Atom transfer radical polymerization (ATRP): A versatile and forceful tool for functional membranes

The progress in atom transfer radical polymerization (ATRP) provides an effective means for the design and preparation of functional membranes. Polymeric membranes with different macromolecular architectures applied in fuel cells, including block and graft copolymers are conveniently prepared via ATRP. Moreover, ATRP has also been widely used to introduce functionality onto the membrane surface to enhance its use in specific applications, such as antifouling, stimuli-responsive, adsorption function and pervaporation. In this review, the recent design and synthesis of advanced functional membranes via the ATRP technique are discussed in detail and their especial advantages are highlighted by selected examples extract the principles for preparation or modification of membranes using the ATRP methodology.     

LPCVD制备二氧化硅薄膜工艺研究

采用TEOS源LPCVD法制备了SiO2薄膜,采用膜厚仪对薄膜的厚度进行测试.通过不同条件下SiO2薄膜的厚度变化,讨论了TEOS源温度、反应压力及反应温度等工艺条件对淀积速率和均匀性的影响.结果表明,在40℃,50 Pa左右,淀积速率随TEOS源温度、反应压力基本呈线性增大.通过多次试验改进,提出了SiO2膜淀积的典...     

TEOS LPCVD技术在SiC功率器件工艺中的应用

应用正硅酸乙酯(TEOS)LPCVD技术实现二氧化硅在SiC晶片表面的淀积,在一定程度上弥补了SiC氧化层过薄和PECVD二氧化硅层过于疏松的弊端。采用TEOS LPCVD技术与高温氧化技术的合理运用,既保证了氧化层介质的致密性和与SiC晶片的粘附能力,又提高了器件的电性能和成品率,同时避免了为获得一定厚度氧化层长时间高温氧化的不足。采用此技术后,SiC芯片的直流成品率得到提高,微波功率器件的对比流片结果显示微波性能也得到了明显的提升,功率增益比原工艺提高了1.5 dB左右,功率附加效率提升了近10%。     

氟硅改性丙烯酸酯有机/无机杂化无皂乳液制备及性能表征

以正硅酸乙酯（TEOS）为水解前驱体制得二氧化硅（SiO2）,并通过硅烷偶联剂（KH570）表面改性后,与全氟烷基乙基丙烯酸酯（FM））等乙烯基单体聚合,通过无皂乳液聚合方法制备了氟硅改性丙烯酸酯有机/无机杂化无皂乳液。FT-IR分析表明,TEOS水解为SiO2,并与丙烯酸酯单体、氟单体参与了共聚反应;采用TEM及AFM对乳胶粒的形态结构进行表征,发现乳胶粒分布较为均一,平均粗糙度和致密程度较高;DLS分析表明乳液平均粒径为49.49nm;接触角测试表明氟单体、硅溶胶及KH570的加入显著提高了涂膜的防水性。     

Electrospinning of poly(dimethyl siloxane) by sol–gel method

Crosslinked poly(dimethyl siloxane) (PDMS) fibers were fabricated by electrospinning in combination with a sol–gel process followed by heat treatment. Before and after heat treatment, the changes in the chemical and thermal properties of the electrospun PDMS fibers were examined by differential scanning calorimetry (DSC), equilibrium swelling tests, and contact angle measurements. There was no significant change in morphology and average diameter of the as‐spun PDMS fibers after heat treatment. The tensile properties of the as‐spun PDMS fibers mat increased with increasing heat treatment temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of Nd:YAG transparent ceramics with both TEOS and MgO additives

Neodymium doped YAG transparent ceramics were fabricated by vacuum reactive sintering method using commercial α-Al₂O₃, Y₂O₃ and Nd₂O₃ powders as the starting materials with both tetraethyl orthosilicate (TEOS) and MgO as sintering aids. The morphologies and microstructure of the powders and Nd:YAG transparent ceramics were investigated. Fully dense Nd:YAG ceramics with average grain size of ∼10 μm were obtained by vacuum sintering at 1780 °C for 8 h. No pores and grain-boundary phases were observed. The in-line transmittance of the ceramic was 83.8% at 1064 nm.     

立方氮化硼表面Stober法包覆硅氧纳米涂层及其表征

在立方氮化硼聚晶复合材料制备中,为改善晶体相的偏聚,其思路之一便是将晶体相与粘接相预先制备成带有核-壳结构的原料。先采用Pirnaha溶液对cBN进行羟基化改性,改善其亲水性,使其容易分散并带有电荷的基础上,再用Stober法进行硅氧包覆处理,在氨水和少量水的作用下,以乙醇作为分散剂,用TEOS硅氧烷为原料,在室温条件下反应,利用水解-凝胶法让硅醇以非自发形核的方式在c BN粉体表面聚合,并对试验结果进行TEM,SEM,EDS,XRD,FTIR表征。结果表明,通过对立方氮化硼粉体进行硅氧纳米涂层包核处理,成功得到了立方氮化硼-氧化硅微/纳米核壳结构,包核形貌良好,包覆层厚度可由TEOS加入量的不同而调节。对无机材料核壳结构制备和立方氮化硼与结合剂的均布有实际意义。     

纤维载体对有机硅溶胶-凝胶涂层的影响

以纤维素织物和合成纤维织物为载体,以硅酸乙酯（TEOS）为水解前驱体,对织物载体进行溶胶-凝胶涂层整理。测定硅凝胶在织物载体上的固载量,研究纤维载体化学结构、形貌及拒水整理对有机硅溶胶-凝胶涂层的影响。利用X射线光电子能谱（XPS）分析整理前后元素成分变化及结合状态;利用Brunauer–Emmet–Teller（BET）比表面积、傅里叶红外全反射（FTIR-ATR）和X射线衍射（XRD）分析溶胶-凝胶整理前后纤维表面形貌和化学成分的变化。结果表明：纤维成分和形貌影响凝胶在织物上的固载量,有机硅凝胶主要通过偶极作用和氢键作用在织物表面形成涂层;拒水整理对硅凝胶的固载量有显著的影响。     

Organic–Inorganic Hybrid Films Based on Hydroxylated Soybean Oils

Hybrid organic–inorganic films were prepared using four different hydroxylated soybean oils (HSO) or epoxidized soybean oil as organic precursor and tetraethyl orthosilicate (TEOS) as inorganic precursor in a mass ratio of HSO:TEOS of 90:10. The films were macroscopically homogeneous and were characterized by swelling and extraction in solvent, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) including energy dispersive spectroscopy (EDX), adhesion and hardness. Their properties varied as a function of the number of OH groups present in the HSO. The best hybrid system was HSOF198/TEOS, with an OH value of 198 mg of KOH/g, which presents lower swelling coefficient, very good adhesion on aluminium surface and good hardness.     

Acid-catalyzed moisture-curing polyurea/polysiloxane ceramer coatings

The para-toluene sulfonic acid (p-TSA) was used to catalyze the moisture curing of an organic/inorganic hybrid coating system. The organic phase was based on the isocyanurate of 1,6-hexamethylene of diisocyanate (HDI). The inorganic phase was based on the prepolymerized oligomers of tetraethyl orthosilicate (TEOS). An alkoxysilane-functionalized HDI isocyanate was added into the coating formulation to aid in phase miscibility. The general coating and tensile properties were evaluated as a function of the acid catalyst concentration. In addition, the films were analyzed using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The results indicated that the acid catalyst enhanced the adhesive properties of the hybrid coatings. The addition of the acid catalyst increased the changed crosslink density of films and decreased the crystallinity of the organic phase.