纳米 TiO2包覆改性研究及其对 PVC 性能影响

利用硅烷偶联剂 KH–570对纳米 TiO2进行改性,探讨了改性工艺,通过正交试验得出改性的最佳工艺条件：分散液 pH=7.5,偶联剂加入量为7 mL,超声时间40 min,沉降实验和粒度分析结果表明,改性纳米 TiO2表面亲油性能显著提高,粒子间的团聚也得到改善。将改性及未改性纳米 TiO2加入 PVC 基体中,制得 PVC／纳米 TiO2复合材料,并对其进行紫外屏蔽性能测试和拉力测试。结果表明,添加改性纳米 TiO2的 PVC 复合材料紫外屏蔽性能和力学性能均显著高于添加未改性纳米 TiO2的材料,且当改性纳米 TiO2质量分数为3%时,PVC／改性纳米 TiO2材料的紫外屏蔽性能和力学性能最佳。     

酪素胶束结构及其纳米功能化的研究进展

总结了国内外关于酪素胶束微观结构及其胶束结构表征手段的研究,重点阐述了纳米粒子改性酪素胶束结构以获得功能材料的研究进展,希望对从事酪素研究的工作者有所帮助。     

Interfacial reactions of Sn–Zn–Ag–Cu alloy on soldered Al/Cu and Al/Al joints

This work shows the effect on the soldering process of the addition of Ag and Cu to Sn–Zn alloys. Soldering of Al/Cu and Al/Al joints was performed for a time of 3?min, at a temperature of 250°C, with the use of flux. Aging was carried out at 170°C for Al/Cu and Al/Al joints for 1 and 10 days. During the aging process, intermetallic layers grew at the interface of the Al/Cu joint at the Cu substrate. Intermetallic layers were not observed during wetting of Al/Al joints. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed. The experiment was designed to demonstrate the effect of Ag and Cu addition on the dissolution of Al substrate during the soldering and aging processes. In the solder alloys, small precipitates of AgZn₃ and Cu₅Zn₈ were observed.     

铜片在纳米碳化硼水基流体中的腐蚀行为

纳米流体已经被广泛地研究用于提高系统的传热性能和效率,然而对纳米流体的防腐蚀性能关注较少,因此本实验研究了铜片在纳米碳化硼(B4C)流体中的耐腐蚀性能。通过模拟加速防蚀实验,在不同分散情况下的纳米碳化硼流体中对铜片的腐蚀程度进行对比。实验结果表明:采用非离子分散剂,分散介质为膜处理水,流体呈中性或碱性且温度较低时,水基纳米碳化硼流体具有良好的抗腐蚀性能。     

Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong,Stable, and Tunable Surface Plasmon Resonances

Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field‐enhanced spectroscopies, plasmon‐mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well‐mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag‐coated Au NRs (AuNR@Ag) and Au‐coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface‐enhanced Raman spectroscopy that are some 30‐fold higher than that of AuNR@Au. When incubated with a H₂O₂ solution (0.5 m ), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.     

Intratumoral Thermal Reading During Photo‐Thermal Therapy by Multifunctional Fluorescent Nanoparticles

The tremendous development of nanotechnology is bringing us closer to the dream of clinical application of nanoparticles in photothermal therapies of tumors. This requires the use of specific nanoparticles that must be highly biocompatible, efficient light‐to‐heat converters and fluorescent markers. Temperature reading by the heating nanoparticles during therapy appears of paramount importance to keep at a minimum the collateral damage that could arise from undesirable excessive heating. In this work, this thermally controlled therapy is possible by using Nd³⁺ ion‐doped LaF₃ nanocrystals. Because of the particular optical features of Nd³⁺ ions at high doping concentrations, these nanoparticles are capable of in vivo photothermal heating, fluorescent tumor localization and intratumoral thermal sensing. The successful photothermal therapy experiments here presented highlight the importance of controlling therapy parameters based on intratumoral temperature measurements instead of on the traditionally used skin temperature measurements. In fact, significant differences between intratumoral and skin temperatures do exist and could lead to the appearance of excessive collateral damage. These results open a new avenue for the real application of nano­particle‐based photothermal therapy at clinical level.     

Locally Welded Silver Nano‐Network Transparent Electrodes with High Operational Stability by a Simple Alcohol‐Based Chemical Approach

As an indispensable aspect of emerging flexible optoelectronics, flexible transparent electrodes, especially those comprised of metal nanowires, have attracted great attentions recently. Welding the nanowire junctions is an effective strategy for reducing the sheet resistance and improving the operational stability of flexible nanowire electrode in practical applications. Herein, a simple alcohol‐based solution approach is proposed to weld crossed silver nanowires by chemically growing silver “solder” at the junctions of the nanowires, forming transparent silver nano‐network electrodes with improved electrical conductivity and operational stability. Remarkably, silver nano‐networks can be rapidly formed by this simple approach under ambient condition and room temperature, requiring no assistance from heat, light, electrical current, or mechanical pressure. Furthermore, our results show that the nano‐network electrode formed from large diameter nanowires offers a better operational stability, whose trend is opposite to that of the untreated electrodes. To demonstrate the potential application of the highly stable silver nano‐network from large diameter nanowires, organic solar cells fabricated on the nano‐network electrode incorporated with silicon dioxide nanoparticles achieve comparable performance to the ITO control device. Consequently, strategy demonstrated in this work can contribute to low‐cost and highly stable transparent electrodes in emerging flexible optoelectronics.     

Mn1-xZnxFe2O4 (0≤x≤1)纳米粉体的模板辅助溶胶凝胶法制备及其磁性能研究

通过模板辅助溶胶-凝胶法制备了一系列的Mn_1-xZn_xFe₂O₄(0≤x≤1,步长为0.2)纳米粉体。利用XRD和VSM对材料的物相和磁性能进行了表征,主要研究了Mn_1-xZn_xFe₂O₄分子式中Zn含量的变化对样品的微观结构和磁性能的影响。实验结果表明,具有不同Zn含量的Mn_1-xZn_xFe₂O₄样品均为尖晶石结构;随着Zn含量的增加,样品的晶面间距d、平均晶粒尺寸D、饱和磁化强度M_s和居里温度T_c都呈现出下降的趋势,而样品的矫顽力H_c则呈现出先升高后降低的趋势。分析认为,M_s的下降可以用Yafet-Kittel倾角理论解释,T_c的降低归因于晶格中反铁磁性耦合的降低,而H_c的变化则主要是由于材料的磁晶各向异性常数K₁的变化引起的。     

一种合成PS/Ag复合微球的简便方法

本文提出一种制备具有高金属覆载率及良好均匀性的PS/Ag复合微球的简便方法,可以避免PS微球的表面修饰。首先通过多元醇法制备具有良好单分散性的PVP覆盖的Ag纳米颗粒, 然后通过溶胀-异质凝聚法将这些Ag纳米颗粒负载于PS球上。对Ag纳米颗粒的尺寸分布及PS/Ag复合微球的表面形貌进行了研究,结果表明这种方法制得的PS/Ag复合微球具有良好的分散性与均一性,并且Ag颗粒的负载率可以通过Ag溶胶的加入量来调控。     

纳米ZnO和纳米MMT对低密度聚乙烯介电性能的影响

分别采用添加纳米ZnO和纳米蒙脱土(MMT)粒子的方法提高低密度聚乙烯(LDPE)的介电性能,选择偶联剂对纳米粒子进行表面修饰,并利用熔融共混法制备了纳米ZnO/LDPE和纳米MMT/LDPE复合材料,通过XRD、FTIR和DSC对试样进行表征。研究了复合材料的交流击穿特性,对试样进行了空间电荷试验。结果表明:通过偶联剂修饰,纳米粒子与聚合物之间的界面结合得到改善,且纳米粒子在基体中的分散性更好;同时复合材料的结晶速率提高,结晶结构更完善;添加纳米粒子可以不同程度地提高LDPE的击穿场强,当纳米ZnO和纳米MMT的质量分数均为3wt%时,复合材料的击穿场强达到最大,分别比纯LDPE的击穿场强高出11.0%和10.3%;纳米ZnO和纳米MMT都有抑制空间电荷的作用,且ZnO的抑制效果更明显。