hydrophobic domain to encapsulate hydrophobic pharmaceuticals such as doxorubicin (DOX). Due to the dynamic character of the hydrophobic interaction, the hydrogel exhibits excellent injectable and self-healing ability. In particular, the photolabile o-nitribenzyl ester group is cleaved under UV irradiation. As a result, the hydrophobic domain transforms into the hydrophilic one and the embedded DOX is released effectively. An increasing release ratio of DOX dramatically enhances the apoptosis ratio of HeLa cells. We expect these attractive properties may be beneficial to practical applications of the hydrogel as an effective local drug delivery means in a truly physiological environment.

The rational construction of carbon materials with well-designed porosity and appropriate surface functionality is of critical significance for high-performance supercapacitors. Herein, we report a design strategy for the facile synthesis of N/S-co-doped carbon nanobowls through a one-pot condensation and carbonization process. The carbon nanostructure can be changed from a nanoball to a nanobowl by elaborately controlling the capillary compression and nanoshell thickness. The N/S-co-doped carbon nanobowls greatly increase the volumetric density by eliminating hollow interiors. The unique hierarchical micro/mesoporosity and the N,S-functionalized structure enable the carbon nanobowls to utilize the high specific surface area efficiently resulting in high specific capacitance and ultrafast charge/discharge capability. The electrochemical benefits endow the symmetric supercapacitors with a high energy density of 9.6 W h kg−1, a maximum power density of 475.5 kW kg−1, and a long cycle lifetime over 50 000 cycles. These encouraging results demonstrate the potential of the N/S-co-doped carbon nanobowls for application in ultrahigh-power supercapacitors.

Lithium-sulfur (Li-S) batteries represent an attractive energy storage technology for the employment in next-generation high-energy–density rechargeable batteries. The main challenge is to increase the electrochemical utilization and stabilization of sulfur cathodes by mitigating the undesirable soluble polysulfide shuttle problem. Herein, a zinc selenide/carbon hybrid (ZnSe/C) is constructed as a regulator of commercial polypropylene (PP) separator to modify the sulfiphilicity of polysulfide species. It is revealed that the polar ZnSe/C hybrid greatly inhibits the shuttling effect by strong chemisorption and thereafter fast electrocatalytic transformation of polysulfides. Accordingly, the ZnSe/C-modified PP separator could kinetically expedite the redox reaction and effectively promotes the utilization and confinement of the active sulfur in the cathode side. As a consequence, the ZnSe/C-PP-cell exhibits excellent electrochemical properties, including an impressive capacity delivery of 1458/605 mAh g−1 at 0.1 C/5 C and long lifetime with 608 mAh g−1 retained after 1000 cycles at 1 C. This study paves a rational pathway for designing and propelling transition-metal-selenide electrocatalysts toward the practical application of Li-S batteries.

Injectable self-healing hydrogels have found broad applications in drug delivery, tissue engineering and controlled 3D cell culture. Recently, cyclic disulfides were found to be useful in cross-linking and stabilizing liposomes by disulfide exchange polymerization, benefiting from the enhanced reactivity of the disulfide bonds. Herein, we report an injectable self-healing hydrogel constructed from cross-linked F127 with thermo and pH dual responsivity. The rapid sol-gel transition ability at body temperature allows it to be used as an injectable hydrogel. And the increased reactivity of the disulfides of cyclic dithiolane due to the ring tension makes the hydrogel self-heal under not only alkaline conditions but also neutral or even mildly acidic conditions.

Novel waterborne polyurethane (WPU) with side-chained Phenylazonaphthalene group was prepared by step-growth addition polymerization between isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMG), 2, 2-dimethylol propionic acid (DMPA) and a self-made azo diol, N,N-(2-hydroxyethyl)-4-phenylazo naphthylamine (HPN), as a chain extender to partially substitute for 1, 4-butanediol (BDO). 1H nuclear magnetic resonance spectra (1H NMR), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet–Visible (UV–Vis) spectroscopy were used to research the properties of HPN and HPN-WPU. The WPU latex presented obvious trans–cis photoisomerization during UV radiation and the absorption wavelength of the HPN exhibited a blue shift after attached into polyurethane chains. It needed longer irradiated time to finish isomerization due to the emulsion aggregated states, comparing with phenylazonaphthalene monomer solution and WPU dilute solution.

Molecularly imprinted polymers (MIPs) prepared using conventional functional monomers exhibit poor specific extraction of scopolamine from tropane alkaloids, which hinders their application in separation and purification. In this paper, a novel molecularly imprinted polymer (MIP) was prepared by precipitation polymerization using scopolamine as the template, monoethyl fumarate (MFMA) as a functional monomer, and ethylene dimethacrylate (EGDMA) as a cross-linker. The advantages of the supercritical fluid technology for the removal of the template were verified by comparing the efficiency of the swelling method and the Soxhlet extraction method. The prepared MFMA-based MIPs (MFMA-MIPs) showed a high adsorption capacity (49.75 mg g−1) and high selectivity toward scopolamine with a selectivity coefficient of 3.5. 1H NMR spectroscopy was performed to demonstrate the interactions between the two functional groups of the functional monomer and the template. Lastly, MFMA-MIPs were used as solid phase extraction (SPE) sorbents for scopolamine analysis. It was found that 97.0–107.0% of the template had been extracted using the SPE column from the complex of scopolamine, atropine and anisodamine. The mean recoveries of scopolamine from plant samples were 96.0–106.0% using the established method, which showed a good linearity in the range of 8.0–4.0 × 104 μg L−1. The results showed that MFMA-MIPs could be applied for the separation of scopolamine from tropane alkaloids.

Two types of naphthalimide derivatives were synthesized by introducing a carbazole group and an n-butyl, respectively, into the naphthalimide system. The electron-donating ability of two kinds of derivatives was investigated by the electrochemical method. These two types of derivatives were used as initiators for the polymerization of d and l-lactide polymerization. Here, the emission and UV-vis absorption serve as the main focus. Compared with solely donor-initiated polylactide (PLA), the PLA with a donor-acceptor structure has a more efficient phosphorescence emission, of which the longest phosphorescence lifetime is up to 407 ms. The experimental results reveal the existence of charge-transfer states in the donor-acceptor-ended polymer. Due to the role of charge-transfer states, a red phosphorescent polymer was developed. Theoretically, these desirable advantages render synthesized PLAs a potential candidate for bioimaging and anti-counterfeiting.

Smart materials responsible to external stimuli such as temperature, pH, solvents, light, redox agents, and mechanical or electric/magnetic field, have drawn considerable attention recently. Herein, we described a novel rhodamine (Rh) mechanophore-based mechanoresponsive micellar hydrogel with excellent mechanochromic and mechanofluorescent properties. We found with astonishment that, due to the favorable activation of rhodamine spirolactam in the presence of water, together with the stress concentration effect, the mechanoresponsive sensitivity of this hydrogel was enhanced significantly. As a result, the stress needed to trigger the mechanochromic property of Rh in the hydrogel was much lower than in its native polymer matrix reported before. The hydrogel based on Rh, therefore, exhibited excellent mechanochromic property even at lower stress. Moreover, due to the reversibility of color on/off, the hydrogel based on Rh could be used as a reusable and erasable material for color printing/writing. Of peculiar importance is that the hydrogel could emit highly bright fluorescence under sufficient stress or strain. This suggested that the stress/strain of hydrogel could be detected quantificationally and effectively by the fluorescence data. We also found that the hydrogel could respond to acid/alkali and exhibited outstanding properties of acidichromism and acidifluorochromism. Up to now, hydrogels with such excellent mechanochromic and mechanofluorescent properties have rarely been reported. Our efforts may be essentially beneficial to the design of the mechanochromic and mechanofluorescent hydrogels with enhanced mechanoresponsive sensitivity, fostering their potential applications in a number of fields such as damage or stress/strain detection.

A series of novel waterborne polyurethane dispersions (HPB-WPU) possessing the property of photochromism was prepared from isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMG), and 2, 2-dimethylol propionic acid (DMPA) using a self-made azo diol, N, N-bis-(2-hydroxy-ethyl)-4-phenylazo-aniline (HPB), as a chain extender to partially substitute for 1, 4-butanediol (BDO). The molecular structures of HPB and HPB-WPU were confirmed using Fourier-transform infrared spectroscopy. The photochromism of HPB and HPB-WPU was evaluated using ultraviolet visible (UV-Vis) absorption spectroscopy during the test. The results indicated that when the dispersion was placed under UV irradiation, the color and absorption intensity both changed. The UV-Vis absorption showed a blue shift effect of about 33 nm when HPB was blocked into polyurethane chains. The azo chromophore became permanently fixed into the molecule, and the dispersions remained stable for a long time because of the covalent bonding with poly...

In this study, a novel photo- and pH-sensitive cationic waterborne polyurethane containing side chain aromatic azo groups (Azo-CWPU) was synthesized by step-growth addition polymerization from polyether polylol, isophorone diisocyanate, N-methyl diethanolamine and a new aromatic azo-containing monomer, 2,2′-(4-((4-ethylphenyl)diazenyl)phenylazanediyl)diethanol (EDPD). Azo-CWPU showed a significant hypsochromic contrast to the azo monomer and rapid changes in UV–Vis absorption spectra at different irradiation times. Azo-CWPU dispersion displays bright yellow, orange and red color with the change of pH values. Regarding the orange dispersion, we assume that there is a mixture of the azoic form and the hydrazone form. Compared to cationic waterborne polyurethane dispersion without aromatic azo groups (CWPU), Azo-CWPU dispersion with smaller hydrodynamics radius and more narrow distribution shows good thermodynamic properties of polyurethane.

Hierarchically porous carbon nanomaterials with well-defined architecture can afford a promising platform for effectively addressing energy and environmental concerns. Herein, a totally green and straightforward synthesis strategy for the fabrication of hierarchically porous carbon nanotubes (HPCNTs) by a simple carbonization treatment without any assistance of soft/hard templates and activation procedures is demonstrated. A high specific surface area of 1419 m2 g-1 and hierarchical micro-/meso-/macroporosity can be achieved for the HPCNTs. The unique porous architecture enables the HPCNTs serving as excellent electrode/host materials for high-performance supercapacitors and Li-sulfur batteries. The design strategy may pave a new avenue for the rational synthesis of hierarchically porous carbon nanostructures for high-efficient energy storage applications.

Fluorescent and room-temperature phosphorescent (RTP) materials are widely used in bioimaging, chemical sensing, optoelectronics and encryption. Here, a series of single-component dual-emissive waterborne polyurethanes (WPUs) with both fluorescence and room-temperature phosphorescence were synthesized. Dye without halogen atom incorporated into WPUs can only exhibit fluorescence due to poor spin-orbit coupling. When bromine atom is introduced into dye, we found that WPUs can emit both fluorescence and room-temperature phosphorescence with lifetimes up to milliseconds because of enhanced spin-orbit coupling. Moreover, with an increase in dye concentrations in WPUs, excimers are formed due to the aggregation effect, and may promote communication between singlet and triplet states. At different dye concentrations, structural, thermal, and luminescent properties serve as the main focus.

A new class of smart structural hydrogels is prepared by introducing dual cross-linkers into a single-network system. The present hydrogel, on the one hand, exhibits excellent mechanical properties; on the other hand, it exhibits thermally induced plasticity and a shape memory effect without any overlap.

The relaxation processes of α-form nylon 1212 from 50°C up to 160°C were studied by dielectric relaxation spectroscopy (DRS) in a wide frequency range of 63 Hz to 5 MHz. The α relaxation, the electrode relaxation, and the conductivity relaxation of nylon 1212 were observed and analyzed in detail using permittivity and modulus formalism. Electrode polarization and dc conductivity were the origin of high dielectric permittivity values at low frequencies and high temperatures. The strength of the imaginary part of the electric modulus of conductivity relaxation M″ max was nearly independent of temperature. The distribution of local conductivity and relaxation time became broader with decreasing temperature.

A novel anionic waterborne polyurethane-based fluorescent dye WPU-DV26 was synthesized by incorporating the molecular structure of disperse violet 26 (DV26) into the polyurethane chain. The structure of WPU-DV26 was confirmed by means of Fourier transform infrared spectroscopy and UV–vis absorption analysis. Comparing to the UV–vis spectrum of DV26, WPU-DV26 showed a hypsochromic shift from the absorption maxima of 518, 558, 609 nm to 510, 548, 586 nm, respectively. WPU-DV26 can form stable latex in water. The number average molecular weight and its distribution index, and average latex particle size for WPU-DV26 were determined to be 2.33×10 4 , 1.36 and 80 nm, respectively. The improved thermal stability of WPU-DV26 can be attributed to the embedded anthraquinone unit of DV26. It was found that both the intensity and stability of the fluorescence of WPU-DV26 latex were improved significantly compared with those of DV26.

Poly[methyl methacrylate(81)/butyl acrylate(19)] copolymer was exposed to atmosphere of humidity for various times. The normal α and ρ peak, a third LL peak is observed in thermally stimulated depolarization current (TSDC) spectra of the copolymer. The α peak corresponds to the glass transition, the ρ peak originates from the detrapping of trapped carriers in the bulk amorphous structure, and the LL peak can be attributed to the charge detrapping related to the liquid–liquid transition of the copolymer. The three peaks all move to lower temperature with an increase of the moisture content, indicating that the flexible moisture content not only has an effect of plasticization on the glass transition and liquid–liquid transition, but also makes the trap depth of ρ peak shallower. The trap depth of ρ peak is affected by the introduction of moisture content and the degree of hydration of the copolymer. Based on analysis of calculated results, it was confirmed that the relaxation time of LL peak obeys VF equation when temperature is below T LL.

Using the blend of methyl methacrylate (MMA) and butyl acrylate (BA) instead of acetone as a diluent, hydroxyethyl acrylate to terminate the ends of prepolymer, and emulsifying at 85°C, TDI-polyurethane/polyacrylate (TDI-PU/PA) composite emulsion was prepared using toluene diisocyanate (TDI), polypropylene glycol (PPG), 1,6-hexanediol (HDO) and dimethylol propionic acid (DMPA) on the basis of solvent-free method. The chain structure and polymerization progress were confirmed by the analysis of Fourier transform infrared spectroscopy. The desired emulsion could be synthesized when the molar ratio of NCO group in TDI to total OH groups in PPG, DMPA and HDO was 1.18, triethylamine (TEA) and water were added simultaneously during the emulsification, and acrylic monomers were initiated by potassium persulfate at 80°C. It was found that tensile strength, pendulum hardness of the latex film cast from composite emulsion increased and water resistance became better with increasing the content of MMA. Compared with...

A novel yellow fluorescent diisocyanate 3,6-di(hexamethylene urethano)spiro[xanthene-9,3′-phthalide] diisocyanate (DIX) was synthesized by the reaction of fluorescein with hexamethylene diisocyanate first. Using DIX to substitute partially isophorone diisocyanate (IPDI), a kind of yellow fluorescent waterborne polyurethane DIX-WPU was prepared by blocking the fluorophore of DIX into the polyurethane chain using IPDI, polytetramethylene ether glycol and 2,2-dimethylol propionic acid. The molecular structure of DIX and DIX-WPU was confirmed by means of Fourier transform infrared spectroscopy. The fluorophore is fixed permanently in the polyurethane chain and is difficult to migrate due to the covalent bonding with other component during the synthesis. The fluorescence intensity of DIX-WPU fluorescent dispersion was enhanced greatly comparing with that of fluorescein in a wide range of fluorophore content between 1 × 10–7 and 1 × 10–3 mol/L. The fluorescence of DIX-WPU dispersion is very stable not only for ...

Nonisothermal crystallization behavior of poly(butylene terephthalate) (PBT) was investigated by means of differential scanning calorimetry. The nonisothermal crystallization kinetic process was analyzed and relative kinetic parameters were obtained with the Avrami and Liu–Mo equations. The results demonstrate a heterogeneous nucleation mechanism. It was found that the nonisothermal primary crystallization of PBT was composed of two courses. Course I corresponded to the two-dimensional formation process of the lamellae, and the corresponding relative crystallinity (Xt) was less than 15%. Course II was concerned with the three-dimensional growth process of the spherulite, and Xt changed from 15 to 90%. The secondary crystallization began when Xt was greater than 90%. According to the Flynn–Wall–Ozawa equation, the activation energies for course I, course II, and secondary crystallization were calculated to be −120, −210, and −100 kJ/mol, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A novel fluorescent aqueous polyurethane emulsion DDAQ-TDI-PU was synthesized by blocking the anthraquinone moiety of 1,4-diamino-2,3-diphenoxyanthraquinone (DDAQ) into polyurethane chain using 2,4-tolylene diisocyanate (TDI), poly(propylene glycol) and 2,2-dimethylol propionic acid. The chain structure of DDAQ-TDI-PU was confirmed by means of Fourier transform infrared spectroscopy and UV–vis analysis. Comparing to the UV–vis spectrum of DDAQ, DDAQ-TDI-PU showed a hypsochromic shift from the absorption maxima of 518, 558, 609 nm to 510, 548, 586 nm, respectively. It was found that the fluorescence intensity of DDAQ-TDI-PU emulsion was enhanced greatly comparing with that of DDAQ. The fluorescence of DDAQ-TDI-PU was very stable not only for the long term storage but also for the fluorescence quencher.

CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, P.R. ChinaReceived August 10, 2011, Accepted December 5, 2011Key Words : Polysulfone, Bergenin, Molecularly imprinted composite membranes, Supercritical CO

Thermally stimulated depolarization current (TSDC) experiments were carried out to investigate the effect of polarization temperature (T p) on liquid–liquid transition and space charge detrapping behavior in atactic polystyrene. Differential scanning calorimetry (DSC) measurement was applied as a complementary method. When T p is 130 °C, there are four distinct peaks (α, ρ1, LL, and ρ2) showed in TSDC spectrum in the range of 30–200 °C. Compared with the result of DSC, TSDC spectrum show that peak α corresponds to glass transition, peak LL is related to liquid–liquid transition, and peak ρ1 and peak ρ2 belong to the space charge current peak. As T p increases from 100 to 150 °C, the intensity of peak LL maximum increases and that of space charge peaks maxima decreases, which is attributed to different mechanism between liquid–liquid transition and space charge detrapping behavior. In addition, their corresponding characteristic parameters versus T p are also analyzed in detail.

Fluorescent brightening agent VBL-based waterborne polyurethane dye (VBL–WPU) was synthesized by incorporation of VBL into waterborne polyurethane chains. The expected structure of polymeric fluorescent brightening agent was confirmed by FT-IR and UV–vis spectra. The molecular weight, average particle sizes and the contents of VBL segments in VBL–WPU were investigated. This polymeric dye exhibited intriguing optical behaviors. The absorption and emission maxima of VBL–WPU showed obviously hypsochromic shift in comparison with those of VBL. The fluorescence intensity of the polymer was prominently enhanced comparing with VBL because of the changes of micro-circumstance of VBL. Furthermore, the fluorescence of VBL–WPU was not sensitive to hydroquinone quencher.

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical (). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of from to and pressure of 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

The effect of polarization temperature on the chain segment motion and charge trapping and detrapping in polyamide 610 films has been investigated by means of thermally stimulated depolarization current (TSDC) and wide-angle X-ray diffraction (WAXD). A small part of the amorphous phase of quenched polyamide 610 changes into the crystalline state with increasing polarization temperature. There are three current peaks (named α, ρ1, and ρ2 peak, respectively) in the TSDC spectra. The α peak corresponds to the glass transition, the ρ 1 peak is attributed to space charge trapped in the amorphous phase, and interphase between crystalline and amorphous phases, and the ρ 2 peak originates from space charge trapped in the crystalline phase. By analyzing the characteristic parameters of these peaks, it was found that the increase of polarization temperature induced a decrease of the chain segment mobility and promoted the creation of structural traps in polyamide 610. The decrease of the chain segment mobility in t...

The discharging process of polyvinyl pyrrolidone electret under two different heating rates 3.5 and 2 °C/min has been investigated by the measurement of thermally stimulated depolarization current (TSDC) in the temperature range from 30 to 250 °C. The TSDC spectra of PVP shows three peaks located at 70 ± 10, 150 ± 10, and 230 ± 10 °C, respectively. When explaining the TSDC spectra, this thesis deduced that the first peak, β peak, originates from side group relaxation; the second peak, α peak, corresponds to the relaxation of the frozen dipoles on the molecule chain segments during glass transition; the third peak, ρ peak, is attributed to the detrapping of the trapped space charge under thermal stimulation. The current of the ρ peak is remarkably strong due to the fact that PVP molecules’ side groups—the pyrrolidone rings containing lactam structure—are strong polar groups which cause the great increase in the number of bulk traps, trapped space charge, as well as detrapped space charge under thermal stimulation.

Based on the solvent-free method, novel fluorinated polyurethane/polyacrylate hybrid emulsions, dodecafluoroheptyl methacrylate (DFMA) as fluorinated monomer, were successfully prepared via emulsion polymerization without traditional emulsifier. For the purpose of increasing the grafting ratio of polyurethane and polyacrylate, 60Co γ-ray radiation polymerization had been adopted to enhance the hardness of latex film. The chain structure and polymerization progress were confirmed by the analysis of Fourier transform infrared spectroscopy. The grafting ratio of polymethyl methacrylate and polyurethane was obtained by calculating the ratio of N–H peak integral area and Ph(C=C) peak integral area. The effect of DFMA content on thermal stability, mechanical property and water resistance were investigated systematically by thermal weight loss analysis, tensile strength test, absorbed water ratio and water contact angle.

Fluorinated poly(ethylene oxide) propyl-b-polydimethylsiloxane-b-propyl fluorinated poly(ethylene oxide) (FPEO-b-PDMS-b-FPEO) was synthesized by a free radical addition of carbon–hydrogen of polyether segments of poly(ethylene oxide) propyl-b-polydimethylsiloxane-b-propyl poly(ethylene oxide) (PEO-b-PDMS-b-PEO) to hexafluoropropylene (HFP) using tert-butyl peroxypivalate as an initiator. In order to reduce the possibility of side reaction, the protection and deprotection via silylation were used for the end-hydroxyls in PEO-b-PDMS-b-PEO chain. The structure of Intermediates and FPEO-b-PDMS-b-FPEO was confirmed by means of Fourier transform infrared and 1H NMR spectroscopy. The effects of amount of initiator, reaction temperature and time on free radical addition were investigated in detail.

Novel fluorinated polyurethanes (FPU) with fluorine-containing pendent groups were synthesized from fluorinated polyether glycol (PTMG-g-HFP), 1, 6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) and 1, 4-butanodiol (BDO). The structure of the fluorinated polyurethanes was confirmed by the use of Fourier transform infrared spectroscopy (FTIR). The relation between surface components and structure of the fluorinated polyurethanes was investigated by X-ray photoelectron spectroscopy (XPS), contact angle and water resistance measurements. The results from XPS and contact angle studies indicated that the surface of fluorinated polyurethanes was significantly enriched with fluorine groups. The water resistance of polyurethanes was evidently improved by introducing fluorinated groups into PU.

A novel fluorinated polyurethane (FPU) with fluorine-containing pendent groups was prepared by using fluorinated polyether glycol (PTMG-g-HFP) as a soft segment, 1,6-hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) as a hard segment and 1,4-butanodiol (BDO) as a chain extender. FTIR, 1H NMR, 13C NMR and GPC were used to characterize the structure of the fluorinated polyurethane. Thermal stabilities of the fluorinated polyurethane and the corresponding hydrogenated polyurethane were studied by TGA. XPS analysis at two different sampling depths for the fluorinated polyurethane was used to investigate the surface compositions of FPU. The results showed the fluorine enrichment on the surface of FPU.

A UV crosslinkable waterborne siloxane–polyurethane dispersion, PDMS-PEDA-PU, was synthesized by incorporating acrylate groups into the side chain of the polyurethane using pentaerythritol diacrylate (PEDA). Polysiloxane groups were introduced into the soft segment of the polyurethane using polydimethylsiloxane (PDMS). They formed a crosslinking structure after UV radiation. The structure of PDMS-PEDA-PU was confirmed by the use of Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) analysis indicated that the formed PDMS-PEDA-PU was amorphous. The curing rule of PDMS-PEDA-PU was investigated on the basis of the change in C=C conversion during the UV curing process. The influence of the PDMS/PEDA ratio was studied with respect to the water resistance, the thermal property, and the mechanical property of the films.

A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50°C. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.

The chain segment motion, charge trapping and detrapping in γ‐irradiated nylon 1010 films (doses in the range 0–2,000 kGy were used) have been investigated by means of thermally stimulated depolarization current (TSDC). There are three current peaks (named α, ρ1 and ρ2, respectively) in the TSDC spectra, corrected by spontaneous current, above room temperature. By analyzing the characteristic parameters of the three peaks, it is found that the chain segment motion in the amorphous regions becomes more difficult at low irradiation dose (

A new cross‐linkable waterborne siloxane‐polyurethane dispersion (PEDA‐SiPU) was synthesized by incorporating the acrylate groups into the side chain of the polyurethane using the pentaerythritol diacrylate(PEDA) and introducing polysiloxane groups into the soft segment of the polyurethane using dihydroxybutyl‐terminated polydimethylsiloxane (PDMS). They can form the cross‐linking structure by UV radiation in the presence of a photo‐initiator. Fourier transform infrared spectroscopy (FTIR) was used to identify the chain structure of PEDA‐SiPU. The effect of the PDMS content and the PEDA content on the C˭C conversion behaviors under UV irradiation was investigated. Water resistance and the mechanical properties of the UV cured films were also studied. Through the controlling of suitable content of PDMS and PEDA introduced in the chain, the obtained PEDA‐SiPU films were proved to possess both good water resistance and mechanical properties.

Poly(methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (Mη ∼2×105) with different mass percentages of MMA were synthesized by the method of solution polymerization. Thermally stimulated depolarization current (TSDC) technique was used to investigate the effect of copolymerization on pendant group and chain segment motions. Three TSDC peaks were observed over the temperature range from 310 to 400 K. The highest temperature, ρ peak originates from the detrapping of trapped charge carriers. The lower temperature, α peak corresponds to the glass transition. The activation energy of the α relaxation decreases from 1.2 eV for PMMA to 0.98 eV for MMA(75)/BA(25). In the fitting process, another peak, β′, is separated on the low temperature side. The apparent energy barrier of the β′ for PMMA is 0.80 eV. The β′ relaxation is thought to correspond to the motion of pendant groups including intra‐ and inter‐molecular interactions. All three peaks move to lower temperatures with an increase in BA component, a...

A novel core–shell type fluorinated acrylic and siliconated polyurethane (FSiPUA) hybrid emulsion was prepared by seeded emulsion polymerization using siliconated polyurethane (SiPU) as a seed and forming the structure with SiPU as a shell and the copolymer of butyl acrylate (BA) with 2,2,2-trifluoroethylmethacrylate (TFEMA) as a core. SiPU was synthesized using isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), dihydroxybutyl-terminated polydimethylsiloxane (PDMS), dimethylol propionic acid (DMPA), 1,6-hexanediol (HDO) and triethylamine (TEA). The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy (FTIR) was used to identify the chain structure of SiPU and FSiPUA. Investigation of transmission electron microscopy (TEM) confirmed the core–shell structure of FSiPUA emulsion and gave the particle size at about 50 nm. The measurement results of water contact angles and the solvent absorptions in water and n-octane for cured films showed that the water and the oil repellency for FSiPUA had been improved significantly with a suitable content of fluorine and siloxane.

The silylation reaction of polytetramethylene glycol (PTMG) with trimethylchlorosilane (TMS) in DMSO was studied as the first step of the synthesis of new fluorinated polyether glycol. The extent of silylation was measured by 1H‐NMR, and the silylation product was characterized with FTIR, 1H‐NMR. The effects of the experimental conditions, i.e., reaction time and temperature, silylation reagent concentration (TMS/OH molar ratio) were investigated. The increase in reaction temperature and reaction time favored the silylation yields. After grafting reaction and ultimate deprotection of the silylated PTMG, novel fluorinated polyether glycol could be readily recovered.

The acetylation reaction of polytetramethylene glycol (PTMG) with acetic anhydride in pyridine was studied. The extent of acetylation was measured by 1H-NMR, and the acetylation product was characterized with FTIR, 1H-NMR, and 13C-NMR. The effects of the experimental conditions, i.e., reaction time and temperature, acetylation reagent concentration (anhydride and hydroxyl molar ratio), were investigated. The increase in reaction temperature and reaction time favored the acetylation yields. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1138–1142, 2007

Poly (methyl methacrylate/butyl acrylate) [P(MMA/BA)] copolymers (M η∼2×105) with different mass percentages of PMMA (100/0, 90/10, 81/19, and 75/25), were synthesized by the method of solution polymerization. In addition to the normal α and ρ peak, a third τ peak is observed in thermally stimulated depolarization current (TSDC) spectra of the copolymers in the high temperature region. The α peak‐corresponds to the glass transition, the ρ peak originates from the detrapping of trapped carriers in the bulk amorphous structure related with flexible side groups, and the τ peak can be attributed to the charge detrapping related to the liquid–liquid transition of the copolymers. The three peaks all move to lower temperature with an increase of the BA component, indicating that the flexible side groups of butyl acrylate not only have an effect of plasticization on the glass transition and liquid–liquid transition, but also make the trap depth shallower and the detrapping process easier for the ρ and τ peaks. Th...

Maxwell–Wagner–Sillars (MWS) relaxation in nylon 1010, arising from charge carriers accumulated at the interphase between amorphous and crystalline regions, has been investigated by means of dielectric relaxation spectra. In the frequency spectra of nylon 1010, dielectric permittivity showed high values at low frequencies originating from charge carrier movement. For the MWS relaxation, the dielectric strength was independent of temperature. The results revealed that there is a transition temperature, located between 110 and 120°C, resulting in the separation of two different charge carrier movement mechanisms. Below and above this transition temperature, the temperature dependence of the MWS relaxation time follows the Vogel–Tammann–Fulcher type, showing that the charge carrier transport is governed by the motion of the polymer chains. The change of charge carrier movement mechanisms is due to the onset of polymer chain motion in the interphase.

Electrode polarization arising from charge carriers accumulating at the interface between an electrode and nylon 1010 was investigated with dielectric relaxation spectroscopy. In the frequency spectra of nylon 1010, the dielectric permittivity showed high values in the region of low frequencies and high temperatures. With the Havriliak–Negami function used to fit the experimental spectra, the result revealed that the high values originated from electrode polarization and direct-current conductivity. For electrode polarization, the dielectric strength, independent of the temperature, was about 1150, and the temperature dependence of the relaxation time followed the Vogel–Tammann–Fulcher equation. Fitting with the Vogel–Tammann–Fulcher equation, the parameters τ0 = 1.33 × 10−10 s and T0 = 303.2 K were proposed (where τ0 is the relaxation time at a very high temperature and T0 is the temperature at which the relaxation time becomes extremely large), and they suggested that the motion of the polymeric chains was one of the factors leading to charge-carrier transport at temperatures higher than the glass-transition temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3590–3596, 2006

Amine-terminated hyperbranched polymer (HBP-NH2), as an inhibitor in water-based drilling fluid, is prepared by the polycondensation of diamine AB2 monomers. The primary amine and secondary amide structures are confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Through time of flight mass spectrometry, the molecular weight of HBP-NH2 is mainly distributed in the range of 200–1400. Also, the quasi-spherical shape and the high temperature resistance (200 °C) performance of HBP-NH2 are, respectively, certified through the environmental scanning electron microscope and the thermogravimetric analysis. In the inhibition performance test, the linear expansion rate of sodium bentonite in 3 wt % HBP-NH2 aqueous solution is only 11.42%, which is lower than other inhibitors (KCl, FA-367, and HPAM). Zeta potential analysis shows that HBP-NH2 has a strong ability to inhibit the hydration and dispersion of sodium bentonite by protonated primary amine groups. Compared with the base slurry, the absolute value of zeta potential is reduced by 25.5 mV in the slurry containing 3 wt % HBP-NH2 at 180 rpm. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45466.

The microstructure and mechanical properties of aged Mg-10Y-2.5Sm alloy were investigated. The results showed that the microstructure of the alloy consisted of α-Mg matrix and Mg 24 Y 5 phase, and fine Mg 24 Y 5 particles distributed in a-Mg matrix uniformly and dispersedly. Sm enhanced α-Mg matrix and Mg 24 Y 5 phase by solid solution effect. At 200-300 °C, the ultimate tensile strengths were more than 200 MPa and the elongations were about 3%. Compared with those at room temperature, the mechanical properties had no obvious changes.