理论研究两亲性三嵌段共聚物在稀溶液中的微相结构

在此前本实验室工作的基础上借助采用实空间高分子自洽平均场理论在三维空间里研究了稀溶液中两亲性三嵌段共聚物的微相结构,模拟得到复杂形态的胶束结构,如球形胶束,棒状胶束,碗状胶束。通过改变分子作用参数的值依次观察到球状相,柱状相,碗状相。通过热力学分析表明,选择合适的分子作用参数,在稀溶液中不同胶束形态的形成强烈依赖于分子作用参数。通过模拟得到的结果可以发现不同形态相结构的形成对分子作用参数的变化的依赖。     

Modification of MnO(2) nanoparticles with rutin synthesized by Triton X-100 aggregations' template

Manganese dioxide (MnO(2)) nanoparticles have been prepared through the redox reaction between KMnO(4) and the nonionic surfactant Triton X-100 with the aid of rod-like micelles, hexagonal liquid crystals and reverse micelle templates, in which Triton X-100 acts both as template and reductant. MnO(2) nanorods (20-50?nm in diameter) can be obtained in rod-like micelles and hexagonal liquid crystals, whereas MnO(2) nanospheres (about 85 nm in diameter) are formed in reverse micelles. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to characterize the products. Modification of MnO(2) nanoparticles by rutin has been discussed using fluorescence spectra and UV-vis spectra, and the free radical eliminating investigations of surface-modified MnO(2) nanoparticles with rutin show that MnO(2) nanoparticles can improve the free-radical-scavenging activity of rutin.     

CTAB软模板法碳酸锶纳米棒制备

以六水氯化锶、氢氧化钠和尿素为原料,采用尿素水解均相沉淀法利用表面活性剂CTAB所形成的棒状胶束为软模板定向诱导制备出了晶形规整的碳酸锶纳米棒,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对其进行了表征。结果表明,碳酸锶纳米棒呈规则的直线状,长度在6μm以上,平均粒径约80nm,长径比达到70以上。对碳酸锶纳米棒的形成机理进行了初步的研究,最后进一步讨论了CTAB用量对粒子形貌的影响情况。     

Effect of supersaturation on the morphology of hydroxyapatite crystals deposited by electrochemical deposition on titanium

Cathodic deposition of calcium phosphate coating on titanium using electrochemical method was investigated in our study and well-defined hexagonal rod-like hydroxyapatite (HAp) crystals were synthesized. Scanning electron microscopic photographs of HAp coatings under different deposition durations revealed the morphology change of the HAp crystals in the coating film with the experimental process: from cone-like structure to hexagonal prism with sharp-angled tip, and finally turns to rod-like one with regular hexagonal cross section. It was suggested that both morphology and longitudinal length of the HAp crystals in the coating could be regulated by an accurate control of the degree of supersaturation of the aqueous system.     

棒状SiO_2-TiO_2核壳结构粒子的制备和表征

通过液相法制备棒状SiO2颗粒,研究正硅酸乙酯的浓度和聚乙烯吡咯烷酮的相对分子质量对棒状SiO2颗粒的影响,利用液相沉积法在最优化条件下制备的棒状SiO2颗粒表面均匀包覆TiO2,制备棒状SiO2-TiO2核壳结构粒子,并采用X射线衍射、透射电镜和傅里叶红外光谱等手段对棒状SiO2-TiO2核壳粒子进行表征。结果表明,随着聚乙烯吡咯烷酮相对分子质量的增大,SiO2颗粒由大头针状转变为棒状,随着正硅酸乙酯浓度的增大,棒状SiO2颗粒的长径比变大并出现类球状颗粒;棒状SiO2表面包覆的TiO2为针状,晶型为锐钛矿,包覆厚度为80 nm左右。     

APP对PUI泡沫泡孔结构及燃烧后炭层结构的影响

以聚磷酸铵(Ammonium Phosphate,APP)为阻燃剂,采用PI(poly-imide)预聚法制备了APP阻燃聚氨酯-酰亚胺泡沫塑料。利用偏光显微镜、扫描电子显微镜(SEM)、热重(TGA)观察分析了APP对泡沫泡孔结构、热稳定性和炭层形貌的影响。重点探讨了泡孔结构的变化对燃烧后的炭层形貌的影响,并模拟了炭层的形成过程。结果表明,随着APP添加量的增加,泡孔直径由540.39μm下降到277.83μm,泡沫密度增加;APP的加入使泡沫的残炭率增加了30%;泡孔的棱边和顶点分别炭化膨胀为炭层上的棒状炭层和球状炭层,而泡孔薄膜破裂成孔洞;并且随着APP添加量的增加,棒状炭层和球状炭层尺寸增加,孔洞变小。     

Mimicking the biomineralization of aragonite (calcium carbonate) using reverse-micelles under ambient conditions

Reverse micelles have been used, for the first time, to mimic the conditions suitable for the low-temperature (40 degrees C) synthesis of the high temperature and high pressure orthorhombic phase of calcium carbonate (aragonite) normally crystallizing in the sea as abalone shells and as natural pearls. The aragonite phase undergoes morphological changes under higher temperatures with long Y-junctions (at 40 degrees C) to shorter rod-like structures (at 85 degrees C). Pure calcite is obtained at higher reaction temperature. At a lower temperature (5 degrees C) homogeneous and monodisperse spheres of vaterite is obtained. The spherical particles after longer aging (168 h) aggregate to form nanorods and the self assembly is clearly seen at various stages by electron microscopic images.     

单硫键聚乳酸/聚乙二醇共聚物胶束的制备及超声响应行为

以二环己基碳二亚胺为脱水剂,4-二甲氨基吡啶为催化剂,合成了含有中心硫醚键聚乳酸/聚乙二醇嵌段共聚物(PEG-S-PLA)。动态光散射和扫描电子显微镜结果表明此嵌段共聚物能自组装形成纳米球形胶束,并且可在高强度聚焦超声刺激下导致自组装结构破坏,通过粒径和形貌变化证实了结构的破坏。进一步用紫外吸收光谱研究高强度聚焦超声控制释放行为,结果表明,此新型刺激响应胶束体系对疏水药物的控制释放具有重要意义。     

Controlled synthesis of manganese oxohydroxide (MnOOH) and Mn3O4 nanorods using novel reverse micelles

Novel reverse micelles of high CTAB concentration were successfully developed to synthesize MnOOH (manganese oxyhydroxide) nanorods with uniform diameters of about 10 nm and up to 200 nm in length under mild solution conditions and Mn3O4 nanorods with the same morphology could be obtained by calcining the precursors at 450 degrees C. The morphology and microstructure of the nanorods were investigated by transmission electron microscopy (TEM and HRTEM), XRD and TGA. The results showed that the concentration of CTAB was a key factor for the formation of MnOOH nanorods and only above 0.2 M the nanorods could be obtained. Moreover, the length of nanorods increased with the increase of CTAB concentration, while the diameter of nanorods retained steadily. In this way, the length of nanorods could be easily controlled from tens nanometers to hundreds nanometers by increasing the CTAB concentration from 0.35 M to 1.25 M. In addition, in our experiment the products were almost entirely rod-like shape, which indicated this method should be suitable for mass-producing.     

Zn基柱状ZnO取向生长机制

通过预氧化处理在Zn基底上制备了ZnO颗粒膜, 并由N₂H₄·H₂O-水热体系制备了Zn基柱状ZnO阵列。实验发现, 在Zn单一晶体学取向表面上柱状ZnO高度有序排列, 据此提出了Zn基柱状ZnO的自由生长取向机制。水热反应条件下, ZnO微晶通常具有沿c轴优先生长的结晶习性, 柱状体高度有序排列取决于ZnO晶核的状态。单一晶体学取向表面上晶核的状态一致, 决定了ZnO柱状体取向一致。Zn基柱状ZnO阵列光致发光谱分析表明, 在30~60 K之间, 近带边激子发射峰强度呈现反常温度依赖的“负热淬灭”现象, 该过程包含了两个无辐射过程和一个负热淬灭过程。     

双还原敏感的混合胶束用作为抗肿瘤药物的载体

通过酯化缩聚制备了含双硒键的聚合物聚乙二醇-缩-二硒二(十一酸)(PEG-SeSe-PEG),用核磁和红外确证了其结构。临界胶束浓度(CMC)结果表明,PEG-SeSe-PEG与两亲聚合物聚己内酯-二硫键-b-聚甲基丙烯酸二乙胺基乙酯/聚磺酸甜菜碱(PCL-SS-PDEA-PS)一样能够形成胶束,并且两者能形成混合胶束。用动态光散射和扫描电镜对胶束的粒径和还原敏感进行了研究。粒径变化显示混合胶束有双还原敏感性。用紫外分光光度计测定了胶束对疏水性抗癌药物模型姜黄素的载药量(DLC)和包封率(DLE)。PCL-SS-PDEA-PS占80%的双还原敏感胶束(混合胶束E)的载药量和包封率最高。体外释药结果显示,双还原敏感胶束在还原环境中的释药速率快于非还原环境。体外细胞毒性结果表明,双还原敏感胶束比PCL-SS-PDEA-PS胶束的细胞相容性好,而且载药E胶束能最好地抑制Hela细胞生长。     

不同共混方式下非对称嵌段共聚物PS-b-PMMA对PCHMA/PMMA体系增容效果的研究:界面与胶束的竞争

采用熔融共混方式,利用非对称两嵌段共聚物聚苯乙烯-b-聚甲基丙烯酸甲酯(PS-b-PMMA)对聚甲基丙烯酸环己酯(PCHMA)/聚甲基丙烯酸甲酯(PMMA)共混体系进行增容。重点研究了嵌段比、共混方式以及分散相PMMA分子量对共混体系中非对称嵌段共聚物分布的影响,即嵌段共聚物稳定相界面与所形成胶束数量、位置之间的竞争关系。结果表明,在低分子量PMMA情况下共混方式对非对称嵌段共聚物的分布影响显著,改变共混方式可以有效减少分散相中的胶束数量,使嵌段共聚物主要分布在二元不相容增容体系两相界面。另一方面,增大PMMA分子量会改变非对称嵌段共聚物在两相界面的界面曲率,导致其在分散相中的溶解性增大,在界面上的稳定性减小,从而迁移至分散相内部并最终形成胶束。     

Investigating the flow of rod-like particles in a horizontal rotating drum using DEM simulation

Understanding the flow and mixing of rod-like particles is fundamental because of the widespread use of rods in the process industry. In this paper, discrete element method is used to investigate the flow and mixing of rod-like particles in a horizontal rotating drum, with rod-like particles being modeled by super-ellipsoids. The influence of the aspect ratio of the rod and the rotation speed of the drum on the flow of rod-like particles is studied. The investigation of spherical particles is also included in this paper to reveal the differences between rod-like and spherical particles. The simulation results show that the flow of rods is more intermittent than that of spheres and that there is more intermittent flow for rod-like particles with larger aspect ratios. Both the aspect ratio of the rod and the rotation speed of the drum considerably influence particle mixing. The mixing rate, as quantified by the slope of the variation in the mixing index with respect to drum revolution, increases as rotation speed and aspect ratio decrease. The study of particle orientation indicates that rod-like particles have a preferred orientation during rotation of the drum: the major axis of the rod inclines to be parallel to the end plate of the drum.     

Preparation of hydroxyapatite rod-like crystals by protein precursor method

Hydroxyapatite (HAP) rod-like crystals were successfully prepared by thermolysis of bovine serum albumin (BSA)/calcium-phosphate (CaP) colloidal precursors. The precursors were obtained by precipitation method from Ca(H₂PO₄)₂ and Ca(OH)₂, in which BSA was added as regulation additive and ultrasound irradiation was utilized as assistant technology. The properties of the precursors, such as size distribution, morphology, thermodynamic changes, were determined by DLS, SPM and TGA-DTA. The characterization results from DLS, SPM, TG-DTA, XRD and SEM indicated that BSA interacted with CaP particles and formed about 7-130 nm BSA/CaP hybrid colloidal particles between 2 and 4 g/L of BSA concentration. With the increasing of sintering temperature, BSA disintegrated and burned out, and rod-like HAP crystals formed at about 600 °C. With the increasing of BSA concentration, the phase composition of products did not change and the HAP crystals became more uniform and smaller. The ratio of length to width ranged from 7.6 to 12 at 4 g/L BSA concentration. This method provides for a controllable bottom-up fabrication of HAP rod-like crystals.     

激光散射法研究氟油聚集态结构

本文用激光散射及偏光显微镜等技术剖析了几种氟油的聚集态结构。结果表明,全氟油为典型棒状晶聚集态结构,并有明显的温度依赖性,氟氯油也含少量棒状晶,也有温度依娘性;氟溴表现出无定型,具无规取向相关各向异性的特征。     

原位Al2O3片晶/Ce-TZP和SrO·6Al2O3棒晶/Ce-TZP复合材料的制备与显微结构

通过在Ce-TZP基体中加入AlOOH及矿化剂TiO₂或反应剂SrCO₃制备了原位Al₂O₃片晶/Ce-TZP复合材料和原位SrO·6Al₂O₃棒晶/Ce-TZP复合材料。在烧结过程中TiO₂促进Al₂O₃晶粒发生显著的各向异性生长原位生成的片晶、Al₂O₃与SrCO₃发生反应,原位生成的高度各向异性的棒晶,它们在基体中分布均匀,具有较大的纵横比。烧结温度对片晶/棒晶的大小和含量有明显影响。通过在基体中原位形成片晶或棒晶,材料的力学性能有明显的改善。     

原位生成棒晶增强Ti-B-C复相陶瓷的研究

Ｂ_４Ｃ与Ｔｉ在１８００°Ｃ×３５ＭＰa×１ｈ的烧结条件下反应生成了TiB₂ 棒晶,棒晶长度在１０～３０μｍ,其长径比在２～８范围．原位生成的棒晶赋予了材料具有极高的力学性能,材料的弯曲强度和断裂韧性分别为 ６８０ＭＰａ和 １２ＭＰａ·ｍ^１／２．通过 Ｘ射线衍射检测了材料的物相组成,利用扫描电镜及透射电镜观察了材料的显微结构．最后讨论了温度及金属Ｔｉ含量对棒晶ＴiＢ₂的生成及发育的影响．     

超重力场凝固对Cu-1.6%Cr共晶合金组织的影响

本实验分别在普通重力场和4230g超重力场下制备了Cu_(98.4)Cr_(1.6)合金的凝固样品,研究了重力场对Cu_(98.4)Cr_(1.6)合金棒状共晶尺寸和宏观偏析情况的影响。结果表明:与普通重力场的凝固组织相比,当Cu_(98.4)Cr_(1.6)合金棒状共晶在4230g超重力场下凝固时,棒状共晶组织得到了明显的细化,其直径由250~350nm降至100~200nm。同时,Cu_(98.4)Cr_(1.6)共晶合金沿超重力场方向的硬度和成分分布基本一致,未出现明显的宏观偏析。     

Synthesis of flower- and rod-like nickel sulfide nanostructures by an organic-free hydrothermal process

Well-crystalline flower- and rod-like NiS nanostructures have been synthesized by an organic-free hydrothermal process at a low temperature of 200 °C. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were employed to characterize the as-synthesized NiS nanostructures. The effects of temperature and reaction time on the morphology have been also investigated. The two-step flake-cracking mechanism for the formation of flower- and rod-like NiS nanostructures was discussed. The products were also investigated by photoluminescence (PL) spectroscopy.     

Physical stability and lyophilization of poly(epsilon-caprolactone)-b-poly(ethyleneglycol)-b-poly(epsilon-caprolactone) micelles

The stability and lyophilization of core-shell PCL-PEG-PCL micelles were investigated by fluorescence spectra, DLS, DSC, WAXD, and FT-IR. The prepared micelles were not stable when they were stored in aqueous dispersion under different condition. Their size increased in the first 20 days and decreased gradually when the storage period was extended. Lyophilization experiment showed that the cryoprotective agent (glucose) was an essential additive to protect the micelles from aggregating during the lyophilization process. After lyophilizing and re-dispersion, the PCL-PEG-PCL micelles became larger in size compared to as-prepared ones. DSC, WAXD, and IR measurements indicated the hydrogen bonding was formed between the hydroxyl group in glucose and the carbonyl group in PCL-PEG-PCL micelles. The effect of added glucose on protection of micelles from aggregation can be explained by the formation of hydrogen bonding with PCL-PEG-PCL micelles and the formation of solid glucose matrix.