Preparation,characterization, and properties of disulfide-containing polyethyleneimine grafted carbon nanotubes

Novel functionalized carbon nanotubes (CNTs) were prepared by grafting disulfide-containing polyethyleneimine (SSPEI) to CNTs. The SSPEI were synthesized by Michael addition between cystamine bisacrylamide and low molecular weight branched 1.8 kDa PEI. Three SSPEI grafted carbon nanotubes (CNTs-SSPEI) were successfully prepared through grafting SSPEI to CNTs. The grafted ratios were 32.26%, 43.11%, and 51.50%, respectively. Moreover, the grafted ratio could be tuned by adjusting the CNTs/SSPEI ratio during the process of preparation. The CNTs-SSPEI was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The CNTs-SSPEI showed better dispersability and stability in water than CNTs. In addition, the SSPEI on the surface of CNTs-SSPEI could be degraded in the presence of dithiothreitol.     

Very fast H2 production from the methanolysis of NaBH4 by metal‐free poly(ethylene imine) microgel catalysts

The polyethyleneimine (PEI) microgels prepared via microemulsion polymerization are protonated by hydrochloric acid treatment (p‐PEI) and quaternized (q‐PEI) via modification reaction with methyl iodide and with bromo alkanes of different alkyl chain lengths such as 1‐bromoethane, 1‐bromobutane, 1‐bromohexane, and 1‐bromooctane. The bare p‐PEI and q‐PEI microgels are used as catalysts directly without any metal nanoparticles for the methanolysis reaction of sodium borohydride (NaBH₄). Various parameters such as the protonation/quaternization reaction on PEI microgels, the amount of catalyst, the amount of NaBH₄, and temperature are investigated for their effects on the hydrogen (H₂) production rate. The reaction of self‐methanolysis of NaBH₄ finishes in about 32.5 min, whereas the bare PEI microgel as catalyst finishes the methanolysis of NaBH₄ in 22 min. Surprisingly, it is found that when the protonated PEI microgels are used as catalyst, the same methanolysis of NaBH₄ is finished in 1.5 min. The highest H₂ generation rate value is observed for protonated PEI microgels (10 mg) with 8013 mL of H₂/(g of catalyst.min) for the methanolysis of NaBH₄. Moreover, activation parameters are also calculated with activation energy value of 23.7 kJ/mol, enthalpy 20.9 kJ/mol, and entropy ?158 J/K.mol. Copyright © 2016 John Wiley & Sons, Ltd.     

Estimation of Binding Constants of Cd(II), Ni(II) and Zn(II) with Polyethyleneimine (PEI) by Polymer Enhanced Ultrafiltration (PEUF) Technique

Abstract

Continuous and batch processes of polymer enhanced ultrafiltration for the estimation of binding constants of divalent cadmium, nickel, and zinc ions have been elaborated. Polyethyleneimine was used as a complexation agent. Effect of pH and ionic strength on the binding ability of target metal ions to polyethyleneimine were estimated by continuous mode PEUF system. A mathematical model was developed to estimate apparent complexation constants of metal ions with PEI. The development of this model, which is in good agreement with experimental data, enables to compare the data obtained in both continuous and batch system and correlate the effect of pH and ionic strength with apparent binding constants.     

聚乙烯亚胺包埋无色纳米银抗菌剂制备及协同抗菌效果研究

以高枝化聚乙烯亚胺(PEI)为稳定剂,硼氢化钠为还原剂,利用化学还原法制备了纳米银抗菌剂。探讨了温度、PEI与Ag+的摩尔比对纳米银抗菌剂合成的影响,利用紫外分光光度法及扫描电镜对合成纳米银抗菌剂进行了表征,利用抑菌圈实验分别对纳米银及PEI进行了抑菌性能测试,筛选出稳定性好抑菌性强的纳米银抗菌剂制备工艺。实验结果表明,在45℃,PEI与Ag+的摩尔配比在2∶1~0.6∶1条件下能制备无色透明且抑菌性强的具有核壳结构的纳米银抗菌剂,PEI对纳米银抗菌剂具有协同作用。     

自交联季铵化聚乙烯亚胺纸张增湿强剂的制备及应用

利用2,3-环氧丙基三甲基氯化铵（GTA）和γ-缩水甘油醚氧丙基三甲氧基硅烷（KH560）对聚乙烯亚胺（PEI）进行改性,制得自交联季铵化聚乙烯亚胺（MPEI）。结果表明,最佳制备条件（GTA和KH560质量分数分别为2%和1%（相对于PEI总质量）、反应温度50℃、反应时间3 h）下制得的MPEI固含量为12%、黏度为482.1 mPa·s、平均粒径为119.6 nm,稳定性良好,室温下放置90天无凝胶现象。利用傅里叶变换红外光谱（FT-IR）仪、热重分析（TG）仪、黏度仪、粒径分析仪及溶液稳定性分析仪等对MPEI进行结构和性能表征,探讨不同GTA质量分数的MPEI对纸张物理性能的影响,并利用扫描电子显微镜（SEM）观察纸张表面形貌。结果表明,向纸浆内添加质量分数为1.6%（相对于绝干浆质量）的MPEI并进行抄纸,与原纸相比,MPEI纸张的干抗张指数、湿抗张指数、耐折度和撕裂指数分别提高了34%、300%、515%和12%。本课题制得的MPEI不含有机氯,是一种新型环保的纸张增湿强剂。     

废涂布纸回用过程中胶黏物的分析和控制

以真空镀铝原纸为原料制备废涂布纸浆,通过SEM、红外光谱、电荷需求量等表征手段,研究了大胶黏物、微胶黏物和DCS(溶解和胶体物质)的来源、形态、成分、阴离子垃圾贡献率。结果表明,丁苯胶乳是胶黏物的主要来源,大胶黏物包覆颜料形成大胶黏物混合物,碳酸钙对微胶黏物吸附沉积,而DCS稳定分散于白水中,具有最大的阴离子垃圾贡献率。大胶黏物可通过纸张抄造脱离白水,而微胶黏物和DCS可通过添加0.2%用量的阳离子聚乙烯亚胺进行控制,具有较好的效果。     

Direct coagulation casting of silicon carbide suspension via polyelectrolyte dispersant crosslink reaction

A direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5-6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively.     

An approach to textile dye removal using sawdust from Aspidosperma polyneuron

The textile industry is responsible for discarding wastewater contaminated with dyes. The timber industry generates waste in the form of sawdust. The aim of the present study was to evaluate the adsorptive potential of sawdust obtained from the Aspidosperma polyneuron tree for the removal of the textile dye from wastewater. Sawdust was subjected to different pre-treatments (acid, alkaline and polyethyleneimine) in order to increase its adsorption capacity. Based on the results from the isotherms, treatment with polyethyleneimine (PEI) led to the greatest adsorption capacity and fits the Freundlich model, indicating cooperative adsorption. Other treatments with sawdust best fit the Langmuir model, but the untreated sawdust presented better results than the treated sawdust. These results were only surpassed by sawdust treated with PEI. A. polyneuron revealed good potential for use as an adsorbent to remove dyes, which is a novel result, since to date there is no study on its use as a sorbent material.     

Polymer brush coatings for combating marine biofouling

A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides. This review summarizes recent developments in marine antifouling polymer brushes and coatings that are tethered to material surfaces and do not actively release biocides. Polymer brush coatings have been designed to inhibit molecular fouling, microfouling and macrofouling through incorporation or inclusion of multiple functionalities. Hydrophilic polymers, such as poly(ethylene glycol), hydrogels, zwitterionic polymers and polysaccharides, resist attachment of marine organisms effectively due to extensive hydration. Fouling release polymer coatings, based on fluoropolymers and poly(dimethylsiloxane) elastomers, minimize adhesion between marine organisms and material surfaces, leading to easy removal of biofoulants. Polycationic coatings are effective in reducing marine biofouling partly because of their good bactericidal properties. Recent advances in controlled radical polymerization and click chemistry have also allowed better molecular design and engineering of multifunctional brush coatings for improved antifouling efficacies.     

聚乙烯亚胺氨基化磁性氧化石墨烯的制备及其对活性艳红X-3B的吸附

使用改性hummers法制备出氧化石墨烯(GO),通过水热法在GO上生长磁性CoFe₂O₄,再使用聚乙烯亚胺(PEI)进行氨基改性,制备出聚乙烯亚胺氨基化磁性氧化石墨烯(PEI-MGO)。使用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对PEI-MGO的结构和微观形貌进行表征。结果表明:纳米级尖晶石相CoFe₂O₄均匀分散于GO上,且氨基改性成功。探讨了PEI-MGO对水体中活性艳红X-3B的吸附性能。结果表明:在活性艳红X-3B初始质量浓度为150mg/L、体积为100mL、吸附剂质量为0.04g、pH值为1、吸附时间为60min时达到平衡,平衡吸附量为361.15mg/g。PEI-MGO对活性艳红X-3B的饱和吸附量为470.58mg/g。磁分离和磁回收研究表明,PEI-MGO能快速从水体中分离,回收率为98.6%。