二氧化硅表面修饰硅烷偶联剂APTS的过程和机制

二氧化硅表面经过硅烷偶联剂γ-氨丙基三乙氧基硅烷(APTS)修饰后,在橡胶、塑料、催化剂、色谱柱、吸附剂、生物和医药等领域中具有独特的应用性能,大量文献结合特定应用体系研究二氧化硅表面修饰APTS的基本规律,以实现理想可控的修饰效果。总结这些分散性研究结果,有利于在新的基础上有效地促进研究的深入。在分析文献的基础上,系统地阐述了二氧化硅表面修饰APTS的反应机理、修饰工艺、反应动力学、修饰层稳定性和结构形貌等方面的研究进展,提出了目前研究还存在的问题和进一步的研究方向。     

纳米二氧化硅微球表面接枝嵌段聚合物的制备及其在丙烯酸结构胶体系中的性能研究

以二氧化硅微球为模板,将其表面修饰上活性官能团。通过表面引发可控/“活性”自由基聚合,连续引发苯乙烯和甲基丙烯酸2-羟基乙酯聚合,得到表面接枝嵌段聚合物的纳米二氧化硅微球,并对其进行表征。将表面修饰的二氧化硅微球用于丙烯酸结构胶体系,并和未修饰二氧化硅微球的体系进行对比。研究结果表明：通过结构表征证明了目标产物合成成功;将表面修饰的二氧化硅微球用于丙烯酸结构胶体系,聚合物改性的纳米二氧化硅在拉伸强度、断裂伸长率和剪切强度等性能的表现均优于未改性的纳米二氧化硅;纳米二氧化硅在固化体系中具有增强增韧的作用,表面接枝聚合物改性后,其性能表现更优。     

玻碳电极表面修饰的应用研究进展

裸玻碳电极的性质、功能较为单一,应用较为有限。为了拓展其应用领域,对玻碳电极进行表面修饰,玻碳电极表面修饰已经成为当前电化学研究的一个热点。文章在研究玻碳电极表面修饰相关文献的基础上,主要对当前玻碳电极表面修饰的应用领域及表面修饰剂的种类进行简要综述,以期为该领域的深入研究提供参考。     

单分散纳米二氧化硅微球表面化学修饰与表征

通过溶胶-凝胶法制备纳米二氧化硅微球,以乙醇作为分散介质,用硅烷偶联剂采用一步法对纳米二氧化硅进行了表面化学修饰。通过X-射线光电子能谱（XPS）、透射电子显微镜（TEM）和傅立叶红外光谱仪（FT-IR）等手段对其改性前后效果进行了分析。研究发现修饰后的纳米二氧化硅微球的疏水性增强;硅烷偶联剂与纳米二氧化硅表面羟基发生了化学反应。     

介孔二氧化硅载体在酶蛋白固定化中的应用

介孔二氧化硅材料因制备简单、生物相容性良好、比表面积和孔径可控、表面修饰基团多样等特点,被广泛应用于酶蛋白的固定化。主要综述了介孔二氧化硅对水解酶、氧化还原酶等酶蛋白的固定化效果及其影响固定化效果的因素,展望了介孔二氧化硅在酶蛋白固定化中的应用前景及存在的挑战,为介孔二氧化硅更好地应用于固定化酶制剂的制备奠定基础。     

钛修饰纳米二氧化硅交联剂及胍胶压裂液研究

γ-氨丙基三甲氧基硅烷与硅酸钠水解制得表面修饰纳米二氧化硅,四氯化钛与表面修饰纳米二氧化硅反应,制得钛修饰纳米二氧化硅交联剂,粒径主要分布在6～11 nm之间,可有效降低羟丙基胍胶用量及残渣含量。配制了纳米二氧化硅交联剂交联的羟丙基胍胶压裂液,羟丙基胍胶浓度为0.35%～0.4%。室内研究表明,该压裂液体系各项性能良好,在170 s^(-1),150℃下,剪切120 min,粘度102 mPa·s; 120℃下破胶60 min,破胶液粘度2.32 mPa·s;表面张力23.53 mN/m,界面张力0.91 mN/m;防膨率88.56%;残渣含量227 mg/L;岩心基质渗透率损害率为9.63%～15.77%,压裂液耐剪切性能、破胶性能、助排性能、储层保护性能等各项性能良好,满足压裂要求。     

二氧化硅负载梳状聚醚三相催化剂的合成及其催化性能研究

以表面经偶联剂修饰的二氧化硅为载体,通过聚(β-氯乙基缩水甘油醚)和醇钠反应,合成了两种梳状聚醚三相转移催化剂,研究了它们在碘代、二氯卡宾对双键加成和混合醚制备反应中的催化活性.结果表明,这类催化剂具有良好的催化活性和重复使用性能.     

改性纳米二氧化硅的制备及其在溶聚丁苯橡胶/顺丁橡胶并用胶中的应用

用偶联剂KH570作修饰剂,采用液相原位表面修饰技术制备改性纳米二氧化硅,并考察其在溶聚丁苯橡胶(SSBR)/顺丁橡胶(BR)并用胶中的应用。结果表明:与未改性纳米二氧化硅相比,改性纳米二氧化硅在橡胶基体中的分散性较好,与橡胶的相容性提高,团聚减弱;改性纳米二氧化硅/SSBR/BR复合材料的物理性能和耐磨性能提高,Payne效应减弱;修饰量为50 mmol·kg~(-1)的改性纳米二氧化硅/SSBR/BR复合材料物理性能、耐热老化性能和耐磨性能最好。     

改性纳米二氧化硅的制备及其在溶聚丁苯橡胶/顺丁橡胶并用胶中的应用

摘要：以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)为修饰剂,采用液相原位表面修饰技术,制备了可分散性纳米二氧化硅,并将这种改性后的纳米二氧化硅应用到溶聚丁苯橡胶/顺丁橡胶体系,对其进行力学性能、磨耗性能、流变性能测试,考察了修饰剂的不同用量对复合材料上述性能的影响。傅里叶红外光谱表明,KH570已经成功通过化学键键合在二氧化硅表面,扫描电镜显示其团聚减弱,分散性提高。橡胶纳米复合材料的力学性能有所改善,在修饰量为25-50mmol/kg时性能最佳;耐磨性能明显提高,尤其是修饰量为50mmol/kg时,磨耗体积最少,降低了33.85%;明显降低了Payne效应,减弱了二氧化硅的团聚,提高了其在橡胶基体中的分散性。     

基于无机材料包埋磁性纳米复合颗粒的制备研究

磁性纳米颗粒由于具有一些奇异的物理特征而被广泛的应用于各个领域。因此,有关其表面修饰及复合颗粒的制备已成为目前的一个研究热点。考虑到绝大部分综述性文献都集中在高分子材料的包埋与修饰上,而有关无机材料的包埋则较少涉及。以二氧化硅、碳、金等材料为例着重介绍了基于以上无机材料包埋磁性纳米复合颗粒在近几a来的研究进展,并对其发展前景进行了展望。     

Silica-Pillared Clay Derivatives Using Aminopropyltriethoxysilane

Silica pillared montmorillonite has been synthesized using aminopropyltriethoxysilane (APTS), the organic part of which is removed upon calcination. A good intercalation has been established as determined by X-ray diffraction, thermogravimetric analysis and fourier-transform infrared measurements. The concentration of the APTS solution has an influence on the density of the pillars in the interlayer space. In case of enhanced APTS concentration, a material with lower surface area and pore volume is obtained, due to the clay interlayer space being completely occupied by silica pillars. Therefore a templated synthesis method is applied in order to reduce the density of the pillars between the clay sheets. By a pre-intercalation of the clay with cetyltrimethylammonium ions prior to the modification with APTS, the clay sheets are driven apart allowing a more easy intercalation of the APTS molecules. Analysis results show an increase in interlayer free spacing (IFS) to a value of 7.4 Å probably due to the insertion of two layers of silica (—Si—O—Si—) between the clay sheets. A maximal surface area of 252 m²/g and a micropore volume of 0.072 cc/g can be obtained in case of the templated synthesis method.     

The influence of temperature and interface strength on the microstructure and performance of sol–gel silica–epoxy nanocomposites

A series of silica–epoxy nanocomposites were prepared by hydrolysis of tetraethoxysilane within the organic matrix at different processing temperatures, i.e., 25 and 60 °C. Epoxy matrices reinforced with 2.0–10.0 wt% silica were subsequently crosslinked with an aliphatic diamine hardener to give optically transparent nanocomposite films. Interphase connections between silica networks and organic matrix were established by in situ functionalization of silica with 2.0 wt% γ-aminopropyltriethoxysilane (APTS). The microstructure of silica–epoxy nanocomposites as studied by transmission electron microscopy indicated the formation of very well-matched nanocomposites with homogeneous distribution of silica at relatively higher temperatures and in the presence of APTS. Thermogravimetric and static mechanical analyses confirmed considerable increase in thermal stability, stiffness, and toughness of the modified composite materials as compared to neat epoxy polymer and unmodified silica–epoxy nanocomposites. A slight improvement in the glass transition temperatures was also recorded by differential scanning calorimetry measurements. High temperature of hydrolysis during the in situ sol–gel process not only improved reaction kinetics but also promoted mutual solubility of the two phases, and consequently enhanced the interface strength. In addition, APTS influenced the size and distribution of the inorganic domain and resulted in better performance of the modified silica–epoxy nanocomposites.     

Properties of epoxy molding compound according to the pretreatment method of an amino‐silane coupling agent on epoxy or phenol resin

An amino‐functional silane coupling agent, which is an important component for epoxy molding compound (EMC), has been used by diverse methods, such as integral addition into a mixed powder and pretreatment on silica or on resin. However, the homogeneous dispersion of the amino‐functional silane coupling agent in mixed powder is limited with integral addition, and the possibility of white gel formation, sometimes causing gate blocking during the transfer‐molding process, due to the aggregation of silica with the coupling agent cannot be completely removed by it. The pretreatment of the amino‐functional silane coupling agent on silica has been adopted as an alternative process, but the process is expensive and limited in mass production. Although the pretreatment of the coupling agent on resin as another method has also been used by some EMC manufacturing companies, it has hardly been known in which resin phase, the epoxy or hardener, the silane coupling agent should be pretreated for better mechanical properties of EMC. In this study, the pretreatment of the amino‐functional silane coupling agent on epoxy or phenol resin, essential components of EMC, has been investigated with respect to the reaction during the pretreatment and the properties of EMC according to the different pretreatment methods. In the case of the pretreatment on epoxy, the amino‐functional silane coupling agent rapidly forms an adduct with epoxy via a ring‐opening reaction, whereas its alkoxy groups are well preserved. The glass‐transition temperature and flexural strength of the EMC by the application of the pretreatment method on epoxy are lower than those by the pretreatment on phenol. It is thought that the degree of linkage between the resin matrix and silica becomes lower because of the confinement of aminopropyltriethoxy silane (APTS) within the epoxy matrix through an irreversible reaction with epoxy in advance. In the case of the pretreatment on phenol, most of the alkoxy groups in the coupling agent are assumed to be replaced with protonic nucleophiles such as phenol, generating an equivalent amount of alcohol. Because the adduct between the phenol and amino‐functional silane coupling agent can be easily regenerated during the manufacturing process, it is thought that the pretreatment method of APTS on phenol helps APTS disperse well within EMC. Actually, the glass‐transition temperature and flexural strength of EMC by the application of the pretreatment method on phenol are higher than those by the integral addition method and the pretreatment on epoxy. However, they become lower as the degree of reaction of silane with phenol increases. The pretreatment of the amino‐functional silane coupling agent on phenol shows lots of advantages over the previous methods. From the viewpoint of the process, the homogeneous dispersion of the coupling agent can be obtained with consistency, and the possibility of white gel formation can also be completely removed by it. From the perspective of properties, through a controlled pretreatment on phenol resin, better mechanical properties of EMC can be obtained than those through the pretreatment on epoxy. In addition, the pretreatment process on phenol is simple and feasible for mass production. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2171–2179, 2006     

纳米二氧化硅的表面改性及其应用进展

综述了国内外纳米二氧化硅的表面改性方法，并分类介绍了粉体纳米二氧化硅和胶体纳米二氧化硅的表面改性方法及其对材料性能的影响，分析讨论了纳米二氧化硅与有机聚合物的反应机理及其在聚合物基复合材料中的应用，展望了其发展前景。     

超细白炭黑的表面改性研究

在反应器中,以乙醇为分散剂,以六甲基二硅胺烷为改性剂,自制超细白炭黑为原料,初步确定了超细白炭黑表面改性的最优工艺条件为:反应温度85℃,改性剂用量2%,反应时间100min,预处理温度200℃,预处理时间2 h。改性白炭黑XRD分析显示,其表面改性并不会改变白炭黑的无定形态,SEM分析可知改性后的白炭黑具有很好的分散性。     

Effect of surfactant concentration on the stacking modes of organo-silylated layered double hydroxides

The effects of the surfactant concentration on the structure, morphology and thermal property of silylated hydrotalcites have been investigated. By in-situ coprecipitation, the surfaces of layered double hydroxides (LDHs) have been modified by using 3-aminopropyltriethoxysilane (APTS) and anionic surfactant, Na-dodecylsulfate (SDS). Two different stacking modes in the resultant materials were detected by X-ray diffraction (XRD). One has an identical structure of LDHs, in which the SDS and APTS only bond to the outside surfaces and plate edges of LDH. The other is with enlarged interlayer distance, in which SDS and APTS combined with the inside surfaces of LDH. With the increased loading of SDS and APTS, the surface of the modified LDH appeared rough as observed in the transmission electron microscopy (TEM) images. The attenuated total reflection Fourier-transform infrared (ATR FTIR) spectra of the silylated hydrotalcites showed a series of bands attributed to –NH₂ and Si–O–M (M = Mg and Al), proving that APTS has successfully been grafted onto LDH. The thermogravimetric curves (TG) showed that the silane grafted samples have less –OH concentration and less interlayer water, as a result of the –OH consumption during the condensation reaction between Si–OH and –OH on LDH surface. These nanomaterials are of potential applications including clay-based nanocomposites, adsorbents for removal of organic contaminants from water and flame retardant materials.     

Preparation and Properties of Nanocomposites Derived from Aromatic Polyamide and Surface Functionalized Nanoclay

Nanocomposites were synthesized from polyamide and aminosilane functionalized montmorillonite through solution intercalation method. Polyamide resin was prepared by reacting a mixture of p-phenylenediamine and 4,4′-oxydianiline with isophthaloyl chloride (IPC) in N,N′-dimethyl acetamide (DMAc) under anhydrous conditions. The resulting chains were end capped with carbonyl chloride using slight excess of IPC near the end of reaction. 3-Aminopropyltriethoxysilane (APTS) was used for the surface modification of clay. Triethoxysilane groups of APTS promoted the reaction between silane and hydroxyl groups on the surface of clay. The compatibility between the two disparate phases was achieved through interaction of free amine groups of modified clay with carbonyl chloride of the matrix. Thin films obtained by evaporating the solvent were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), and tensile measurements. XRD and TEM results revealed the formation of partially delaminated and intercalated clay platelets in the matrix. Mechanical data showed improvement in the tensile strength and moduli of the nanocomposites with clay loading up to 6 wt.%. The glass transition temperature increased up to 134°C for the nanocomposites containing 6 wt.% clay content and also the thermal stability augmented with increasing clay loading.     

Effect of different surface treatments on polypropylene composites reinforced with yerba mate fibers: Physical,mechanical, chemical,and morphological properties

This study presents the preparation of post-consumer polypropylene (r-PP) composites filled with 30 wt% yerba mate (YM) stick particles. To improve the fiber–matrix adhesion, three surface treatments were performed: alkaline treatment with sodium hydroxide (NaOH) and use of 3-aminopropyltriethoxysilane (APTS) and maleic anhydride graft polypropylene copolymer (PP-g-MA) as coupling agents. Mechanical properties including tensile, flexural, and impact resistance were determined, and chemical (Fourier transform infrared spectroscopy [FTIR]), physical (water absorption), and morphological analyses were performed. The main findings show that the treatments were efficient in improving the mechanical properties of the composites, with emphasis on the r-PP/YM30/APTS and r-PP/YM30/PP-g-MA composites, which proved to be superior in tensile, flexion and impact strength and absorption of water compared to the untreated composite. The morphological analysis showed a better interaction between the fiber and the polymeric matrix for the composites with YM/APTS and YM/PP-g-MA, which corroborates the results of tensile and flexural strength, as well as with the spectra of FTIR in which the chemical modification of the fibers is observed. However, the results show that these treatments are promising in obtaining composites with recycled matrix with better properties.     

Study of the Preparation of Flavone Imprinted Silica Microspheres and Their Molecular Recognition Function

The aim of this study is to prepare flavone imprinted silica with good sphericity. Previous studies have demonstrated that imprinted silica can be synthesized using a simple sol‐gel method and a grinding‐sieving process. Despite the simplicity of the synthetic method, the appearance of the final product obtained is often very irregular and nonuniform. This product has many utilization issues and problems, e.g., residues and low operability. In this study, one type of novel spherical flavone imprinted silica was synthesized. A sol‐gel method and molecular imprinting technique were employed. By using luteolin as a template molecule, aminopropyltriethoxysilane (APTS) as the functional monomer, tetraethoxysilane (TEOS) as the cross‐linking agent, molecularly imprinted silica microspheres were prepared via a two‐stage reaction. The preparation conditions were monitored by the appearance of the products. SEM images show that under optimum conditions, the diameters of these microspheres are ca. 20–30 μm. The amino group adsorption peaks can be seen from the IR spectra. Results from elemental analysis indicate that 3.206 μmol of amino groups were successfully introduced into 1 g of product. This microspheric adsorbent has a high adsorption capacity to the template molecule, high adsorption selectivity and reproducibility. The adsorption capacity amounted to 32.987 mg/g and the separation factor was up to 84.3, while the adsorption capacity hardly decreased after 15 cycles.