B–OH group was introduced into carbon-based solid acids by the method of low-temperature co‑carbonization. This method also ensures that the solid acid has a high density of –SO3H group. Adsorption kinetics and adsorption thermodynamics of cellobiose on the solid acid were discussed to analyze the adsorption mechanism. And further proved that B–OH group on the solid acid was a strong adsorption site of cellobiose. Therefore, the introduction of B–OH group greatly improved the affinity of the solid acid to cellulose. In addition, boron doping brought a series of positive changes to the structure of solid acid, which all contributed to improving the catalytic activity of solid acid. The hydrolysis activity of the solid acid was increased by 70.34% in comparison with the cellulose-based solid acid.

Conductive hydrogels show broad prospects in wearable electronic devices. However, the conductive hydrogel cross-linked only by chemical bonds has the shortcomings of being hard and brittle, easy to break under pressure. In order to solve these problems, the MPASP-PAA/Fe3+ composite conductive hydrogel is prepared by the method of physical and chemical double crosslinking using modified polyaspartic acid (MPASP) as the chemical crosslinking agent and FeCl3 as the physical crosslinking agent. Compared with traditional chemical crosslinking agents such as N ' N-methylene bisacrylamide, the MPASP can not only increase mechanical properties of the conductive hydrogel, but also improve the biodegradability and biocompatibility. At the same time, FeCl3 as a physical crosslinking agent can also enhance the conductivity and toughness of the conductive hydrogel. When MPASP and Fe3+ content are 2.5 wt% and 0.75 mol%, respectively, the MPASP-PAA/Fe3+ composite conductive hydrogel exhibits high conductivity (0.12 S m(-1)), sensitivity (4.93), and stretchability (329%). In addition, its compressive strength is as high as 1081.39 KPa. The flexible strain sensor assembled by the MPASP-PAA/Fe3+ composite conductive hydrogel can not only monitor human joint movements such as elbow and wrist bending, but also detect subtle vibrations such as vocalization and swallowing.

The present work numerically investigated the effect of catalyst properties on the hydrodynamics of a pilot-scale slurry bubble column reactor with circular sparger and helical heat exchangers by employing the CFD-PBM modeling. Strong dependency on particle size (dp) were observed when dp>75 μm. With the particle size increased, the axial concentration gradient of gas holdup and solid holdup gradually increased, which were not conducive to heat and mass transfer. When dp was in the range of 10–75 μm, the gas holdup increased with increasing the particle size, which is beneficial to the momentum transfer in the bed. The variation of particle density (ρp) had insignificant effect on the overall gas holdup distribution, though the solid holdup increased obviously in the sparger region with ρp increased. This work provides reminding to search for the optimal operating conditions and gives reliable guidelines to prepare high-efficiency catalysts in the synthesis process.

The development of high-temperature proton exchange membrane fuel cells calls for better membrane, and a polyacrylamide/beta-cyclodextrin hydrogel proton exchange membrane is prepared by solution polymerization of beta-cyclodextrin (beta-CD) and acrylamide (Am), for which ammonium persulfate (APS) and N, N ''-(methylene)bisacrylamide (MBA) is used as initiator and crosslinking agent, respectively. The observed proton conductivity of the membrane reaches 12.3 S m(-1) at room temperature, when the ratio of beta-CD, APS, MBA to Am monomer is 0.42 mol%, 0.37 mol%, and 0.14 mol%, respectively, and the primary concentration of doped phosphoric acid is 8 mol L-1. The observed proton conductivity evolution on temperature obeys Arrhenius' law, indicating that the proton conduction mainly follows the hopping mechanism. In addition, the prepared PAM/beta-CD proton exchange membrane has a mass loss of only 8.47% at 205 degrees C, showing good thermal stability compared with PBI membrane. It also has good antioxidative stability as well as promising potential application in high-temperature fuel cells.

以丙烯酰胺为单体(AM)、N,N-亚甲基双丙烯酰胺(MBA)为交联剂,在聚丙烯酰胺/聚吡咯(PAAm/PPy)导电水凝胶中引入聚天冬氨酸(PASP),通过一锅法制备了 PAAm/PPy/PASP复合导电水凝胶,探讨了 PASP对复合导电水凝胶力学性能和导电性能的影响.结果表明,在PAAm/PPy导电水凝胶中引入PASP,不仅能够提高复合水凝胶的导电性能,而且能够显著改善其力学性能.当PASP含量为10％时,所制备的复合导电水凝胶综合性能最好,电导率达到1.19S/m,断裂伸长率由110％提高到了 633％,拉伸强度由55kPa增大到了 117.5kPa;在应变为400％时,灵敏度(GF)可达1.88.将复合导电水凝胶作为应变传感器应用于监测人体运动的研究结果表明,无论是手指弯曲的大应变还是喉咙吞咽的小应变,传感器都表现出较高的灵敏度、稳定性和可重复性.

Flexible electronics have achieved development with the rising consumption of wearable devices. In this work, a novel polyacrylamide-graphene oxide-polyaniline composite hydrogel (PGPH) based flexible electrode with good mechanical and electrochemical properties is prepared. The polyacrylamide interpenetrating network can provide a porous substrate. The strong pi-pi interaction between graphene oxide and polyaniline can stabilize polyaniline. The area-specific capacitance of PGPH is 100.57 mF cm(-2) at a current density of 5 mA cm(-2), and the capacity remains at 75.54% after 1000 cycles. One layer of sodium alginate is spin-coated on top of the electrode to solve the problem of desorption of conductive materials and improve the cycle stability of the materials. The PGPH exhibits a conductivity of 5.11 S m(-1) and elongation at break of 352%, which is significantly higher than that of common polyacrylamide-polyaniline hydrogel. Based on the good mechanical and electrochemical properties of PGPH, it has broad application prospects in flexible energy storage devices and flexible sensors.

High-performance carbon-based solid acid was prepared by a simple method. The effects of carbonization temperature and mixing ratio on the structure and performance of carbon catalysts were explored. The participation of borax increases both -COOH group and -SO3H group densities. In addition, graphitization and specific surface area of the catalyst increase by this co-carbonization method. Higher -COOH group density and aromaticity facilitate the adsorption between catalyst and substrate molecule through hydrogen bonding and CH-pi interaction respectively. These improvements of structural significantly increase the hydrolysis activity of the catalyst.

Bubble/Slurry bubble column reactors (BCR/SBCR) are intensively used as multiphase reactors for a wide range of application in the chemical, biochemical and petrochemical industries. Most of these applications involve complicate gas–liquid/gas–liquid–solid flow behavior and exothermic process, thus it is necessary to equip the BCR/SBCR with heat exchanger tubes to remove the heat and govern the performance of the reactor. Amounts of experimental and numerical studies have been carried out to describe the phenomena taking place in BCR/SBCRs with heat exchanger tubes. Unfortunately, little effort has been put on reviewing the experiments and simulations for examining the effect of internals on the performance and hydrodynamics of BCR/SBCR. The objective of this work is to give a state-of-the-art review of the literature on the effects of heat exchanger tubes with different types and configurations on flow behavior and heat/mass transfer, then provide adequate information and scientific basis for the design and the development of heat exchanger tubes in BCR/SBCR, ultimately provide reasonable suggestions for better comprehend the performance of different heat exchanger tubes on hydrodynamics.

Gas distributors greatly affect the performance of bubble column or slurry bubble column reactors (BCR/SBCRs). Investigation of design parameters characterizing the operation and transport phenomena of gas distributors in BCR/SBCRs can lead to a better understanding of hydrodynamic properties and mass transfer mechanisms. The performance of gas distributors is often described using various mathematical models and computational fluid dynamics simulations supported by experimental research. Nonetheless, little effort has been made to review the effect of the configurations of gas distributors on BCR/SBCR performance. The negative consequences of weeping and uneven gas maldistribution caused by unreasonable design of the distributor were rarely appreciated. This paper reviews the effects of gas distributor configuration on flow behavior and reaction performance. Adequate information about the design and development of gas distributor technology in BCR/SBCRs is provided. Some suggestions for potential research to better comprehend the effects of gas distributor design are put forward.

Stretchable conductive hydrogels are of great significance in wearable electronic devices and tissue engineering scaffolds. In this paper, the zwitterionic polymer network hydrogels are synthesized by radical co-polymerizing acrylic acid (AA) and methyl acryloyl oxygen ethyl trimethyl ammonium chloride (DMC) in aniline (ANI) aqueous solution followed by oxidation polymerization of ANI to form semi-interpenetrating network hydrogel. The conductive hydrogels are endowed excellent mechanical properties by synergistic effect of electrostatic interaction and hydrogen bonding between the interpenetrating network of PANI and P(AA-co-DMC). The tensile strength reaches up to 0.173 MPa at 576% and the compression strength reaches up to 0.73 MPa at 80%. Meanwhile, the zwitterions and polyaniline ensure hydrogels to obtain conductivity (0.428 s m(-1)). In addition, the as-prepared conductive hydrogels can also be used as ionic skin to accurately monitor various movements of the human body, showing its potential applications in wearable devices and flexible electronic devices.

•Impacts of annular gas distributor and circular heat exchanger tube were studied.•Numerical simulations were carried out with a generic CFD-PBM model.•The presence of annular gas distributor induced a stronger circulation flow of slurry.•The circular heat exchanger tube intensifies the bimodal distribution of gas holdup.•An optimum axial location of the gas distributor with enhanced gas holdup was found.

Conductive hydrogels show promising applications in wearable electronic devices. However, it is still challenging to increase the conductivity as well as the mechanical performance of the conductive hydrogels. In addition, it is more challenging to fabricate ultrathin conductive films with good mechanical strength and high transparency. In this study, a metal-free flexible conductive hydrogel for flexible wearable strain sensor with high sensitivity is presented. The conductive hydrogel is prepared by polyvinyl alcohol (PVA) templated polymerizing of polypyrrole (PPy) followed by gelating based on the polymerizing and cross-linking of polyacrylamide (PAAm). The conductive hydrogel is endowed excellent mechanical properties by multiple hydrogen bonds between the interpenetrating network of PVA, PPy, and PAAm. The tensile strength reaches up to 0.2 MPa at 500% and the compression strength reaches up to 1.5 MPa at 90%. It can withstand cyclic loads. The conductivity reaches 0.3 s m(-1) and it is sensitive to stretching and compressing. Therefore, strain sensors are prepared based on such hydrogels to make wearable electronic devices, monitoring the subtle and large strains. It is worth noting that the composite material containing PVA has good film-forming properties. Therefore, ultrathin conductive hydrogel films with high transparency (94.2%), high conductivity (7090 omega/square) and large-area are fabricated at low cost.

Stimuli-responsive hydrogels are attracting extensive attention in drug delivery system. Here, a novel pH, thermo and salt sensitivity of composite hydrogels was synthesized in situ from polysuccinimide modified by γ-aminopropyltriethoxysilane with mesoporous molecular sieves (MCM-41) as only crosslinking agent for controlled salicylic acid release. Morphologies and thermal behaviors of KPAsp/MCM-41 hydrogels were characterized by scanning electron microscopy and thermogravimetric analysis. Swelling dynamic behaviors, pH, thermo and salt sensitivities and drug releasing capacities of composite hydrogels were also systematically investigated. The obtained results show that multi-responsive hydrogels are very sensitive to environmental pH, external temperature and ionic valence, which indicated that the MCM-41 addition not only can ameliorate the network structure, but also can enhance the drug loading and releasing capacity. The controlled salicylic acid release rates of MCM-41/KPAsp hydrogels can reach to 33.6% and 61.2% in simulated gastric fluid (pH = 1.2) and in simulated intestinal fluid at (pH = 7.4) at 37 °C, respectively. The as-synthesized multi-responsive hydrogels reported here are promising candidates for application in targeted drug delivery system.

The environmentally friendly polycarboxylate superplasticizer based on modified poly(aspartic acid) (MPASPs) with varied grafting densities were prepared by partially ring-opening reaction of polysuccinimide (PSI) with polyetheramine M2005 (PEM) and sodium p-aminobenzenesulfonate (SPA) and subsequently hydrolyzing of the remaining imide ring under mildly alkaline conditions. FTIR was used to characterize the MPASPs. The properties of the MPASPs were evaluated by fluidity of cement paste, flexural strength of hardened cement mortar, adsorption amount on cement particle surface, zeta potential of cement paste, XRD and TG-DSC analysis. The results revealed that the MPASPs with proper incorporation of polyether side chains and benzene sulfonic acid groups could improve the fluidity of cement paste and the mechanical property of cement mortar. The fluidity of cement paste doped with MPASP-3 was 197% higher than that of PASP, and the cement mortar with MPASP-3 shown the highest flexural strength at both ages of 7 d and 28 d. The MPASPs could inhibit the early cement hydration while had little effect on later cement hydration. Based on the above results, the dispersion model of MPASPs in cement-water system was also discussed. This study offered a novel environmentally friendly superplasticizer based on a biodegradable green polymer and simple synthesis method. (C) 2019 Elsevier Ltd. All rights reserved.

Polymeric complexes formed between poly(4‐vinylphenol) (PVPh) and poly(4‐vinylphyridine) (PVP) at small molar ratio based on hydrogen bond in ethanol were found to undergo a long “aging” process during storage, which composed of two different stages. In Stage 1, the intra‐complex reorganization occurred and the size of the complexes enlarged gradually. And in Stage 2, the aggregation between complexes particles occurred and made the size of the complexes enlarge more quickly. This “aging” process could last for 80 days even though the polymeric complexes precipitated in the end like others. The effect of “aging” time on the Layer‐by‐Layer assembly behavior of the complexes was also investigated. The assembly behavior of the complexes might change from linear growth to exponential growth by simply prolonging the “aging” time of the complexes and two extremely different structures were obtained. POLYM. ENG. SCI., 59:E394–E402, 2019. © 2018 Society of Plastics Engineers

以聚天冬氨酸(PASP)与壳聚糖季铵盐(HTCC)为基元,运用层层组装技术制备了可以释放双药物的层层组装聚合物膜.通过先采用浸泡的形式负载盐酸柔红霉素(DNR)并喷涂阻隔层,再将盐酸万古霉素(VAN)以复合物PASP-VAN的形式与HTCC层层组装的方法,实现了DNR与VAN在膜中的共同负载.探讨了阻隔层的周期数对VAN与DNR释放效果的影响,结果表明,阻隔层可以延缓VAN与DNR的释放速率,VAN与DNR在生理盐水中的释放时间分别持续1680min和2700min,累积释放量分别为2.26mg和0.20mg.

以聚琥珀酰亚胺(PSI)和端氨基聚醚(M2005)为原料,合成了聚醚改性聚天冬氨酸减水剂(PEMPASP),采用FTIR对PEMPASP进行了结构表征,考察了不同减水剂及其用量对水泥净浆流动度和胶砂强度的影响;通过对TOC、Zeta电位、XRD以及TG-DSC分析,分析了PEMPASP减水剂的作用机理.结果表明:当n(PSI):n(M2005)=1:0.14、PEMPASP掺量为水泥质量的0.35％时,水泥的净浆比掺加聚天冬氨酸(PASP)的水泥净浆流动度提高了189％,在PEMPASP质量分数为水泥的0.25％时,水泥胶砂抗折强度比空白水泥增长了15.6％,比含有PASP的水泥胶砂增长了17％;由于在PASP分子链上引入长侧链聚醚链,改变了减水剂分子上的电荷密度和侧链结构,影响了减水剂对水泥颗粒的静电作用和位阻作用,进而改善了吸附、分散以及水泥的水化作用,提高了减水剂的综合性能.

ABSTRACT In this work, modified attapulgite/poly(aspartic acid) (MATP/PAsp) composite superabsorbent resin with 3-D network structure was prepared by the method of solution polymerization, wherein we used polysuccinimide(PSI) as interdiemate, attapulgite (ATP) as the filling material, γ-aminopropyl triethoxysilane (KH-550) as the modifier, and 1,6-hexamethylenediamine as the crosslinking agent. For further identification of microstructures of this resin, transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were adopted. Influences of the particle size, addition, and modification time on the absorbency performances of resin were investigated respectively. It was found that there is a significant improvement in micro structure with the introduction of MATP, and the water absorbency and retention performance were also increased. The optimum MATP/PAsp composite resin was obtained under condition of particle size range of 45 µm-54 µm, addition dopant of 2wt%, modification time of 6.5 h. The swelling ratio of composite resin in distilled water and normal saline were 892 g g−1 and 95 g g−1, respectively, which had 23% and 30% increase compared the case of none-composite resin samples. The water-retention rate for composite resin was measured to be 66.12% after 6 h's constant temperature drying at 50℃, which is higher by 7.72% than none-composite resin.

A modified polyaspartic acid/polyvinyl alcohol interpenetrating network (KPAsp/PVA IPN) absorbent resin is synthesized by one-step interpenetrating method in aqueous system using polysuccinimide grafted 3-aminpropyltriethoxysilane (KH-550) and polyvinyl alcohol as raw materials.The sensitivities of KPAsp/PVA IPN absorbent resin on pH and temperature are investigated.The results show this resin has good sensitive to temperature and exhibits the highest water absorbency at 40℃.The resin demonstrates pH sensitivity in a pH range of 2-12 and the swelling ratio achieves a maximum value when pH is 4 and 9,respectively.The resin's thermal stability is analyzed by TGA and its structure and surface morphology are characterized by SEM and FT-IR.

基于层层组装技术,制备了能够长效释放抗癌药物甲氨蝶呤(MTX)的层层组装膜.分别通过聚天冬氨酸(PASP)和聚烯丙基胺盐酸盐-甲氨蝶呤(PAH-MTX)复合物基于静电作用的层层组装负载,以及先制备空白膜再后扩散负载这两种方法完成了MTX的膜内负载.层层组装负载中,聚电解质浓度增大则MTX负载量增多,当复合物pH=7.5时MTX的负载量较高且可持续释放36h.后扩散负载中,PASP-PAH/PAH空白膜与PASP/PAH及PASP/PAH-PASP空白膜相比,更有利于MTX的后扩散负载.后扩散负载与层层组装负载相比,药物负载量增多,但缓释时间降低.该研究为药物负载及缓释材料的制备提供了参考.