Search

A series of sulfonated hydroxypropyl guar gum (SHG) samples with different degrees of substitution (DSs) were prepared, and the SHG solution and SHG fracturing fluid were prepared and analyzed. The SHG aqueous solutions with different DSs all exhibit shear thinning behavior, which is well correlated with the Ostwald-deWaele model. Owing to the electrostatic repulsion of SHG molecular chains, SHG solutions with a higher DS will exhibit weaker thixotropic performance and strong anti-salinity ability. In addition, the SHG fracturing fluids, which were formed by interactions between SHG and organic zirconium, exhibit good temperature- and shear-resistant properties, proppant suspension properties, and salt tolerance. Furthermore, SHG gel-breaking fluids show low interfacial and surface tensions, with low residue content and small core permeability damage. These results provide useful indicators for the applications of SHG in the oil field industry. [ABSTRACT FROM AUTHOR]

The rheology of carboxymethyl fenugreek gum (CFG) is characterized and applied it as a binder for the silicon anode of lithium-ion batteries (LIBs). First, a series of carboxymethyl fenugreek gum (namely CFG-1, CFG-2 and CFG-3) was prepared and characterized by Fourier transform infrared spectrophotometer and hydrogen nuclear magnetic resonance spectrometry studies. In rheological measurements, the CFG solutions show higher flowability, weaker viscoelastic behavior and better thixotropy than that of fenugreek gum (FG) solution. Furthermore, the higher degrees of substitution (DS) of CFG solutions lead to lower apparent viscosity and higher flow index, weaker elastic effect and smaller relaxation time, and higher viscosity recoverability than those obtained for lower DS of CFG solutions. In electrochemical measurements, the polar hydroxyl and carboxyl groups in the CFG skeleton chain provide bonding points between the CFG binders and the silicon electrode to produce binder-silicon bonds, which cause strong hydrogen bonding, and resulted in excellent electrochemical stability and specific capacity. The electrochemical performances were measured via the silicon electrodes with FG and CFG at 5 wt% content. As the DS is increased, the initial Coulombic efficiency can increase from 88.74% to 91.3%. When the electrode undergoes a volume change, the CFG binder with silicon electrodes can hold high capacity of above 1500 mAh/g after 200 charge-discharge cycles. Therefore, the carboxymethyl fenugreek gum as a binder may also be a novel extended binder-design, with applications for silicon anodes of LIBs. [ABSTRACT FROM AUTHOR]

To better understand the guar gum (GG) working process, we divided it into three steps: dissolution, gelation, and gel breaking. Freeze-drying and scanning electron microscopy were used to examine the microstructures of GG in different states. The dissolution step could be divided into two processes: swelling and dissolving. The microstructures during these two processes were lined structures and random ribbon-like structures, respectively. Further, during the gelation step, the random ribbon-like structures transformed to crosslinked ordered structures. Finally, the ribbon-like structures were broken in the gel breaking step, but the orderliness was not broken. These findings are beneficial to the potential modification or design of GG and the improvement of its hydrogel performance. [ABSTRACT FROM AUTHOR]

To explore the application of pH-responsive surfactant, a pH-responsive N , N -dimethyl-erucamide-propylamine (DEAPA) self-assembly system was prepared and characterized. The rheological property and structural transformation of DEAPA molecular aggregations were comprehensively discussed with decreasing pH or increasing of Cl − concentration using rheology, dynamic light scattering (DLS), ultraviolet-visible (UV) spectrophotometry, and cryo-transmission electron microscopy (cryo-TEM). The properties of the DEAPA-KCl viscoelastic fluid used as the fracturing fluid were discussed in terms of the viscoelasticity, temperature-tolerance, and shear-tolerance, proppant suspension, and core permeability damage at pH 1.5. Results revealed that the microstructure of the DEAPA micelle first transformed from vesicles to spherical micelles, and finally changed to worm-like micelles when HCl solution was added. In addition, on increasing the KCl concentration, the system transforms from spherical micelles to worm-like micelles. When the Cl − concentration was increased to 0.50 mol/L (pH = 1.5), the storage modulus ( G ′) of the DEAPA-KCl fluid became over 15 Pa and loss modulus ( G ″) was over 5 Pa, which suggests that elasticity is the predominant property of these worm-like micelles. Also, the viscosity of the DEAPA-KCl fracturing fluid was constant at about 110 mPa s at 80 °C and shear rate of 170 s −1 . The settling velocity of the DEAPA-KCl fluid was lower than 0.004 mm/s at 60 °C, and the core permeability damage was 6.75%. Therefore, the DEAPA-KCl system is suitable for use as an acidic viscoelastic fracturing fluid. [ABSTRACT FROM AUTHOR]

An ultralow interfacial tension (IFT) oil displacement agent, which was a surfactant combinational system (HCS) with good salt and heat resistance, was synthesized using amphoteric betaine (AMS)/anionic sulfonate (AKS)/nonionic alkyl amide (NIS). The interface tensiometer was used to test the IFT. The results showed that the oil–water IFT could be as low as 10−4mN/m when the salinity is 10,000∼50,000 mg/L, the concentration is 1∼5 g/L, and the temperature is 40∼80°C. The surfactant system has good emulsification stability. The displacement simulation experiments demonstrated that the increment of the recovery ratio can be up to 14.1%. The surfactant system could meet the demands of site operation. [ABSTRACT FROM PUBLISHER]

A new guar gum derivative was synthesized though the nucleophilic substitution of sodium hydroxide-activated guar gum with n -butyl glycidyl (BGE) ether. The physicochemical properties of 2-alkenyl-3-butoxypropyl guar gum (ABPG) were characterized by attenuated total reflection Fourier transform infrared spectrometry (ATR-FTIR), X-ray diffraction (XRD) and thermal gravimetric analyses (TGA). The results showed that sodium hydroxide can be effectively substituted with BGE to form the ABPG. The steady and dynamic rheological properties of the aqueous solution and ABPG gel were determined using an RS6000 rheometer. Compared with the guar gum, ABPG enhanced the thickening property and improved the solution stability. The ABPG gel exhibited good temperature resistance and shear stability properties. [ABSTRACT FROM AUTHOR]

Novel eco-friendly sulfonated polyurethane/polyacrylate (SPUA) emulsions were synthesized by surfactant-free emulsion polymerization method using PU as seeds. The sodium sulfonate modified polyester polyol (SDNP) was used as internal emulsifier to make the PU emulsion disperse in deionized water. Effects of the SDNP content on the properties of the emulsions and membranes were studied. Dynamic light scattering (DLS) result showed that the average particle sizes of SPUA emulsions decreased first from 124.1 nm to 102 nm when the SDNP content was lower than 40 wt% and then increased to 138 nm. Transmission electron microscopy (TEM) morphology showed that the particle sizes were all spherical and an apparent core-shell structure was observed. Fourier transform infrared spectroscopy (FT-IR) result ascertains that SPUA was successfully prepared. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the carbon, oxygen, nitrogen, sulfur, and sodium peaks were all revealed and the polyurethane component was rich in the upper surface. Thermo gravimetric analysis (TGA) of the membranes showed that the thermal stability of the SPUA membranes was enhanced by increasing the SDNP content. Scanning electron micrograph (SEM) results demonstrates that the coexistence of a dual phase. The SPUA could be used as adhesives in footwear industry, and the T-peel strength of the SPUA membranes increased from 5.98 N/mm to 12.06 N/mm when the SDNP content was up to 40 wt%. The wettability of SPUA emulsions on the rubber surface results showed that the emulsions could wet the rubber surface well. [ABSTRACT FROM AUTHOR]

Titanium (Ti) oral implants, as foreign bodies, can easily trigger an inflammatory response, and the metal ions/nanoparticles released by friction/corrosion in the body can also damage soft and hard tissues, leading to implant failure. To make up for deficiencies, a multifunctional composite coating composed of silica (SiO 2) particles and zirconium hydrogen phosphate (ZrP) on the surface of Ti was prepared by combining micro-arc oxidation (MAO) and sol-gel technology. The characterization results of the surface physicochemical properties confirmed that a series of SiO 2 /ZrP-modified MAO coatings were successfully constructed. Compared with the control group, the doping of SiO 2 particles effectively improved the friction resistance of the surface MAO coating, but worsened its corrosion resistance. After the surface was further covered with ZrP coating, the corrosion resistance defect caused by SiO 2 particles was eliminated. With the increase of the ZrP thickness, the friction resistance of the target sample increased gradually. In addition, the specimens coated by ZrP coatings also presented better anti-inflammatory and osteogenic capabilities than the samples subjected to pure/SiO 2 -doped MAO treatment. Based on these advantageous properties, this novel composite coating may project good application prospects in promoting early osseointegration. • Combined application of SiO 2 particle and ZrP coating to modify Ti for the first time. • ZrP coating further enhanced the friction resistance of the SiO 2 -doped MAO coating. • The corrosion defect caused by SiO 2 particles can be eliminate by ZrP coating. • SiO 2 and ZrP synergistically improve the osteoinductive ability of MAO coating. • ZrP coatings significantly reduce the early immune rejection of MAO-treated titanium. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel multiple cross-linked PVA nanocomposite (MPAU) was constructed. • Incorporation of SiO 2 provides physical cross-linking domains. • PVA, TBPU and BGT generate chemical-coordination domains. • MPAU show excellent mechanical strength (58.9 MPa) and toughness (79.5 MJ/m3). Materials based on fiber-reinforced coating have gained increasing attention due to their environmental and industrial application tracks. Polyvinyl alcohol (PVA) composites with interpenetrating cross-linked structures and abundant functional groups exhibit obvious advantages for high-performance coating. In this work, PVA multiple cross-linked network nanocomposites (MPAUs) were established using silica nanoparticles as reinforcing fillers, ingeniously synthesized boronic esters (BGTs) and blocked-diisocyanate polyurethanes (TBPUs) as cross-linkers. Briefly, SiO 2 nanoparticles were evenly dispersed into PVA matrix to fabricate primary physical cross-linked network, which could promote subsequent cross-linking and esterification effects. After deblocking, TBPU molecules were grafted onto PVA chains via radical polymerization. Meanwhile, the borate ions B(OH) 4 − generated by the multi-stage ionization of BGT were re-coordinated with the hydroxyl groups of PVA matrix. These two effects further afforded secondary chemical cross-linking networks and coordination cross-linked domains. The mechanical and microstructural properties of MPAUs were assessed with respect to their cross-link density and multiple cross-linked network structure. Of note, the formation of multiple-cross-linking network enabled MPAU films with substantial enhancements in mechanical strength and toughness, reaching to 58.9 MPa and 79.5 MJ/m3, respectively. The results of application studies indicated that the obtained MPAUs could integrate with cellulose paper to accomplish excellent physical strength and surface properties. In conclusion, this work paves the way to fabricate multifunctional nanocomposites, which enriches the commercial value of versatile paper-based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel multiple cross-linked PVA nanocomposite (MPAU) was constructed. • Incorporation of SiO 2 provides physical cross-linking domains. • PVA, TBPU and BGT generate chemical-coordination domains. • MPAU show excellent mechanical strength (58.9 MPa) and toughness (79.5 MJ/m3). Materials based on fiber-reinforced coating have gained increasing attention due to their environmental and industrial application tracks. Polyvinyl alcohol (PVA) composites with interpenetrating cross-linked structures and abundant functional groups exhibit obvious advantages for high-performance coating. In this work, PVA multiple cross-linked network nanocomposites (MPAUs) were established using silica nanoparticles as reinforcing fillers, ingeniously synthesized boronic esters (BGTs) and blocked-diisocyanate polyurethanes (TBPUs) as cross-linkers. Briefly, SiO 2 nanoparticles were evenly dispersed into PVA matrix to fabricate primary physical cross-linked network, which could promote subsequent cross-linking and esterification effects. After deblocking, TBPU molecules were grafted onto PVA chains via radical polymerization. Meanwhile, the borate ions B(OH) 4 − generated by the multi-stage ionization of BGT were re-coordinated with the hydroxyl groups of PVA matrix. These two effects further afforded secondary chemical cross-linking networks and coordination cross-linked domains. The mechanical and microstructural properties of MPAUs were assessed with respect to their cross-link density and multiple cross-linked network structure. Of note, the formation of multiple-cross-linking network enabled MPAU films with substantial enhancements in mechanical strength and toughness, reaching to 58.9 MPa and 79.5 MJ/m3, respectively. The results of application studies indicated that the obtained MPAUs could integrate with cellulose paper to accomplish excellent physical strength and surface properties. In conclusion, this work paves the way to fabricate multifunctional nanocomposites, which enriches the commercial value of versatile paper-based materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple process was employed for synthesizing stable lipid-polymer hybrid nanoparticles. • Bone-targeting oligopeptides modified nanoparticles showed bone affinity in vitro and in vivo. • The nanoparticles show a potential in the treatment of osteoporosis. The lack of safety, efficacy, and specificity has made the delivery of anti-osteoporotic drugs at a proper dose a challenge. In our study, cathepsin K inhibitor loaded poly (D, L-lactide-co-glycolide) derived lipid hybrid nanoparticles (DNPs) were modified with bone-specific polyaspartic acid [(Asp) 8 -DNPs] to treat osteoporosis. (Asp) 8 -DNPs showed its hydroxyapatite binding affinity and achieved a sustained release of cathepsin K inhibitor for up to 5 days. Cathepsin K inhibitor loaded (Asp) 8 -DNPs significantly decreased the tartrate-resistant acid phosphatase (TRAP) activity and resorption-related genes in osteoclasts. Animal studies also exhibited high accumulation of (Asp) 8 -DNPs in the tibia and femur and a greater bone mass in trabecular bone and better organized three-dimensional architecture in osteoporotic rat models. Herein, the bone targeting drug delivery system show its potential in treatment of osteoporosis. [ABSTRACT FROM AUTHOR]

Novel polyurethane/polyacrylate (PUA) composite emulsions were synthesized by soap-free emulsion polymerization method from methyl methacrylate (MMA), butyl acrylate (BA), and 2-Hydroxyethyl acrylate (HEA) in the presence of PU as seeds and a polymerizable emulsifier-Allyloxy hvdroxyl propanesulfonic salt (AHPS). Effects of the AHPS content on the properties of the emulsions and films were studied. Dynamic light scattering (DLS) result showed that the average diameters and polydispersity were decreased with the increment of AHPS content. Fourier transform infrared spectroscopy (FT-IR) result shows that AHPS was introduced into the PUAS chains. Their thermal stability and Tg of the films increased gradually with augment of AHPS amount in polymer. X-ray photoelectron spectroscopy (XPS) analysis showed that sodium was preferably enriched on the surface of latex particles. Atomic force microscopy (AFM) observation performed the extremely flat membrane. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new epoxide modified polyurethane/polyacrylate emulsion was synthesized. [•] Surface tension analysis assured the surface activity of the polyurethane emulsion. [•] The ring-opening mechanism between epoxide and carboxylic acid groups was discussed. [•] The fitting peak results confirm the formation of polyurethane/polyacrylate. [Copyright &y& Elsevier]

The rheological behaviour of solutions of dimethylene-1,2-bis (tetradecyl ammonium bromide) (GS14-2-14), dimethylene-1,2-bis (hexadecyl ammonium bromide) (GS16-2-16) and dimethylene-1,2-bis (octadecyl ammonium bromide) (GS18-2-18) at a surfactant mass concentration of 20 g L−1, is investigated, respectively, as a function of temperature and shear rate by dynamic-state rheological measurements. It is confirmed that the elastic or storage modulus (G′) and the viscous or loss modulus (G′′) are reduced first and then be equal under the increase of temperature. When the angular frequency is improved, G′ and G′′ appear to be increased first and then become straight. These results are in agreement with the prediction of linear viscoelasticity theory of pseudoplastic fluid. However, the quantitative analysis of the results (Cole–Cole plots, loss factor tgδ and dynamic viscosity η′(ω)) on the basis of the theory reveals some inconsistencies. Those results can be analysed by shear-thinning effect and shear-induced effect separately. [ABSTRACT FROM PUBLISHER]

[Display omitted] • Introduce the end-blocked structure into the water-based functional polyurethane segments applied as a "latent cross-linker" for surface sizing, • A novel compound sizing system containing water-based blocked polyurethane and polyvinyl alcohol, • Chemical bonding and hydrogen bonding between highly active isocyanate groups and paper fiber after unblocking, • Application of water-based blocked polyurethane in surface sizing of special paper. Efficient improvement of paper strength while optimized sizing technique remains challenging and fascinating since specialty paper are required to low-cost, high printing quality and environmental sustainability. Herein, a novel controlled reactivity polyester glycol-based cross-linker (TBPU) applied in paper surface sizing was exploited by simple two-steps polymerization and blending process. An end-blocked structure design strategy of containing densely distributed multiple soft segments and active hydrogen nucleophilic segments (Butanone oxime, MEKO as end closure units) in isocyanate dispersion was achieved to address the scarcity of mechanical properties and the inconvenient in surface-sizing progress. TBPU can block the NCO groups in IPDI segments at 60 °C, and NCO groups can be deblocked at the temperature higher than 110 °C, which endow TBPU with latent cross-linking property. Afterward, we took advantage of the structural feature of polyhydroxy compounds and the adhesion to cellulose via using polyvinyl alcohol (PVA) as a blending component to form TBPU/PVA emulsion. The organization of NCO groups react with hydroxyl groups, carbamate groups cross-linked with hydrogen bonds, and crystallized PCL segments generates phase-separated hierarchical domains. Serving as high-reactivity paper-sizing fillers capable of cross-linking and disintegration under an external change of temperature, the hierarchical domains can strengthen the specialty papers and enhance their water resistance and ink adhesion. The influences of TBPU content, PVA content and NCO/ OH molar ratio on the physicochemical properties of the resultant emulsions and sized paper have been investigated. As a result, the paper sized with TBPU-1.6/PVA emulsion exhibit a tensile index of ≈107.19 Nm/g, a tearing index of ≈11.79 m N • m2/g, a folding resistance of ≈4511 s, an optimum blending temperature of 70 °C and exceptional cooperation ratio with PVA and TBPU (4.0 wt%, 3.0 wt%), which are 1.649 times, 1.966 times, and 2.652 times than those of untreated papers (65 Nm/g, 6 m N • m2/g, 1701 s). Furthermore, sizing liquid can be conveniently applied and recycled due to their excellent environmental friendliness and Biodegradability, this work provides a promising solution for optimizing surface sizing technology. [ABSTRACT FROM AUTHOR]

Hydroxyl-terminated polyurethane (EPPU) modified by epoxy resin was synthesized. The structure of polyurethane (PU) was characterized by Attenuated total reflection Fourier transform infrared spectrometer (ATR-FTIR) and transmission electron microscope (TEM). The effect of w(E-44) on thermal stability and mechanical properties of the membranes were also measured. ATR-FTIR and TEM indicates that epoxy resin has been successfully incorporated into the copolymer's main chain, and the thermal stability has improved. It was found that greater mechanical properties of PU were obtained when chemical networks were formed between PU and epoxy resin. The maximum tensile strength is up to 6.99 MPa. [ABSTRACT FROM AUTHOR]

Waterborne cationic fluorinated polyurethane (WCFPU) micro-emulsion was prepared by the reaction of isophorone diisocyanate (IPDI), polytetramethyleneether glycol (PTMG1000), 1,4-butanediol (BDO), N-methyldiethanolamine (MDEA), trimethylolpropane (TMP) and perfluoroalkylethyl octanol (FEOH), and then the films of the WCFPU were prepared. The influence on the mechanical properties and water absorption of the films, such as the molar ratio of NCO to OH, the dosage of MDEA, TMP and FEOH, was investigated. Their structure, morphology and heat performance were characterized by fourier transform infared spectrometer (FT-IR), dynamic light scattering (DLS), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and thermogravimetry (TG). The results revealed that the best mechanical properties and water resistance could be obtained under the condition that NCO/OH molar ratio was 1.25, w(TMP) was 1.1%, w(MDEA) was 7.29% and w(FEOH) was 22.3%. In addition, WCFPU was endowed with low surface energy of its film and the membrane surfaces had excellent water and oil repellency. Furthermore, the thermal stability of the waterborne cationic fluorinated polyurethane increased with the incorporation of perfluoroalkyl chain. And XRD, DSC and TG showed that micro-crystallinity of polyurethane increased with the increase of FEOH, which was benefit to the micro-phase seperation. [ABSTRACT FROM AUTHOR]

Self-crosslinkable polyurethane emulsion containing active carbonyl group was obtained using dihydroxyketon N-[(1,1-dimethyl-2-acetyl)ethyl]-β-dihydroxyethylamino propanamide(DDP) and 1,4-butanediol as chain extenders, isophorone diisocyanate (IPDI), polyether polyol (PTMG1000), dimethylol propionic acid (DMPA) and trimethylol propane (TMP) as main materials, γ-aminopropyltriethoxysilane (APTES) as end capping agent. Then adipic dihydrazide was added into the emulsion. The structure and composition of DDP and the films were confirmed by means of FTIR and H nuclear magnetic resonance (H-NMR) spectrometer, the test results indicated that the reaction between ketone carbonyl and hydrazine has happened during the film curing. The effects of n(NHNH-)/ n(C=O) and DDP content on the properties of the films were studied. The results show that water absorption of the films decreases from 39.3% to 18.9%, crosslinking degree increases from 51.5% to 90.2%, tensile strength increases from 20.1 MPa to 28.3 MPa and pencil hardness is 2H when the DDP content increases from 0% to 6.13%. TGA analysis indicates that the Ketone-Hydrazide crosslinking structure can improve thermal stability of the films. [ABSTRACT FROM AUTHOR]

Abstract: The cationic polyurethane-fluorinated acrylic (PUFA) hybrid latexes were obtained from double bond-end capped polyurethane macromonomer having quaternary ammonium groups with perfluoroalkyl acrylate (FA) by radical copolymerization. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) confirmed that the FA monomer had been introduced into the chain of the PUFA hybrid polymer. Particle size distribution (PSD) analysis showed that the particle size of PUFA increased with the increase of the FA content. TEM indicated that the PUFA hybrid possessed core–shell structure. The analysis of the contact angles (CAs), XPS and atomic force microscopy (AFM) had shown that there was a remarkable enrichment of fluorine on the film–air interface, which was more evident when the PUFA hybrid film annealed at higher temperature. At the same time, the influences of the soft segment molecular weight, the N-methyldiethanolamine (MDEA) content and the FA content on other properties such as the surface tension of the PUFA latexes, the surface free energy of the PUFA films and the thermal properties were studied. The results showed that the MDEA content had contrary influence on latex''s and film''s surface properties. Thermal stabilization usually brought by fluorine was not observed in our investigated systems. [Copyright &y& Elsevier]

The polyurethane prepolymer was synthesized, and hydrophilic nano-sized silica (A200) was added to the prepolymer with KH550 as a coupling agent, then a waterborne polyurethane/nanosilica hybrid material (WPUNS) was obtained by a sol-gel process. The structure and performance of the WPUNS films were studied by FTIR, TG, DSC and physical mechanical testing. The particle size and distribution of WPUNS hybrid emulsion was analyzed by a dynamic light scatter (DLS). The morphology of emulsion and films were observed by Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM), respectively. FTIR analysis indicates the formation of chemical bond between WPU and A200. TEM images display that A200 particles were encapsulated by PU macromolecules and formed a composite particles structure. As the mass fraction of A200 increased from 0 to 2%, the particle size increased from 79.9 nm to 139.9 nm, the tensile strength of the films increased from 6.32 MPa to 20.46 MPa, water absorption decreased from 28.3% to 6.3%, and the hardness was also improved. The TG result indicates that A200 can improve thermal stability of WPUNS. DSC shows that there is no clear effect of nanosilica on the glass transition of soft segments. AFM displays that the smoothness of the films increases with A200 addition. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane prepolymer was prepared by the reaction of isophorone isocyanate(IPDI), polyether polyol(PTMG), dimethylol propionic acid(DMPA) and trimethylol propane(TMP), which was modified by silicane coupling agent(APTES) to form highly crosslinked polyurethane emulsion. The films of the waterborne polyurethane were prepared. The structure of the polyurethane was characterized by Fourier transform infared spectrometer (FTIR), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The mechanical properties and water absorption of the films were measured. FT-IR indicates that APTES reacted with -NCO of polyurethane. XRD and DSC shows that crystallinity of polyurethane decreased with the increase of w(APTES). Tensile strength increases as the NCO/OH ratio increases. Tensile strength of films increases with increase of w(DMPA) and elongation at break decreases. The water absorption decreases with the increase of w(TMP) when w(TMP) is lower than 1.8%. As the mass fraction of APTES increases from 0% to 10%, the tensile strength of PU films increased from 18 MPa to 28 MPa, water absorption and ethanol absorption decreased. [ABSTRACT FROM AUTHOR]

Amphoteric polyacrylate containing long hydrophobic aliphatic chain in the presence of poly(vinyl alcohol) (PVA) was synthesized. The influences of PVA on the properties of the emulsion and its film were investigated in details. In addition, the emulsion and the film were characterized by various examining methods. Furthermore, the applied properties of paper sized by amphoteric polyacrylate in the presence of poly (vinyl alcohol) were measured, in contrast to acrylic polymer prepared with the conventional low molecular weight emulsifier, the physical indexes were all improved. [ABSTRACT FROM AUTHOR]

A novel cationic polyacrylamide modified with fluorinated acrylate had been synthesized of acrylamide (AM), methacryloxyethyl trimethylammonium chloride (DMC), and 2-(perfluorooctyl)ethyl acrylate (FEA) by free radical micellar copolymerization in aqueous solution utilizing cetyl trimethylammonium bromide (CTAB) as the surfactant and potassium persulfate (KPS)/sodium bisulfite (SBS) as the redox initiator. Some factors affecting synthesis, such as the amount of FEA, CTAB, and KPS, were described. Surface activity and flocculation of the polymer were studied. The results showed that with the incorporation of FEA, the intrinsic viscosity decreased until the modified polymer was not able to dissolve in water; and with the increase of CTAB and KPS, the intrinsic viscosity decreased firstly then increased slowly. The polymer exhibited good surface activity in both water and salt solution. Its flocculation properties were evaluated with kaolin suspensions using a standard jar test. The results demonstrated the superiority of the copolymer over the no-modified cationic polyacrylamide as a flocculant. [ABSTRACT FROM AUTHOR]

The anionic hydrophobic association polyacrylamide (AFPAM) modified with fluorinated acrylate have been synthesized of acrylamide (AM), 2-acrylamide-2-methyl propanesulfonic acid (AMPS) and 2-(perfluorooctyl)ethyl acrylate (FEA) by free radical micellar copolymerization in aqueous solution utilizing sodium dodecyl sulfate(SDS) as the surfactant and potassium persulfate(KPS)/sodium bisulfite(SBS) as the redox initiator. The solution properties of these polymers were investigated. The results show that there are strong hydrophobic associations in the AFPAM aqueous solution. The intrinsic viscosity decreases and Huggins constant increases with the increase of hydrophobic FEA content. The addition of NaCl and CaCl2 results in an increase of solution viscosity which indicate the good salt-resistant performance. The polymers exhibit good temperature tolerance property, shear-thickening and thixotropy behavior. Additionally, the AFPAM has higher surface activity in salt solution than in water. [ABSTRACT FROM AUTHOR]

Abstract: A series of cationic waterborne polyurethane dispersions (SiPU) modified with hydroxysilane (HPMS) were successfully synthesized based on poly(oxytetramethylene) glycols (PTMG) and isophorone isocyanate (IPDI), and the films were obtained by casting the dispersions on tetrafluoroethylene (TFE) plates. Effects of HPMS content on micromorphology, particle size of the dispersions were studied, as well as thermal properties, phase behavior and surface structure of the films. The particles had the morphology of a solid sphere, with particle size varying from 17.1 nm to 114.4 nm corresponding to the increase of HPMS concentration, which can be attributed to the increase of interfacial tension. XPS spectra indicated the surface migration of Si element in the process of film forming, and the SiPU surface was mainly composed of soft segments. DSC analysis, together with TG-DTG-DTA results demonstrated the HPMS soft segment merged with the transition region of PU matrix, forming part of polyurethane backbone, but an improved microphase separation was observed when HPMS concentration greater than 15%. It was also found that incorporation of flexible HPMS prevented the degradation of polyurethane backbone, resulting in the increase of thermal stability in ultimate copolymer. [Copyright &y& Elsevier]

Waterborne fluorinated polyurethane–acrylate hybrid emulsion modified by long aliphatic chains (WFPUA) is prepared by two steps, which include that the stearyl alcohol (SA)-blocked (end-capped) polyurethanes (SPU) are carried out in the mixtures of vinyl monomers, and then, the WFPUA is prepared via the free radical polymerization after the pre-emulsification of the said system. The characteristic of the reaction is the phase-inversion polymerization. The results show that the emulsifiability of SPU is firstly improved then decreased with the continuous increase in SA content. When the molar ratio of SA to 2-hydroxyethyl methacrylate (HEA) in the SPU is 1:1, the stability, zeta potential, viscosity and particle sizes of the WFPUA emulsion have the best results. The mechanical properties of WFPUA hybrid films deteriorate with the increase in SA content at 20 °C, but the mechanical properties of WFPUA films with more SA content achieve better results at 80 °C. The fluorinated groups migrated to the surfaces more easily with more SA content. In order to form the liquid crystalline-like structure on the WFPUA's surface, the gradient heating treatment to an elevated temperature (i.e., 120 °C) to properly orient the fluorinated chains is necessary. [ABSTRACT FROM AUTHOR]

• β-estradiol (E2) condensed with Ca2+ precursors to form bioresponsive nanocores. • MC3T3-E1 cell membranes expressing azide groups are used for nanocore coating. • The cell membrane coating is functionalized by alendronate for bone targeting. • The nanoparticles restore bone homeostasis for osteoporosis treatment. Osteoporosis is a common bone disease characterized by the systemic disruption of hone homeostasis, where the imbalance between bone resorption and formation causes deterioration of bone structure and bone mass loss. Targeted restoration of bone hemostasis has thus become a promising strategy for osteoporosis treatment. For this purpose, we report a bone-targeted nanoformulation based on CaCO 3 nanomaterials, which could be activated in the acidic osteoporotic microenvironment and cooperatively regulate the activity of osteoclasts and osteoblasts to reverse bone deterioration. Herein, a clinical antiosteoporosis drug β-estradiol (E2) is first biomineralized using CaCO 3 to form physiologically stable nanocores. Meanwhile, azido groups are introduced onto MC3T3-E1 cells through incubation with AC 4 ManNAz. The azido-tagged MC3T3-E1 cell membranes are extracted for the camouflaging of the CaCO 3 @E2 nanocores to enhance their in vivo stability and availability, while also enabling the surface modification of bone-targeting dibenzocyclooctyne-tagged alendronate moieties via copper-free click reaction. After the selective deposition into acidic osteoporotic bone tissues, the CaCO 3 @E2 cores would be spontaneously degraded to release E2 and Ca2+ ions, which would systematically inhibit the activity of osteoclasts while promoting osteoblast-mediated new bone formation, eventually ameliorating the osteoporosis symptoms. This study offers an effective approach for osteoporosis treatment in the clinics. [ABSTRACT FROM AUTHOR]

Graphical abstract The WAR-PANI was synthesized by graft PANI onto alkyd resin and its anti-corrosion properties were studied. The results demonstrated that PANI was successfully grafted onto the alkyd resin and WAR-PANI can offer higher corrosion protection than the WAR and WAR/PANI. Highlights • Anti-corrosion coating WAR-PANI was developed by graft PANI onto alkyd resin. • Comparison study was made between WAR-PANI and physical blend. • WAR-PANI displayed higher corrosion resistance than WAR and WAR/PANI. • WAR-PANI coating also presented long-term anti-corrosion properties. Abstract Waterborne polyaniline grafted alkyd resin (WAR-PANI) anti-corrosion coatings were prepared via the chemical reaction between glycidyl methacrylate (GMA) modified WAR and polyaniline (PANI). The physical blend of PANI and WAR (WAR/PANI) were also prepared for comparison. The obtained WAR-PANI was characterized by fourier transform infrared spectroscopy and transmission electron microscopy. The results show that PANI was successfully grafted onto the chain of WAR. Polarization tests displayed that the corrosion potential of PANI grafted WAR coating became more positive compared with WAR/PANI physical blend, and the cathodic corrosion was effectively inhibited. When the dosage of GMA was 2.67%, the anticorrosion performance of WAR-PANI composite reached the optimum, the corrosion potential shifted from −690 mV to −530 mV, and the corrosion current density decreased from 6.92 × 10−5 to 9.66 × 10−11 A cm2. Electrochemical tests further proved that the impedance modulus and coating resistance of WAR-PANI increased by four orders in comparison with WAR, which were also three orders of magnitude higher than that of WAR/PANI. The surface morphology of the coatings after immersion in 3.5% NaCl solution also demonstrated that the WAR-PANI had good corrosion resistance performance, which displayed much more promising anticorrosion performance for steel substrate than WAR/PANI physical blend. [ABSTRACT FROM AUTHOR]

Foamability, liquid holdup, and foam appearance are key factors that determine dust control efficiencies. As the foam production method of the FoamScan instrument is similar to foaming device used for dust control, and its measurement means can satisfy the requirements of precise measuring, the FoamScan technology is adopted to explore the influence of xanthan gum (XG) and partial hydrolytic polyacrylamide (HPAM) on dust-related foam properties of sodium dodecyl benzene sulfonate (SDBS). It was found that with the increase of the polymer mass fraction, the liquid volume in the foam gradually increased. Additionally, the foaming timet200of the foaming agent decreased at first, then remained almost constant for both polymers, which indicated that the foamability and liquid holdup were enhanced by the addition of polymers into SDBS. In addition, the efficiencies of XG are higher than that of HPAM. The image analysis using the CSA software revealed that the mean radius formed by XG was smaller than that by HPAM and the number of bubbles was larger with XG than with HPAM. Thus, the XG foam has more area to contact with dust and could control dust better. The highly branched molecular structure and hydrogen bonds formed by XG played important roles in dust-related foam properties. [ABSTRACT FROM PUBLISHER]

Self-crosslinkable aqueous polyurethane (PU)/polyacrylate (PA) composite emulsion was obtained by radical copolymerization. Fourier transform infrared spectroscopy (FT-IR) result shows that the cross-linking reaction between the carbonyl group and the hydrazine group has happened. The influence of the hydrazide-carbonyl molar ratio and the PA content on the properties of the composite emulsions and their films were investigated. The results show that, under the optimal hydrazide-carbonyl molar ratio ( n (hydrazine group)/ n (carbonyl group) =1:1), the water absorption is 10.56 %, and the mechanical properties and thermal stabilities are both improved. As the PA content increases from 0 wt% to 15 wt%, the tensile strength increases from 5.7 MPa to 7.3 MPa and the gel content increases from 70.3 % to 87 %. [ABSTRACT FROM AUTHOR]

Through ultrasonic assisted radical polymerization, hydrophobically associating polyacrylamide (U-HAPAM) was prepared by acrylamide (AM), 2-acrylamido −2- methyl propane sulfonic acid (AMPS), and hydrophobic monomer octadecyl acrylate (ODA). The effects of concentration of initiator, ultrasonic frequency power and concentration of total monomers, had great influences on total monomer conversion, relative molecular mass and the viscosity of its aqueous solution. The macroscopic and microscopic self-assembly behaviors of the product was studied through apparent viscometry, fluorescence spectroscopy(FS) and atomic force microscope(AFM) respectively. The results showed that, the ultrasound possessed the certain ability of initiating and 0.3 % of initiator was advisable to use during the ultrasonic assisted radical polymerization to enhance the efficiency without substantially affecting the M; the thickening ability of the product was best under120W ultrasonic frequency power, of which the apparent viscosity attained 153.3 mPa · s as the concentration of U-HAPAM was 0.30 wt.%. Weighting the reaction efficiency and M, the concentration of total monomers was set as 10 % optimally. U-HAPAM achieved more excellent self-assembly performance and the critical association concentration of U-HAPAM prepared under these conditions was 0.27 wt.% (CAC) obtained from apparent viscometry and 0.23 wt.% (CAC') from FS. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The dispersion of reduced graphene oxide (RGO) in polymer matrix was improved. • In situ incorporation of titanate functionalized RGO into polymer was used. • Isopropyl tri(diotylpyrophosphate) titanate (T3) was a good modifier for RGO. • The compatibility and interaction between T3-RGO and polymer were improved. • The one-component coating displayed excellent long-term corrosion resistance. Abstract Achieving a uniform dispersion of reduced graphene oxide (RGO) nanosheets in waterborne polymer matrix remains a challenge. Here, we significantly improved the dispersion stability of RGO in a polymer matrix through functionalizing RGO with titanate coupling agent of different dendritic structure. Titanate coupling agents of two branched dioctylpyrophosphate (T2) and three branched dioctylpyrophosphate (T3) were used. Rather than simply blending graphene with polymer matrix, functionalized graphene (T2-RGO or T3-RGO) was introduced into the reaction system with monomers to participate in the polymerization; resulting in improved compatibility and interaction between the graphene and polymer, especially for T3-RGO. One-component waterborne poly (urethane-acrylate) nanocomposite coatings (WPUA/T2G or WPUA/T3G) were then obtained. The particle size of WPUA/T3G colloidal particle size is much smaller than that of WPUA/T2G, the colloidal stability was also increased with the incorporation of T3-RGO. Compared with pure WPUA, the tensile strength of WPUA/T3G nanocomposite increased from 17.78 MPa to 40.01 MPa, and the elongation at break increased from 249% to 424%. The tensile strength and elongation at break of WPUA/T2G were 32.01 MPa and 366%, which were inferior to that of WPUA/T3G. Moreover, in comparison with pure WPUA, the impedance modulus of WPUA/T3G increased from 1.12 × 105 Ω.cm2 to 1.15 × 108 Ω.cm2, the coating resistance of WPUA/T3G increased from 8.41 × 104 Ω.cm2 to 1.39 × 108 Ω.cm2, which was also much higher than the impedance modulus (6.93 × 106 Ω.cm2) and coating resistance (7.31 × 106 Ω.cm2) of WPUA/T2G. WPUA/T3G nanocomposite coating exhibited excellent long-term corrosion resistance, being superior to the previously reported performance of solventborne polyurethane/graphene composite. [ABSTRACT FROM AUTHOR]

We reported herein the synthesis of block copolymers and their application in the in-situ emulsion polymerization of waterborne poly (urethane-acrylate) (WPUA) nanoemulsions based on phase inversion process. The polymerizable surfmers containing terminal unsaturated double bonds (MSA-r) were successfully synthesized via catalytic chain transfer polymerization (CCTP). Random copolymer (MSA-t) prepared through radical polymerization was utilized as control. The structure, surface tension and aggregation behavior of surfmers were characterized. The phase inversion, formation and stability of WPUA nanoemulsions were systematically investigated. Effects of MSA-r surfmer content and BMA/MMA ratio on the water resistance and thermal stability of the corresponding films were also discussed. It was found that the phase inversion mechanism of PUA prepolymer in the presence of MSA-r surfmers is different from conventional polyurethane prepolymer. The addition of MSA-r and MSA-t surfmers alters the rheological behaviors of PUA prepolymer via PUA-surfmer interactions, as well as the phase inversion process. Compared with WPUA/MSA-t emulsion, WPUA/MSA-r nanoemulsion displayed improved stability at higher solid content. The minimum particle size of WPUA/MSA-r nanoemulsion was 88.7 nm and kept almost constant after 12-month storage, while the particle size of WPUA/MSA-t emulsion was 131.3 nm and increased to 178.9 nm. Moreover, the WPUA/MSA-r film possessed improved water resistance and thermal stability. [ABSTRACT FROM AUTHOR]

Objectives: To find a new appropriate evaluation for urethral plate quality in hypospadias repair, with particular interest in the width proportion of the urethral plate to the glans, serving as an appraisal index. Methods: Data were prospectively collected from prepubertal boys who underwent primary tubularized incised plate hypospadias repair between January 2014 and April 2016 in one center. Intrinsic parameters of the penis (meatal location, glans width, urethral plate width and curvature degree) were measured during the operation. Urethroplasty complications were recorded during follow up. The correlation between width proportion of the urethral plate to the glans and urethroplasty complications was analyzed. Results: Primary tubularized incised plate repair was carried out in 442 patients (mean age 2.8 years, range 0.5–12 years). At mean follow up of 26 months (range 12–38 months), urethroplasty complications occurred in 59 (13.3%) patients. The width proportion of the urethral plate to the glans was weakly correlated to both the glans width and meatal location. The width proportion of the urethral plate to the glans ranged from 0.18 to 0.73, with a mean of 0.39. The cut‐off value of width proportion of the urethral plate to the glans was determined to be 0.36 by the receiver operating characteristic curve. Urethroplasty complications occurred in 17 out of 254 patients (6.7%) with width proportion of the urethral plate to the glans >0.36, and 42 out of 188 patients (22.3%) with width proportion of the urethral plate to the glans ≤0.36. The width proportion of the urethral plate to the glans ≤0.36 showed an increased odds of 4.819‐fold (95% confidence interval 2.548–9.112, P < 0.001) risk of urethroplasty complications compared with width proportion of the urethral plate to the glans >0.36. Midshaft and proximal meatal location also increased the risk of urethroplasty complications. Conclusions: The present study highlights the value of the width proportion of the urethral plate to the glans for objectivity and accuracy in urethral plate evaluation, which in turn serves as an independent factor influencing outcomes in tubularized incised plate repair. [ABSTRACT FROM AUTHOR]

To guarantee the stable and quantitative adding of surfactant into the pressure pipe and not be affected by the inlet and outlet pressure changing, the method utilizing jet pump cavitation characteristics to add surfactant was proposed. Keeping pressure ratio lower than the critical pressure ratio, the adding quantity could remain unchanged. In order to improve the stabilities, reduce the pressure loss and improve the critical pressure ratio of the jet cavitation adding method, a new two-stage cavitation jet adding method and device were proposed, and the performance was investigated experimentally under different working flows and outlet pressures, and compared to the cavitation jet pump in this paper. The results showed that the negative pressure remained unchanged within a certain range of outlet pressure, then decreased gradually with the increase of outlet pressure for the new device, which was similar with the traditional one. Furthermore, the critical pressure ratio of the new device was larger than the traditional one, which indicated that the pressure loss for the new device was smaller and it was more stable as the adding amount of surfactant was constant. In addition, the critical pressure ratio could increase by reducing the additive proportion of surfactant. Based on the above contributions and field investigation, it is believed that the study will play an important role for automatic quantitative control. [ABSTRACT FROM AUTHOR]

The multi walled carbon nanotubes (MWCNTs) were treated with acid mixture (volume ratio of H2SO4 and HNO3 was 3 : 1) to make them carboxylated. And using carboxylated-MWCNTs as fillers, MWC- NTs/PVDF dielectric composites were formed by solution blending into poly(vinylidene fluoride) (PVDF). The structures and morphologies of the materials were characterized by XRD, Raman, TEM and SEM. The effects of the amount of MWCNTs on the thermal stability, mechanical properties and dielectric properties of MWC- NTs/PVDF composites were investigated by using TG, tensile test and LCR impedance analyzer. The result showed that with the increase of carboxylated-MWCNTs content, the thermodynamic and dielectric properties of the composites were significantly improved compared with those of pure PVDF. When m (MWCNTs) was 10%, the mass retention rate of the composites reached 76%. At room temperature and 1 kHz frequency, a per-colation threshold was achieved when m (MWCNTs) was 8%, and the dielectric constant of the composites reached 163.5, which was 16 times of that of the pure PVDF and the dielectric loss was 0.06. At this time, the mechanical properties of the composites were best. The tensile strength, elongation at break and modulus of elasticity were 58.92 MPa, 215.83% and 2 025.42 MPa, respectively. [ABSTRACT FROM AUTHOR]

The aqueous environmental polyurethane/polyacrylate (PUA) microemulsions were obtained through in situ surfactant-free emulsion polymerization exempt of any organic solvents. Hydroxyethyl acrylate (HEA) and pentaerythritol triacrylate (PETA) of different functionalities were adopted as cross-linker to connect polyurethane (PU) and polyacrylate (PA) to obtain PUAH and branched multi-cross-linking PUAP, respectively. It is interesting to note that PUA microemulsion was unstable if no connection was built between PU and PA when in situ surfactant-free emulsion polymerization was adopted, which is different from conventional seed emulsion polymerization. The particle size decreased from 75.27 to 51.24 nm and dispersibility index (DPI) decreased from 0.394 to 0.122 with the increase of vinyl content, and DPI was further decreased with the incorporation of PETA with three vinyl groups at the same vinyl content. Effects of HEA and PETA on the physicochemical properties of PUA films including micromorphology, gel content, surface composition, phase behavior, thermal stability, and water resistance were investigated. TEM and XPS analysis demonstrated that the micromorphology transferred from multi-morphology to single core-shell morphology with PA as the core and PU as the shell and then changed to uniform morphology with homogeneous distribution of PU and PA inside PUAP. High cross-linking density, together with uniform distribution of PU and PA inside PUA system, is beneficial to improve the PUA performance. In addition, the as-prepared microemulsions can be utilized as the surface sizing agent for cellulose fiber paper to greatly increase the physical strength and water resistance. [ABSTRACT FROM AUTHOR]

Stable alkoxysilane-functionalized poly (urethane-acrylate) (IPUASi) VOC-free hybrid microemulsion was successfully prepared through in-situ surfactant-free emulsion polymerization. Two approaches of introducing silane coupling agent (MPTS) were compared. The stability of microemulsion was determined by light scattering technique and rheology. The surface property and morphology were evaluated through X-ray photoelectron spectroscopy and atomic force microscopy. In addition, the static and dynamic mechanical properties, thermal behavior and water resistance of IPUASi films were systematically investigated. When MPTS was introduced during polyurethane prepolymer preparation, slight change took place in the particle size and distribution of IPUASi10 microemulsion even after being stored for a year. And the modulus of IPUASi10 microemulsion kept almost invariable with time at 60 °C. In contrast, when the MPTS was added in the process of water dispersion, the particle size and modulus of IPUASi10A microemulsion greatly increased due to the enhanced instability. Si and C-Si compositions on the surface of IPUASi10A film were much higher than those of IPUASi10 film, and improved phase mixing characteristic nature was detected for IPUASi10, as well as higher mechanical property and water resistance. In the presence of MPTS, the particle size decreased from 95.51 nm to 50.23 nm, the morphology of IPUASi microemulsion transformed from irregular morphology to more uniform globular structure, the interaction between colloidal particles decreased, while the viscoelasticity increased. In addition, the intermolecular interaction was enhanced with increasing MPTS content, resulting in increased mechanical property, thermal property and water resistance. However, excessive MPTS was unfavorable to the performance of IPUASi film. [ABSTRACT FROM AUTHOR]

Cross-linked polyvinyl alcohol (AZ-CIPVA) for effective paper sizing was prepared by using N-(isobutoxymethyl)acrylamide (IBMA) and aziridine cross-linker (AZ) as modifiers. The structure and the performances of the AZ-CIPVA with different dosage of AZ were characterized. The enhancing mechanism of paper sized by AZ-CIPVA was clarified. The results show that cross-linking structure is formed by the reaction between AZ and carboxyl groups in CIPVA molecules. With the increase of AZ content, the gel content, cross-linking density and thermal stability of the AZ-CIPVA film are increased. When the AZ dosage is 3.5%, both tensile strength and modulus of AZ-CIPVA film reach maximum, and the value are 68.34 MPa and 1037.02 MPa, respectively. The water absorption of the film reaches minimum and the folding endurance of the sizing paper reaches maximum when the content of AZ is 2.8%. When applied to the surface of the paper, the maximum dry and wet tensile indexes of the paper are increased by 223.77% and 432.56%, respectively. Roughness of the sizing paper increases slightly and the surface becomes uneven. The micro-structure shows that larger pores between the paper fibers are filled and cross-linked after sizing, which is beneficial to improve the mechanical strength of paper. • A series of cross-linked polyvinyl alcohol (AZ-CIPVA) modified by IBMA and AZ are successfully prepared. • The increasing of AZ can improve the degree of cross-linking and comprehensive performance of both AZ-CIPVA film and sizing paper. • The enhancing mechanism of paper by AZ-CIPVA is proposed. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) has been as an essential gasotransmitter and a potential therapeutic approach for several biomedical treatments such as cardiovascular disorders, hypertension, and other diseases. The endogenous and exogenous H 2 S also plays a crucial role in the bone anabolic process and a protective mechanism in cell signalling. In this study, we have utilized two types of polymers, polycaprolactone (PCL) and gelatin (Gel), for the fabrication of JK-2 (H 2 S donor) loaded nanofibrous scaffold via electrospinning process for bone healing and bone tissue engineering. Comparing the PCL/Gel and PCL/Gel-JK-2 scaffolds, the latter demonstrated enhanced cell adhesion and proliferation capabilities. Furthermore, both experimental scaffolds have been subjected to an in vivo experiment for 4 and 8 weeks in a bone-defect model of a rabbit to determine their biological responses under physiological conditions. There was an obvious increase in bone regeneration in the PCL/Gel-JK-2 group compared to the control and PCL/Gel groups. These results indicate the use of PCL/Gel scaffolds loaded with JK-2 should be considered for possible bone regeneration. Scheme of PCL/Gel-JK-2 fabrication and use for improving the bone formation in vitro and in vivo. [Display omitted] • JK-2, a novel donor of H 2 S, is used to prepare electrospun fibers for the first time. • PCL/Gel-JK-2 shows the best osteoinductive ability in vitro by releasing H 2 S slowly. • PCL/Gel-JK-2 nanofibers effectively enhance the regeneration of skull defect in vivo. [ABSTRACT FROM AUTHOR]

Schematic illustration of the PCL/Gel membrane prepared by co-electrospinning technique for bone tissue engineering. PCL was utilized to provide sufficient mechanical strength for enhancing overall integrity of the membranes. These co-electrospun membranes could slow-release hydrophobic drugs (loading in PCL nanofibers) and controlled-release hydrophilic drugs (loading in Gel nanofibers). In addition, the combination of the natural polymers could enhance the biocompatibility of these membranes and perform their respective functions in the bone healing process. [Display omitted] • PCL and Gel synergistically provide the mechanical properties and bioactivity. • Co-electrospun membrane can slowly release both hydrophilic and hydrophobic drugs. • Regulating PCL content can result in a time-tunable release of hydrophilic drugs. • PCL controls drug release by inhibiting the dissolution/diffusion of Gel fibers. The rising popularity of co-electrospinning technique in the field of biomaterial has enabled the possibility of combining various polymers, in which they provide the mechanical properties and the bioactivity for each other. Herein, a series of polycaprolactone/gelatin (PCL/Gel) composite membranes were prepared by co-electrospinning, and their biocompatibility and drug-controlled release ability were evaluated in detail for the first time. The addition of Gel significantly enhanced the adhesion and differentiation of osteoblasts, while the addition of PCL significantly improved the mechanical properties. Moreover, the in vitro degradation and drug release results showed that by adjust the PCL fibers amount and size, the degradation of Gel and the release profile of hydrophilic drugs/proteins could be effectively controlled: in the low PCL groups (PCL/Gel-1 & PCL/Gel-4), the Gel nano-fibers dissolved rapidly, resulting in an early explosive release within 1 week; however, with the increase of PCL content, the drug release rate decreased gradually, and the total release period could be extended to over 2 weeks (PCL/Gel-2, PCL/Gel-3 & PCL/Gel-5) or more (PCL/Gel-6). Therefore, the preparation of a controllable drug delivery system with good biological activity by co-electrospinning of PCL and Gel could provide an effective strategy for bone regeneration. [ABSTRACT FROM AUTHOR]

The self-assembly of a fluorinated hydrophobically associating polyacrylamide (UFPAM) prepared by emulsifier-free ultrasound-assisted radical polymerization was studied using fluorescence spectroscopy (FS), rheological measurements, and dynamic light scattering (DLS). The effects of the degree of mineralization ( M), temperature, and the concentrations of ionic surfactants-sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB)-on the self-assembly behavior of UFPAM were explored in detail. The results showed that 2,2,3,4,4,4-hexafluorobutyl methacrylate (FA) was effectively incorporated into the UFPAM. As the concentration of UFPAM increased, the hydrophobic self-assembly behavior of UFPAM increased the apparent viscosity and enhanced the structural network of UFPAM, as indicated by the Ostwald-de Waele power-law model, FS, dynamic rheological measurements, and DLS. The maximum apparent viscosity of the UFPAM solution occurred when the polarity of the solution was enhanced in mineralized solution and the polymer coils were expanded at increased temperature. Provided that the concentration of the ionic surfactant was below its CMC, the addition of CTAB promoted the self-assembly of UFPAM, but this did not occur upon the addition of SDS. When the concentration of the surfactant was above the CMC, the aggregation number increased in the UFPAM-CTAB system, whereas it exhibited a minimum value in the UFPAM-SDS system. [ABSTRACT FROM AUTHOR]

Abstract: Solid-state NMR techniques have been employed to investigate the domain structure and mobility of the bacterial biopolymeric metabolites such as poly(3-hydroxybutyrate) (PHB) and its copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 2.7mol% (PHBV2.7) and 6.5mol% (PHBV6.5) 3-hydroxyvalerate. Both single-pulse excitation with magic-angle spinning (SPEMAS) and cross-polarization magic-angle spinning (CPMAS) 13C NMR results showed that these biopolymers were composed of amorphous and crystalline regions having distinct molecular dynamics. Under magic-angle spinning, 1H T 1ρ and 13C T 1 showed two processes for each carbon. Proton relaxation-induced spectral editing (PRISE) techniques allowed the neat separation of the 13C resonances in the crystalline regions from those in the amorphous ones. The proton spin–lattice relaxation time in the tilted rotating frame, , measured using the Lee–Goldburg sequence with frequency modulation (LGFM) as the spin–locking scheme, was also double exponential and significantly longer than 1H T 1ρ . The difference between for the amorphous and crystalline domains was greater than that of 1H T 1ρ . Our results showed that the differences could be exploited in LGFM–CPMAS experiments to separate the signals from two distinct regions. 1H spin-diffusion results showed that the domain size of the mobile components in PHB, PHBV2.7 and PHBV6.5 were about 13, 24 and 36nm whereas the ordered domain sizes were smaller than 76, 65 and 55nm, respectively. The results indicated that the introduction of 3-hydroxyvalerate into PHB led to marked molecular mobility enhancement in the biopolymers. [Copyright &y& Elsevier]

In this study, an anion-cation compound foaming agent (ACFA) was proposed based on the synergistic mechanism, so as to realize efficient production of low-concentration foam for preventing coal spontaneous combustion. The foaming and coal spontaneous combustion prevention properties of ACFA and anion compound foaming agent (AFA) were investigated by using Foamscan and the coal spontaneous combustion testing system, respectively. The results show that foaming speeds of the two agents both increase with the rise of concentration. The critical micelle concentrations of ACFA and AFA are 1‰ and 4‰, respectively. Compared with AFA, ACFA can reach the required foam volume faster. Besides, the foam produced by ACFA can stabilize 115% longer and maintain its effect longer, because ACFA contains more liquid than AFA at the critical micelle concentration. Moreover, the densely and uniformly distributed foam produced by ACFA can more effectively prevent oxygen from feeding the coal. Since coal samples treated with ACFA and AFA both boast high inhibition rates, they can serve as foam fire-extinguishing agents to prevent coal spontaneous combustion in underground mines, but ACFA is more efficient and economical. [ABSTRACT FROM AUTHOR]

Waterborne polyaniline (PANI) dispersion has got extensive attention due to its environmental friendliness and good processability, whereas the storage stability and mechanical property have been the challenge for the waterborne PANI composites. Here we prepare for waterborne PANI dispersion through the chemical graft polymerisation of PANI into epichlorohydrin modified poly (vinyl alcohol) (EPVA). In comparison with waterborne PANI dispersion prepared through physical blend and in situ polymerisation, the storage stability of PANI-g-EPVA dispersion is greatly improved and the dispersion keeps stable for one year. In addition, the as-prepared PANI-g-EPVA film displays more uniform and smooth morphology, as well as enhanced phase compatibility. PANI is homogeneously distributed in the EPVA matrix on the nanoscale. PANI-g-EPVA displays different morphology at different aniline content. The electrical conductivity corresponds to 7.3 S/cm when only 30% PANI is incorporated into the composites, and then increases up to 20.83 S/cm with further increase in the aniline content. Simultaneously, the tensile strength increases from 35 MPa to 64 MPa. The as-prepared PANI-g-EPVA dispersion can be directly used as the conductive ink or coatings for cellulose fibre paper to prepare flexible conductive paper with high conductivity and mechanical property, which is also suitable for large scalable production. [ABSTRACT FROM AUTHOR]