含异质元素聚碳硅烷的制备及应用研究进展

回顾了聚碳硅烷陶瓷先驱体的制备方法及其化学结构,着重对近年来几种含异质金属元素聚碳硅烷先驱体的制备、化学结构及应用的研究进展进行了综述,并提出了今后的发展方向。     

超支化有机硅树脂的制备、改性及其应用

综述了以ABn(n=2,3,4)型单体制备超支化聚碳硅烷、超支化聚碳硅氧烷和超支化聚烷氧基硅烷三类超支化有机硅树脂的合成工艺及其改性技术,重点介绍了制备含不饱和双键和环氧基团的功能性超支化有机硅树脂单体的分子设计与制备技术。论述了超支化有机硅树脂在薄膜材料、复合催化剂、增强助剂等领域的应用研究进展。     

聚铁碳硅烷先驱体的合成工艺研究

本文研究了聚铁碳硅烷的合成,探索了裂解温度、反应温度、二茂铁等因素对合成聚铁碳硅烷(PFCS)工艺的影响;元素分析、红外光谱、氢谱分析表明:铁被引入到聚铁碳硅烷(PFCS)中,PFCS与聚碳硅烷(PCS)的结构相似。     

含硼聚碳硅烷的制备及热解行为EI北大核心CSCD

为制备陶瓷产率高、高温性能优良的碳化硅(SiC)陶瓷先驱体,利用频那醇硼烷(PINB)与聚碳硅烷(PCS)的脱氢偶合反应,对聚碳硅烷进行化学改性。改变PINB与PCS的质量比(1∶20、1∶10、1∶5),制备了一系列不同硼(B)含量的含硼聚碳硅烷(PBCS)。通过傅里叶变换红外光谱分析、核磁共振氢谱分析、热重分析以及X射线衍射分析等手段研究了PBCS的组成、结构及热解行为。结果表明,通过B-H键的反应将B元素以PINB骨架形式引入PCS结构;引入B元素可以将PCS的陶瓷产率从78%提高至92%;另外,B元素的引入引起PCS的交联,PBCS的热解过程分3个阶段。同时B元素的引入抑制了SiC晶体的生长,将材料的耐温性能提高至1400℃。     

KH-560改性液体聚硫橡胶的制备与表征

采用γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH-560)对液体聚硫橡胶进行封端改性,制备出一种新型端烷氧基硅烷改性聚硫橡胶。用化学滴定法测定了反应中巯基的转换率,用傅里叶变换红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)对改性聚硫橡胶的结构进行了分析,用凝胶渗透色谱(GPC)测定了改性聚硫橡胶的分子质量。研究结果表明,KH-560的环氧基与液体聚硫橡胶的巯基发生了反应,通过调节反应物的比例可以控制巯基的转换率,改性聚硫橡胶的数均相对分子质量(Mn)为3641,多分散系数(PDI)为1.578,改性聚硫橡胶可以作为单组分弹性聚硫密封胶的基胶。     

含硼聚碳硅烷的制备及热解行为

为制备陶瓷产率高、高温性能优良的碳化硅(SiC)陶瓷先驱体,利用频那醇硼烷(PINB)与聚碳硅烷(PCS)的脱氢偶合反应,对聚碳硅烷进行化学改性。改变PINB与PCS的质量比(1∶20、1∶10、1∶5),制备了一系列不同硼(B)含量的含硼聚碳硅烷(PBCS)。通过傅里叶变换红外光谱分析、核磁共振氢谱分析、热重分析以及X射线衍射分析等手段研究了PBCS的组成、结构及热解行为。结果表明,通过B-H键的反应将B元素以PINB骨架形式引入PCS结构;引入B元素可以将PCS的陶瓷产率从78%提高至92%;另外,B元素的引入引起PCS的交联,PBCS的热解过程分3个阶段。同时B元素的引入抑制了SiC晶体的生长,将材料的耐温性能提高至1400℃。     

含钛聚碳硅烷的合成、表征及其形成机理研究

以合成聚碳硅烷的副产品——液态小分子聚碳硅烷（LPCS）和钛酸正丁酯为原料,合成含钛聚碳硅烷,并通过产物的凝胶液相色谱、核磁、红外等表征方法研究其反应机理。研究表明,液态小分子聚碳硅烷的Si—H基团受热分解所形成的自由基,部分相互偶联,另一部分则与钛酸丁酯发生自由基取代反应,从而形成含钛聚碳硅烷,并因链的增长,分子量相应增大,最终形成主分子链由支化或交联度较高的链段所组成的含钛聚碳硅烷,具有较高的陶瓷产率,可以用作SiC陶瓷的先驱体。     

不饱和聚碳硅烷的研究进展

不饱和聚碳硅烷因其主链结构中具有硅和共轭基团交错的结构,具有良好的热稳定性、可溶性、易加工、低毒性等系列重要的物理和化学性质,在半导体材料、有机电致发光材料、陶瓷前驱体、耐热材料、光伏材料等诸多领域显示出广阔的应用前景,因此针对不饱和聚碳硅烷的研究一直是有机硅高分子领域的研究热点。总结了近年来不饱和聚碳硅烷的研究进展的同时,对不饱和聚碳硅烷的合成方法进行了详细综述,包括硅氢加成反应、Heck反应及Wittig反应等,并介绍了不饱和聚碳硅烷在光电材料、电致发光等方面的应用情况。     

不同碳链长度的硅烷偶联剂对纳米SiO2改性研究

使用不同碳链长度的硅烷偶联剂(甲基三甲氧基硅烷、丙基三甲氧基硅烷、辛基三甲氧基硅烷、十六烷基三甲氧基硅烷)分别对纳米SiO₂进行改性。采用FTIR、XPS、XRD、TGA等表征方法研究了SiO₂粒子改性前后的化学结构和接枝率;采用激光粒度测试和TEM研究了纳米SiO₂颗粒的粒径分布和微观形貌;采用沉降实验和接触角观察了纳米SiO₂粒子的水中分散性状态及其亲疏水性能。结果表明,硅烷偶联剂成功接枝在了纳米SiO₂颗粒表面。随着硅烷偶联剂碳链长度的增加,改性后SiO₂平均粒径呈现先减小后增大的趋势,团聚现象减弱。经十六烷基三甲氧基硅烷改性的纳米SiO₂颗粒接触角从11.7°提高至108.2°,由亲水性转变为疏水性。     

含前驱体SiC粉体低压成型低温烧结SiC多孔陶瓷

采用聚碳硅烷和SiC粉体为原料低压成型低温烧结制备SiC多孔陶瓷,研究了聚碳硅烷含量对SiC多孔陶瓷性能的影响。SEM分析表明,聚碳硅烷裂解产物将SiC颗粒粘结起来,多孔陶瓷具有相互连通的开孔结构。烧成SiC多孔陶瓷的孔隙孔径为单峰分布、分布窄,室温至800℃之间多孔陶瓷的平均热膨胀系数为4.2×10-6 K-1。随着聚碳硅烷含量的增大,SiC多孔陶瓷的孔隙率降低、三点弯折强度增大,当聚碳硅烷质量分数为10%时分别为44.3%和31.7MPa。     

国外有机硅树枝状化合物的应用进展

有机硅树枝状化合物是以Si-O、Si-C、Si-Si等键为骨架，具有三维立体结构类似于树枝形状的化合物。结合当今国外该领域的最新进展系统地介绍了国外有机硅树枝状化合物的最新应用。     

耐热聚硅碳烷的合成及性质

本文介绍了两种耐热聚硅碳烷(聚二苯基硅甲撑和MPS树脂)的合成方法及主要性质。     

Polysilane-derived porous SiC preforms for the preparation of SiC-glass composites

Three different types of SiC preforms, with open porosities between 60 and 70%, were prepared by pyrolysis of polysilanes and polycarbosilanes at 1670 K. some samples of each type of SiC structure were oxidized in air at 1070 K to promote wetting by the glass melt. Preforms were then applied for gas pressure infiltration with an alumosilicate glass melt at 1670 K in 3 MPa argon, and the influence of pore-size distribution and surface composition on infiltration time was investigated. The composition of the precursors was determined by chemical analysis, and pyrolysed SiC was analysed by thermal decomposition. The porosity and pore-size distribution of the SiC-preforms were measured on photographs of sample cross-sections. The SiC-glass composites were examined by light microscopy, scanning electron microscopy and electron scanning microanalysis.     

“String and bead” model of copper modified polycarbosilane: synthesis and applications

Journal of Materials Science - The synthesis of metal modified polycarbosilanes is currently an area of significant activity. These polymers can be processed to advanced materials such as ceramic...     

液态超支化聚碳硅烷的研究进展

液态超支化聚碳硅烷(HBPCS)因具良好的流动性和可自交联性,适用于制备SiC陶瓷基复合材料而倍受青睐。对它的合成、交联、陶瓷化和应用探索等方面的研究动态进行了综述,并展望了其今后的发展趋势。     

聚合物先驱体材料体系的陶瓷化研究进展与展望

分析了先驱体转化陶瓷法制备陶瓷涂层的优缺点,阐述了高陶瓷产率聚合物先驱体制备陶瓷涂层的研究现状,分析了聚合物先驱体制备陶瓷涂层存在的问题,提出了探索新的可控制备高质量陶瓷涂层的方法与技术,研制高陶瓷产率的裂解材料体系,注重裂解材料体系的复合化发展和不断完善裂解形成陶瓷涂层的机理是今后需要重点发展的方向。     

Conversion process of chlorine containing polysilanes into silicon carbide: Part I Synthesis and crosslinking of poly(chloromethyl)silanes–carbosilanes and their transformation into inorganic amorphous silicon carbide

Synthesis of chlorine containing polysilanes by catalytic redistribution is described and the obtained polymers are characterized by infrared (IR)-, magic angle spinning nuclear magnetic resonance (MAS-NMR)-spectroscopy and elemental analysis. The pyrolysis of such polysilanes was investigated by thermoanalysis, IR-, MAS NMR- and electron spin resonance (ESR)-spectroscopy. The conversion process from polysilane into polycarbosilane is described in terms of the results of the performed investigations and a model of the process is developed. Differences between this conversion process and those for chlorine free polysilanes or polycarbosilanes previously described by other authors are discussed. This revised version was published online in November 2006 with corrections to the Cover Date.     

Conversion process of chlorine containing polysilanes into silicon carbide

The crystallization of pyrolysed chlorine containing polycarbosilanes (PCS) into silicon carbide is suggested to begin at about 1000 °C by X-ray diffraction experiments. The crystallite size and the crystallite amount were also estimated from the X-ray diffraction patterns. Electron spin resonance, nuclear magnetic resonance and Raman-spectroscopy were used to describe the structure of the material. In addition to these methods a combustion method was used to investigate the carbon and the oxygen contents.     

Anorganische Fasern. Herstellung,Eigenschaften und Verwendung

Inorganic Fibres – Fabrication, Properties and Application Glass- and carbon fibres are preferred reinforcement materials for composites with polymer matrix. Basing on an analysis of their properties it is shown that other inorganic fibres can combine the advantages of both, and avoid their disadvantages. Boron-, siliconcarbide- and alumina-fibres are discussed in detail. The boron fibre has a YOUNG's modulus up to 45 MN/m² and a strength of 3000–4000 MN/m² as well as high compressive and shear strength. Therefore the boron fibres are superior to the carbon fibres as high modulus reinforcement material. The disadvantages of the boron fibres are their complicated fabrication process (chemical vapour deposition on a tungsten monofilament), and their only availability in form of monofilaments with diameters of at least 60 μm. The boron fibre recristallizes at 6000 °C and reacts also with the tungsten substrat. Thus, its application at elevated temperatures is limited. The SiC-fibre shows the same mechanical properties as the boron fibre but it can be fabricated by chemical vapour deposition also on a carbon monofilament. The advantages are the chemical compatibility with carbon substrat and the resistance against oxidation. The disadvantage is the higher density compared with that of boron (3,5 against 2,6 · 10³ kg/m³) Carbon yarns (with 10 000 monofilaments of 10 μm diameter) with SiC coatings of 0,5 μm can be seen as an alternative to the relatively thick SiC-monofilaments with 60 μm diameter. The advantage of such coated carbon yarn is a better applicability in fibre reinforced composite materials. There exists a further alternative preparation process for SiC-yarn, namely the spinning of polycarbosilanes with subsequent formation of SiC by pyrolysis treatment. Al₂O₃-fibres are chemically inert against most oxidic and metallic matrix materials, and promises to be candidate reinforcement materials for aluminium. They can be prepared by melt-spinning process as well as by a hydrolysis-process starting from aluminium organic compounds with subsequent heat treatment for thermal decomposition. The properties of all these fibre materials are compared with those of glass-, polyamid- and carbon-fibres as well as with metal wires.