聚乙烯亚胺修饰碳纤维对环氧树脂复合材料性能的影响

为提高碳纤维与环氧树脂的界面结合性能,从而提高复合材料的摩擦学性能,用聚多巴胺和聚乙烯亚胺对碳纤维进行表面修饰,利用光谱分析仪和扫描电子显微镜分析修饰前后碳纤维表面的化学组成和微观结构,利用万能材料试验机和摩擦磨损试验机考察碳纤维增强环氧树脂复合材料的力学性能和摩擦学性能。结果表明：碳纤维经表面处理之后的粗糙程度和活性官能团增多,改善了纤维与树脂之间的界面结合,使得复合材料的弯曲强度和拉伸强度得到不同程度的提高;与未修饰碳纤维增强的环氧树脂复合材料相比,表面修饰碳纤维增强环氧树脂复合材料的耐磨性能得到了很大程度的提高,复合材料的磨损机制也由疲劳磨损转变为磨粒磨损。     

Development of silica‐gel‐supported polyethylenimine sorbents for CO2 capture from flue gas

In order to reduce the sorbent preparation cost and improve its volume‐based sorption capacity, the use of an inexpensive and commercially available silica gel was explored as a support to prepare a solid polyethylenimine sorbent (PEI/SG) for CO₂ capture from flue gas. The effects of the pore volume and particle size of the silica gels, molecular weight of polyethylenimine and amount of polyethylenimine loaded, sorption temperature and moisture in the flue gas on the CO₂ sorption capacity of PEI/SG were examined. The sorption performance of the developed PEI/SG was evaluated by using a thermogravimetric analyzer and a fixed‐bed flow sorption system in comparison with the SBA‐15‐supported polyethylenimine sorbent (PEI/SBA‐15). The best PEI/SG sorbent showed a mass‐based CO₂ sorption capacity of 138 mg‐CO₂/g‐sorbent, which is almost the same as that of PEI/SBA‐15. In addition, the PEI/SG gave a high volume‐based sorption capacity of 83 mg‐CO₂/cm³‐sorbent, which is higher than that of PEI/SBA‐15 by a factor of 2.6. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2495–2502, 2012     

Construction of functional aliphatic polycarbonates for biomedical applications

Aliphatic polycarbonates are one important kind of biodegradable polymers and have been commonly used as integral components of engineered tissues, medical devices and drug delivery systems. As far as the biomedical application is concerned, traditional aliphatic polycarbonates usually suffer from the strong hydrophobicity, deficient functionality, and insufficient compatibility with cell/organs. Consequently, the application is quite limited in scope. Due to the imparted appealing properties, aliphatic polycarbonates bearing specifically designed functional/reactive groups attract great interest from researchers in the recent years. The present review outlines the development up to date concerning the design and biomedical application of functional aliphatic polycarbonates, with an emphasis on their ring-opening (co)polymerization preparation.     

Cellulose-based formaldehyde adsorbents with large capacities: Efficient use of polyethylenimine for graphene oxide stabilization in alkaline–urea system

A cellulose-based polyethylenimine modified graphene oxide (PEI-GO) composite aerogel is fabricated through the alkaline–urea aqueous system. Inspired from the performance of nanocarriers in gene delivery, this article proposes a pathway to disperse GO in the green environment with strong electrolyte concentrations via the decorated branched PEI. The entire aqueous system shows good miscibility and stability. Meanwhile, the dynamic light scattering results indicate that PEI-GO and cellulose chains become entangled to form a new supramolecular complex in the alkaline–urea solution, and a “hand” model is devised accordingly. The efficient dispersion of PEI-GO (1–0.1%) over the entire cellulose support structure (3%) enables the resultant aerogel to exhibit a gaseous formaldehyde adsorption capacity, that is, 8.51 times greater than the pure cellulose aerogel under ambient temperatures. This dual function opens up enormous opportunities to process cellulose-based GO materials in this green and inexpensive solvent with strong electrolyte concentrations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47860.     

Hydrogen storage properties of highly cross-linked polymers derived from chlorinated polypropylene and polyethylenimine

Highly cross-linked polymer derived from chlorinated polypropylene (CPP) grafted with polyethylenimine (PEI) was synthesized by hydrothermal amination reaction. The influence of different reaction conditions on the structure and properties of highly cross-linked polymer was investigated. The structures of the polymers named CPP-g-PEI were characterized by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (EA), ¹³C solid-state NMR (¹³C NMR), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscope (TEM), powder X-ray diffraction (PXRD) and nitrogen sorption technique. CPP-g-PEI had honeycomb-like pores with an average size of between 5.37 and 13.54 nm and was thermally stable up to 250 °C. CPP-g-PEI was amorphous porous polymer with some spherulites. The N content of CPP-g-PEI increased and the Cl content of CPP-g-PEI decreased after hydrothermal amination reaction. The hydrogen storage properties of different CPP-g-PEI samples were determined by a hydrogen storage analyzer. Among all samples, hydrogen storage capacity of CPP-g-PEI at 100 °C and triethylamine solvent (CPP-g-PEI-2) achieved the highest hydrogen uptake 11.26 wt% at 77 K, 5 MPa. In addition, OH⁻ type CPP-g-PEI (CPP-g-PEI_OH−) exhibited a hydrogen uptake of 2.47 wt% at 300 K, 5 MPa. BET specific surface area of the sample was not directly associated with hydrogen storage capacity. Hydrogen adsorption enthalpy of CPP-g-PEI-2 was calculated by the Arrhenius equation to be 38.79 kJ/mol and the adsorption process of CPP-g-PEI was investigated to be reversible physical adsorption.     

Photothermally Controlled Gene Delivery by Reduced Graphene Oxide–Polyethylenimine Nanocomposite

Externally stimuli‐triggered spatially and temporally controlled gene delivery can play a pivotal role in achieving targeted gene delivery with maximized therapeutic efficacy. In this study, a photothermally controlled gene delivery carrier is developed by conjugating low molecular‐weight branched polyethylenimine (BPEI) and reduced graphene oxide (rGO) via a hydrophilic polyethylene glycol (PEG) spacer. This PEG–BPEI–rGO nanocomposite forms a stable nano‐sized complex with plasmid DNA (pDNA), as confirmed by physicochemical studies. For the in vitro gene transfection study, PEG–BPEI–rGO shows a higher gene transfection efficiency without observable cytotoxicity compared to unmodified controls in PC‐3 and NIH/3T3 cells. Moreover, the PEG–BPEI–rGO nanocomposite demonstrates an enhanced gene transfection efficiency upon NIR irradiation, which is attributed to accelerated endosomal escape of polyplexes augmented by locally induced heat. The endosomal escaping effect of the nanocomposite is investigated using Bafilomycin A1, a proton sponge effect inhibitor. The developed photothermally controlled gene carrier has the potential for spatial and temporal site‐specific gene delivery.     

Innovative Strategy for MicroRNA Delivery in Human Mesenchymal Stem Cells via Magnetic Nanoparticles

Bone marrow derived human mesenchymal stem cells (hMSCs) show promising potential in regeneration of defective tissue. Recently, gene silencing strategies using microRNAs (miR) emerged with the aim to expand the therapeutic potential of hMSCs. However, researchers are still searching for effective miR delivery methods for clinical applications. Therefore, we aimed to develop a technique to efficiently deliver miR into hMSCs with the help of a magnetic non-viral vector based on cationic polymer polyethylenimine (PEI) bound to iron oxide magnetic nanoparticles (MNP). We tested different magnetic complex compositions and determined uptake efficiency and cytotoxicity by flow cytometry. Additionally, we monitored the release, processing and functionality of delivered miR-335 with confocal laser scanning microscopy, real-time PCR and live cell imaging, respectively. On this basis, we established parameters for construction of magnetic non-viral vectors with optimized uptake efficiency (~75%) and moderate cytotoxicity in hMSCs. Furthermore, we observed a better transfection performance of magnetic complexes compared to PEI complexes 72 h after transfection. We conclude that MNP-mediated transfection provides a long term effect beneficial for successful genetic modification of stem cells. Hence, our findings may become of great importance for future in vivo applications.     

Biodegradable synthetic polymers: Preparation, functionalization and biomedical application

Biodegradable polymers have been widely used and have greatly promoted the development of biomedical fields because of their biocompatibility and biodegradability. The development of biotechnology and medical technology has set higher requirements for biomedical materials. Novel biodegradable polymers with specific properties are in great demand. Biodegradable polymers can be classified as natural or synthetic polymers according to the source. Synthetic biodegradable polymers have found more versatile and diverse biomedical applications owing to their tailorable designs or modifications. This review presents a comprehensive introduction to various types of synthetic biodegradable polymers with reactive groups and bioactive groups, and further describes their structure, preparation procedures and properties. The focus is on advances in the past decade in functionalization and responsive strategies of biodegradable polymers and their biomedical applications. The possible future developments of the materials are also discussed.     

Xanthate‐mediated polymerization of styrene on hyperbranched polyethylenimine: Synthesis,characterization, and guest‐encapsulating property

Hyperbranched polyethylenimine (HPEI) is a highly polar, multifunctional polymer bearing active amines throughout its globular structure. In this article, the amino protons, which were incompatible with living radical polymerization techniques, were alkylated with propylene oxide, leading to tertiary amines and hydroxyls, and part of the hydroxyl groups were further transformed into xanthate groups. The HPEI‐xanthate could mediate the polymerization of styrene, leading to a star‐like, multiarm amphiphilic polymer. It was found that the polymerization was a hybrid of living and conventional radical processes. The resulting amphiphilic, core‐shell‐structured polymer existed as a unimolecular micelle (UIM) in apolar solvent and could irreversibly encapsulate water‐soluble anionic dyes. At high pH, the encapsulated dyes could be partly released. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetics and equilibrium of cobalt ion adsorption on cross‐linked polyethylenimine membrane

The kinetics and equilibrium of cobalt ion adsorption on crosslinked polyethylenimine (PEI) membrane were studied by the spectroscopic method in terms of time, cobalt ion concentration, and temperature. It was found that the adsorption of cobalt ion on crosslinked PEI membrane obeyed the pseudofirst‐order kinetic model and the equilibrium adsorption amount of cobalt ion on crosslinked PEI membrane was closely related to the initial cobalt ion concentration. The equilibrium adsorption amount increased with the decrease of temperature and obeyed a Langmuir isotherm to give the equilibrium constant for the adsorption of cobalt ion on crosslinked PEI membrane under various temperatures. Based on Van't Hoff equation the enthalpy and entropy of the adsorption of cobalt ion on crosslinked PEI membrane were determined to be ?12.9 kJ mol^?1 and ?107 J mol^?1 K^?1, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007