磁性蛋白质微胶囊的声化学法构筑

通过声化学法制备了具有生物相容性的磁性蛋白质微胶囊, 利用高强度超声波辐照含有油酸改性磁性的Fe₃O₄纳米粒子的油相与蛋白质水溶液的两相界面, 只需几分钟即可得到磁性蛋白质微胶囊. 这种制备蛋白质微胶囊的方法快速简便, 高效环保, 可将分散于油相的疏水性药物直接装载, 不破坏药物. 在药物靶向传输等领域具有应用性.     

碳酸钙模板法制备高分子微球

模板法是一种制备粒径可控、形貌均一微球的有效途径。以球霰石形态存在的CaCO₃多孔微球具有生物相容、孔径均一,以及可在温和条件下分解等优点,适用于作为模板制备微球。本文在对CaCO₃模板进行简单介绍的基础上,从原料选取与应用角度综述了用CaCO₃模板法制备微球的研究进展。常用的装载CaCO₃多孔微球的方法有物理吸附、共沉淀和渗透法等,所用原料有天然高分子(如多糖、蛋白质、DNA)和合成高分子(如聚苯乙烯磺酸钠、聚乙烯醇)。利用CaCO₃模版制备的微球具有多孔洞或空心结构,尺寸形貌均一可控,特别适用于制药、药物递送、生物传感器及化学分析等领域。预计随着纳米技术的发展和生物医药领域的需求将推动CaCO₃模板法的研究,以期通过该方法制备出应用领域更加广泛的微球。     

Study on the toughening mechanism of PP/EVA dynamically crosslinked blend

The toughening mechanism of polypropylene (PP)/ethylene-co-vinyl acetate (EVA) dynamically crosslinked blend was investigated. The results indicated that dynamical crosslinking technology not only improved the interfacial adhesion between PP and EVA, but also increased the mechanical properties of PP/EVA blend. The quantitative and qualitative analysis of scanning electron microscopy (SEM) micrographs demonstrated that dynamical crosslinking technology could refine EVA particles in PP/EVA blend and promote the size distribution of EVA particles. The critical matrix ligament thickness of dynamically crosslinked and uncrosslinked blend was about 0.55 μm and 0.6 μm, respectively, indicating that the brittle-ductile transition occurred. Dynamic mechanical analysis (DMA) results illustrated that the tan δ peak of PP component in the dynamically crosslinked blend moved toward lower temperature compared with that of pure PP and the PP component in uncrosslinked blend; and the tan δ value of the dynamically crosslinked blend was higher than that of the uncrosslinked blend, which interpreted the toughening mechanism of dynamical crosslinking technology from the dynamic mechanical property of the blend.     

Microporous Polymeric 3D Scaffolds Templated by the Layer‐by‐Layer Self‐Assembly

Polymeric scaffolds serve as valuable supports for biological cells since they offer essential features for guiding cellular organization and tissue development. The main challenges for scaffold fabrication are i) to tune an internal structure and ii) to load bio‐molecules such as growth factors and control their local concentration and distribution. Here, a new approach for the design of hollow polymeric scaffolds using porous CaCO₃ particles (cores) as templates is presented. The cores packed into a microfluidic channel are coated with polymers employing the layer‐by‐layer (LbL) technique. Subsequent core elimination at mild conditions results in formation of the scaffold composed of interconnected hollow polymer microspheres. The size of the cores determines the feature dimensions and, as a consequence, governs cellular adhesion: for 3T3 fibroblasts an optimal microsphere size is 12 μm. By making use of the carrier properties of the porous CaCO₃ cores, the microspheres are loaded with BSA as a model protein. The scaffolds developed here may also be well suited for the localized release of bio‐molecules using external triggers such as IR‐light.

     

Fracture Micromechanisms of Polypropylene/Polycarbonate/Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (PP/ PC/SEBS) Ternary Blends: The Effects of SEBS Content

Ternary blends of polypropylene/polycarbonate/poly(styrene-b-(ethylene-co-butylene)-b-styrene) (PP/PC/SEBS) with varying SEBS contents were produced via melt blending in a co-rotating twin-screw extruder. The phase morphology of the resulting ternary blends and its relationship with bending and impact behaviors were studied. Transmission optical microscopy (TOM) of the crack tip damage zone and scanning electron microscopy (SEM) of impact fractured surfaces were performed to characterize the fracture mechanism. With increasing SEBS content in the PP/PC/SEBS ternary blends, the number of PC/SEBS core-shell particles increased and the size of the core-shell particles enlarged. It was shown that with an SEBS content of 5%, the crack initiation resistance decreased and then was almost unchanged with further increase of SEBS content, while resistance to crack growth increased continuously with increasing of SEBS content. Preliminary analysis of the micromechanical deformation suggested that the high impact toughness observed for samples containing 20 and 30 wt% of SEBS could be attributed to cavitation of the rubbery shell and, consequently, shear yielding of the matrix. This plastic deformation absorbed a tremendous amount of energy. Due to low interfacial adhesion between PC particles and PP matrix in samples containing 5 and 10 wt% of SEBS, debonding occurred too early, so the occurrence of matrix shear yielding was delayed and resulted in premature interfacial failure and, hence, rapid crack propagation.     

纳米孪晶界对可动位错演化特性与金属Al强化机理探究

位错是金属塑性变形普遍形式,对其可动位错演化特性与规律探寻并充分利用,将在金属强韧化提升中有着潜在基础前瞻性研究价值.本文基于分子动力学法对金属Al塑性变形的可动位错迁演特性展开研究,洞悉纳米压痕诱导的可动位错与孪晶界面间作用规律,揭示出金属强化微观机制,并分析单层孪晶界高度与多层孪晶界层间距对可动位错迁演、位错密度、硬度、黏着效应的影响.研究发现:高速变形下的金属非晶产生和密排六方结构的出现会协同主导Al基塑性变形,而孪晶界会阻碍可动位错滑移、诱导可动位错缠绕及交滑移产生,在金属承载提升中扮演了位错墙和诱导位错胞形成的微观作用.通过在孪晶界形成钉扎位错和限制位错迁移,在受限域形成高密度局域可动位错,显著强化了金属硬度和韧性,降低了卸载时黏附于探针表面的原子数.结果表明:Al基受载会诱导上表面局部非接触区原子失配斑出现;单层孪晶界高度离基底上表面距离减小时,位错缠绕和交滑移作用越明显,抗黏着效应也随之下降;载荷持续增加会诱驱孪晶界成为位错萌生处与发射源,并伴随塑性环的繁衍增殖.     

相变微胶囊改性UHMWPE复合材料的摩擦学性能

以石蜡为囊芯,蜜胺树脂为高分子囊壁材料,采用原位聚合法制备了相变微胶囊,并将其作为填料添加入超高分子量聚乙烯基体中,制得相变微胶囊改性UHMWPE复合材料.分析了该复合材料的硬度和物相组成,并研究了其在室温,低速和高速试验条件下的摩擦磨损性能.结果表明:微胶囊填料的加入可以起到较好的减摩降磨作用,填料的最适宜添加比例为20%,在低速试验条件下经改性的复合材料摩擦系数较纯UHMWPE降低60%以上,高速试验条件下改性后的复合材料耐磨性较之纯UHMWPE有明显提高,不同试验条件下材料呈现不同的磨损机理.     

Study on adsorption behavior of cesium using ammonium tungstophosphate (AWP)-calcium alginate microcapsules

A functional microcapsule was prepared by encapsulating the fine crystalline ammonium tungstophosphate(AWP) in calcium alginate polymer(CaALG).The characterization of AWP-CaALG microcapsule was examined by SEM and EPMA.The adsorption behavior of Cs(I),Rb(I),Sr(II),Pd(II),Ru(III),Rh(III),La(III),Ce(III),Dy(III) and Zr(IV) was investigated by the batch method.The batch experiments were carried out by varying the shaking times,HNO 3 concentration,and initial concentration of metal ions.Relatively large K d values above 10 5 cm 3 /g for Cs(I) were obtained in the range of 0.1-5 M HNO 3,resulting in a separation factor of Cs/Rb exceeding 10 2.In contrast,the K d values of Sr(II),Pd(II),Ru(III),La(III),Dy(III),Ce(III) and Zr(IV) were considerably lower than 50 cm 3 /g.The K d value of Cs(I) decreased in the order of the coexisting ions,H + > Na + >> NH 4 +,and a linear relationship with a slop of about 1 was obtained between log K d and log [NH 4 + ]([NH 4 + ] > 0.01 M).The adsorption of Cs(I) was found to be controlled by chemisorption mechanism,and followed a Langmuir-type adsorption equation.A high uptake percentage of 99.4% for Cs(I) was obtained by using the dissolved solutions of spent fuel from FBR-JOYO(JAEA).     

NUMERICAL STUDY ON PROPERTIES OF WEAK INTERLAYER OF LAMINATED COMPOSITE

<正>With assumption of material inhomogeneity on meso level,a three-point bending beam model has been adopted to simulate crack propagation in two dimensional laminated composite and to verify the toughening mechanism of energy dissipation and crack deflection along the weak interlayer.Moreover,the effect of strength,elastic modulus and thickness of the weak interlayer on both strength and toughness of the laminated composite have also been investigated in this paper.     

二苯基二甲氧基硅烷单体制备空心微胶囊的模板合成方法研究

制备了直径在700～1500 nm范围内的空心聚硅氧烷微球. 在O/W型聚二苯基硅氧烷微乳模板核上, 加入一定比例的二苯基二甲氧基硅烷(D型官能团)和甲基三甲氧基硅烷(T型官能团)的有机硅单体, 使之围绕在模板核表面聚合交联形成核壳结构的聚硅氧烷微胶囊, 利用合适溶剂溶解透析的方法去除模板核得到空心微胶囊. 通过TEM和AFM测定考察, 讨论了体系的各反应条件对空心微球的形态结构和大小分布的影响.