磁性高分子微球

磁性高分子微球由高分子化合物(或聚合物)与无机磁性物质两部分复合而成,其性质依赖于无机磁性物质、高分子化合物的性质及其复合机制,特别是不同的磁性物质展示出的磁性质多种多样。以磁性金属或其氧化物为核、高分子化合物或聚合物为壳层的磁性微球,     

高分子磁性微球的研究进展

综述了磁性高分子微球的最新研究进展,并介绍了高分子磁性微球制备方法中比较经典的几种,并比较了他们各自的优势和不足。并对高分子磁性微球的研究方向的未来发展进行了展望。     

磁性高分子微球的制备及其在生物医学上的应用

综述了磁性高分子微球的组成、分类及制备方法,介绍了其在生物医学方面的应用。     

磁性高分子微球的制备及其应用

介绍了有机高分子与磁性氧化铁复合的制备方法,总结了磁性高分子微球在废水处理、生物工程方面的应用,并对其发展趋势做了展望。     

大粒径磁性高分子微球的合成

本文研究了苯乙烯，丙烯酸等单体在磁性氧化铁的醇／水分散体系中的聚合行为。为了改善磁性氧化铁粒子与苯乙烯单体间的亲合性，加入聚乙二醇作为发散剂和稳定剂，制备出业径为３０－１０００μｍ的具有磁响应性的聚苯乙烯微球。     

磁性高分子微球的研究进展及生物医学应用

磁性高分子微球由于具有磁性和功能性基团,在许多领域尤其是细胞生物学、生物医学等领域具有广阔的应用前景。本文综述了磁性高分子微球的制备及生物医学应用等方面的研究进展。     

磁性高分子微球制备研究进展

磁性高分子微球作为一种新型功能材料,具有强磁响应性、易生物降解、生物相容性好、无毒、可通过其他手段进行友好改性等特性。介绍了近年来磁性高分子微球的制备方法,对各种方法进行了简要分析,指出不同的制备方法可以制备出具有不同性能的磁性高分子微球。最后对磁性高分子微球的制备方法的发展趋势进行了展望。     

磁性微球的应用研究进展

介绍了磁性高分子微球在废水处理、固定化酶、药物载体、细胞分离等方面的应用,并对磁性高分子微球的发展趋势进行了展望。     

磁性高分子复合微球去除重金属的研究进展

磁性高分子复合微球是近年来受到广泛关注的新型功能材料。本文介绍了磁性高分子复合微球的制备、特性、结构和组成。综述了磁性高分子复合微球及改性后的磁性高分子复合微球对水处理中重金属的去除研究,并对磁性高分子复合微球对重金属处理的研究进展做了总结与展望。     

磁性微球的制备

在总结近年来国内外有关磁性微球研究成果的基础上,对磁性微球进行了分类,着重对高分子磁性微球的几种主要制备方法和工艺过程进行了概述.     

《生物高分子材料》教学改革的思考

针对材料学专业课程《生物高分子材料》的教学特点,从激发学生的学习兴趣、丰富教学手段、充实教学内容、启发学生发散思维和改革考核方式等方面进行了一些探索和尝试。以期切实提高学生的创新与实践能力,满足现代社会对大学创新型、创业型的双创型人才培养需求。     

反应条件对合成单分散二氧化硅微球的影响

采用正硅酸乙酯、氨水、异丙醇和水为原料,合成了微米和亚微米级二氧化硅微球,着重研究了实验温度、氨水浓度、正硅酸乙酯的用量、加水量以及反应时间对该反应的影响。结合对所合成产物的扫描电镜表征,确定了制备不同粒径、均匀的单分散二氧化硅微球的实验条件。     

PP/微球复合材料的发泡行为及力学性能

选用PP(EPS30R)、PP(K9928)为基体材料,分别加入EK405、EK406微球母粒,在二次开模条件下制备微发泡PP/微球复合材料,研究不同特性树脂和微球母粒对PP/微球复合材料发泡行为及力学性能的影响规律。结果表明:微球母粒EK406适合于PP/膨胀微球复合材料的发泡,发泡倍率达12%,泡孔平均直径和泡孔密度分别为29.94μm、7.93×106个/cm3,能够获得泡孔细小、均匀而致密的微发泡聚丙烯材料。熔体指数低的PP材料适合于微球发泡,发泡质量较好,综合性能理想,拉伸和冲击强度分别为18.52 MPa、13.18 kJ/m2,比强度达到23.03。     

Biopolymer gelation- exponents and critical exponents

Summary The gelation of biopolymer systems has been studied, at least, empirically for many years, but only more recently have the methods of macromolecular science been applied. A number of following studies have tended to concentrate on measuring power law exponents, and have ignored details of the network structure. Biopolymer physical gels are more complicated than “simple” chemically crosslinked systems, which means that approaches designed, for example, for crosslinked melts have to be applied with caution. Consequently, while measuring exponents alone can give some valuable information, and some apparent “universalities” are seen, the details of pre-exponential factors can often prove more significant and useful. In this article we re-examine the mapping of generalised percolation parameters (for example p, p_c) unto either a time or a concentration axis. In this we consider the assumptions behind such an approach, and the applicability of critical exponent treatments in a regime that is typically a long way away from critical, at least when judged in terms of absolute (Ginzburg) criteria.     

The Moisture Migration Behavior of Plasticized Starch Biopolymer

Using plasticized starch pellets as a precursor for making thermoformed products is a commercially viable and profitable idea. However, drying of plasticized starch is quite complex in nature, partly due to the synergistic interactions between starch and plasticizers in the presence of water. The migration of water from starch pellets plasticized by two components, glycerol and xylitol, at three different temperatures was investigated in the present work. Evidence for synergistic interaction between plasticizers and water within starch is shown by the reduced effective moisture diffusivities and moisture migration fluxes at different overall plasticizer concentrations. In addition, the effective moisture diffusivities showed stronger dependence on moisture concentration and the plasticizer molecular weight even though the moisture flux was comparable. The drying process was characterized by two effective diffusion coefficients (D ₁, D ₂) and, interestingly, the coefficients were an order of significance apart. The Peleg model was investigated for predicting the drying behavior and it is shown that the Peleg constants k ₁ and k ₂ increase with temperature. k ₂, Which is related to material structure and morphology, showed comparable modification by addition of plasticizers, indicating that plasticizers were able to modify the fundamental structure, and xylitol showed greater average k ₂ values than glycerol. Further, because k ₁ is related with moisture diffusivity, the effect of temperature on diffusivity was interpreted using the Arrhenius relationship. The activation energy values confirm that plasticizers can lock in water within the new structure. Overall, the larger structure of xylitol showed better stability in controlling moisture diffusivities and migration fluxes. These findings can provide better insights in designing and controlling the vapor barrier properties of starch-based packaging materials.     

Small AgNP in the Biopolymer Nanocomposite System

In this work, ultra-small and stable silver nanoparticles (AgNP) on chitosan biopolymer (BP/AgP) were prepared by in situ reduction of the diamminesilver(I) complex ([Ag(NH₃)₂]⁺) to create a biostatic membrane system. The small AgNP (3 nm) as a stable source of silver ions, their crystal form, and homogeneous distribution in the whole solid membrane were confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The X-ray photoelectron spectroscopy (XPS) and Auger analysis were applied to investigate the elemental composition, concentration, and chemical state of surface atoms. It was found that ultra-small metallic nanoparticles might form a steady source of silver ions and enhance the biostatic properties of solid membranes. Ultra-small AgNP with disturbed electronic structure and plasmonic properties may generate interaction between amine groups of the biopolymer for improving the homogeneity of the nanometallic layer. In this work, the significant differences between the typical way (deposition of ex-situ-prepared AgNP) and the proposed in-situ synthesis approach were determined. The improved thermal stability (by thermogravimetry and differential scanning calorimetry (TG/DSC) analysis) for BP/AgP was observed and explained by the presence of the protective layer of a low-molecular silver phase. Finally, the antibacterial activity of the BP/AgP nanocomposite was tested using selected bacteria biofilms. The grafted membrane showed clear inhibition properties by destruction and multiple damages of bacteria cells. The possible mechanisms of biocidal activity were discussed, and the investigation of the AgNP influence on the bacteria body was illustrated by AFM measurements. The results obtained concluded that the biopolymer membrane properties were significantly improved by the integration with ultra-small Ag nanoparticles, which added value to its applications as a biostatic membrane system for filtration and separation issues.     

Ionic Liquid-Mediated Biopolymer Extraction from Coffee Fruit

Ionic liquids (ILs) are effective solvents for biomass. Refined cellulose is commonly used; however, recent interest has grown to consider woody and herbaceous biomass and industrial crop residues like fruit peels. Here, the authors report results on the dissolution and shaping of cotton and coffee fruit (cascara) in 1,8-diazabicyclo[5.4.0]undec-7-inium acetate ([DBUH][OAc]). Cascara is a high-volume, low-value crop residue that poses an environmental and economic burden in producer countries leading to a high-value proposition if recoverable. Fruit/ionic liquid solutions (0–15% w/w dissolved at 60 °C) were characterized with respect to biomass concentration and shaped into fibers and films coagulated in DI water and methanol. Rheology was assessed using parallel plate rheometry. Cotton/IL mixtures formed better fibers compared to cascara-based solutions, which required 2.6× more biomass in solution for viable fiber formation. At 10% loading, fibers could be produced from untreated coffee fruit with diameters ranging from 18–100 microns. Coffee fruit residues and their precipitated films show that both cellulose and lignin dissolve in pure [DBUH][OAc]. Chemical characterization of cascara and cascara films demonstrates the conveyance of high concentrations of lignin and extracts that result in weaker mechanical properties. Further purification of cascara is required for effective use in structural applications.