二乙烯基苯/聚二甲基硅烷改良聚碳硅烷合成工艺的研究

在传统的合成体系中加入适量的二乙烯基苯,通过常压高温自由基聚合反应,获得了产率较高、可纺性优良的先驱体聚碳硅烷。采用正交实验设计研究了反应温度、升温速率、二乙烯基苯的质量分数、裂解温度和保温时间五个因素对聚碳硅烷产率的影响。方差分析表明,在反应温度为420℃、二乙烯基苯的质量分数为1·5%、升温速率为6℃/h、裂解温度为530℃、保温时间为5h条件下,可以得到粗产率为50%的黄色透明固态聚碳硅烷;各因素对聚碳硅烷产率影响的显著性依次为:升温速率>反应温度>二乙烯基苯的质量分数>保温时间>裂解温度。     

氯铂酸催化剂在聚碳硅烷与二乙烯基苯交联中的应用

为了提高聚碳硅烷与二乙烯基苯(polycarbosilane/divinylbenzene,PCS/DVB)硅氢化交联反应程度,采用改性氯铂酸催化的方法对PCS/DVB交联进行了研究.研究表明:氯铂酸催化性能与其用量、交联温度、以及PCS相对分子量有关.当固体PCS相对分子量低于1 500,该反应中氯铂酸催化剂的用量为12.5×10-6,低分子量PCS中Si-H含量较高,且分子链支化程度低,易发生硅氢化反应;高分子量PCS中Si-H含量较低,且分子链自身支化程度高,活性基团被包裹于大分子链中,其Si-H键参加反应空间位阻大.氯铂酸催化剂在低温下催化作用不明显,催化交联的反应温度在150℃以上.     

聚二甲基硅烷合成聚碳硅烷的研究

以聚二甲基硅烷为原料,采用正交设计的方法研究了常压高温裂解重排法中反应温度,裂解温度,保温时间对聚碳硅烷结构的影响,结果发现,该合成方法的最佳工艺条件为：反应温度470－475℃,裂解温度560℃,保温时间6h,3个因素对聚碳硅烷的显著性影响顺序为：反应温度＞保温时间＞裂解温度,从聚二甲基硅烷出发合成的先驱体聚碳硅烷的支化度较低,可纺性好。     

用不同分子量聚碳硅烷制备含铝聚碳硅烷

分别选用分子量Mn为929、1 050、1 186的聚碳硅烷(polycarbosilane,PCS)与乙酰丙酮铝反应制备含铝聚碳硅烷(polyaluminocarbosilanes,PACS),研究PCS分子量对PACS性能及结构的影响.结果表明:随着PCS分子量的增加,PACS分子量逐渐增加,分布加宽,而活性基团Si-H键含量没有明显变化;随着PCS分子量增加,PACS陶瓷产率增加.将不同的PACS进行热交联,其陶瓷产率明显提升,增长幅度随PCS分子量增大而增大.PACS的纺丝性能随PCS分子量增大而降低.     

聚碳硅烷可纺性与纺丝工艺探讨

本文研究了聚碳硅烷的特性与其可纺性的关系,并对连续聚碳硅烷原丝制备过程中的纺丝温度、纺丝压力、过滤方式、气流收丝方式与速度等进行了探讨。     

氯铂酸催化剂在聚碳硅烷与二乙烯基苯交联中的应甩

为了提高聚碳硅烷与二乙烯基苯(polycarbosilane/divinylbenzene,PCS/DVB)硅氢化交联反应程度,采用改性氯铂酸催化的方法对PCS/DVB交联进行了研究。研究表明:氯铂酸催化性能与其用量、交联温度、以及PCS相对分子量有关。当固体PCS相对分子量低于1500,该反应中氯铂酸催化剂的用量为12.5×10-6,低分子量PCS中Si—H含量较高,且分子链支化程度低,易发生硅氢化反应;高分子量PCS中Si—H含量较低,且分子链自身支化程度高,活性基团被包裹于大分子链中,其Si—H键参加反应空间位阻大。氯铂酸催化剂在低温下催化作用不明显,催化交联的反应温度在150℃以上。     

液态聚碳硅烷制备含铝碳化硅陶瓷前驱体——聚铝碳硅烷

通过液态聚碳硅烷与乙酰丙酮铝反应,合成了一系列的聚铝碳硅烷,考察了原料配比和反应温度的影响.结果显示:改变合成温度或乙酰丙酮铝的加入量,聚铝碳硅烷呈现从液态到固态的转变.增加乙酰丙酮铝的配比或提高合成温度,可增加聚铝碳硅烷中铝的质量分数,在360℃合成的产物中铝的质量分数接近理论值;增加铝的质量分数或提高合成温度,可增大聚铝碳硅烷的分子量及其多分散系数.360℃以下聚铝碳硅烷的数均分子量随着铝的质量分数的增加呈线性增加.红外光谱及核磁共振分析结果均显示,铝元素的引入伴随着Si-H键的消耗,通过AlO_x(x=4,5,6)基团使液态聚碳硅烷分子部分交联长大,高铝含量的样品具有较高的交联程度.     

聚铝碳硅烷的制备及应用进展

介绍了碳化硅（SiC）陶瓷纤维、含铝SiC陶瓷纤维的特点,综述了用聚碳硅烷、聚硅碳硅烷、聚二甲基硅烷与乙酰丙酮铝反应制备聚铝碳硅烷先驱体的合成方法,聚铝碳硅烷的化学结构及在制备耐超高温陶瓷纤维和发光陶瓷薄膜中的应用,评述了各种制备工艺的优缺点,提出了当前工作中需要解决的问题,并展望了今后的发展趋势。     

聚碳硅烷/二乙烯基苯粘度特性研究

通过粘度实验,研究了20～140℃温度范围内浸渍用聚碳硅烷(PCS)/二乙烯基苯(DVB)体系流变学性质。PCS在DVB中以溶解和熔融的方式分散,温度为影响体系粘度的关键因素。结果表明PCS/DVB体系在80～120℃的温度范围内,粘度低于300mPa·s,可满足浸渍要求。     

超高分子质量聚碳硅烷的合成与表征

从常压合成得到的中低分子量PCS出发进行热压合成制备超高分子质量的PCS,并对其结构和性能进行了表征。研究表明控制热压反应温度在460~470℃、预加压力1~2 MPa、反应6h时得到先驱体PCS的Mw为6 400~8 500;热压合成后制得的超高分子质量PCS的Si—H含量和支化度有所降低;通过控制热压反应时间可以较好的调控超高分子PCS的重均分子质量的大小。     

先驱体聚碳硅烷的合成研究进展

介绍了近年来先驱体聚碳硅烷(PCS)的制备、性能和应用的研究现状和进展。着重介绍了合成先驱体PCS的主要方法：常压循环热裂解法、高压法、常压催化法和常压高温裂解法。比较了这几种合成方法的优缺点：从用PCS制备陶瓷纤维的用途来说，高压法是一种较成熟的方法，所制备的陶瓷SiC纤维的性能也较好，但装置复杂、成本较高、安全性较差；常压高温裂解法合成装置简单、成本较小、安全性也好，但使用该法制得的陶瓷SiC纤维的性能较差。     

Synthesis,characterization, and UV curing kinetics of hyperbranched polycarbosilane

Hyperbranched polycarbosilane with allyl end groups was synthesized via hydrosilylation of methyldiallyldilane, and characterized by Fourier transform infrared spectroscopy, ¹H, ¹³C, ²⁹Si nuclear magnetic resonance, and size exclusion chromatography/multiangle laser light scattering. The degree of branching and average number of branches of the resulted polymer determined by ²⁹Si NMR spectroscopy is 0.58 and 0.42, and the exponent α in Mark–Houwink equation is 0.33 based on the relationship between viscosity and molecular weight. UV curing behaviors of the hyperbranched polycarbosilane were investigated using differential scanning photocalorimeter, and the effects of diluent's concentration, light intensity, reaction atmosphere, and temperature on the curing behaviors and kinetics were studied in detail. It was found that curing reaction can be accomplished rapidly under UV irradiation within 40 s both in air and in nitrogen atmosphere if acrylic reactive diluent was employed. The result suggests that it is an effective way to increase the curing reactivity by incorporating acrylic reactive diluents with high UV sensitivity into the polycarbosilane system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

A propargyl‐substituted polycarbosilane (PCS), namely, propargyl‐substituted hyperbranched hydrodipolycarbosilane (PHPCS), was prepared by a modified synthesis route, which involved Grignard coupling of partially methoxylated Cl₃SiCH₂Cl and CHCCH₂Cl, followed by reduction with lithium aluminum hydride. The resultant PHPCSs were characterized by gel permeation chromatography, Fourier transform infrared (FTIR) spectroscopy, and NMR. Moreover, the thermal properties of the PHPCSs were investigated by thermogravimetric analysis. The ceramic yield of PHPCS at 1400°C was about 82.5%, which was about 10 wt % higher than that of hyperbranched hydrodipolycarbosilane without the substitution of propargyl groups. The PHPCS‐derived ceramics were characterized by X‐ray diffraction (XRD), FTIR spectroscopy, and elemental analysis. The XRD and FTIR results indicate that the heat treatment significantly influenced the evolution of crystalline β‐SiC. It can be convenient to get near‐stoichiometric ceramics from PHPCS through the control of feed ratios of the starting materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:3400–3406, 2011     

Si-C fiber prepared from polycarbosilane cured without oxygen

A new curing method for polycarbosilane was developed. In this method, halogenated hydrocarbon or unsaturated hydrocarbon vapor was used as curing agent. Si-C fiber with a small amount of oxygen was prepared from polycarbosilane fiber cured without introducing oxygen. The structure and the properties of the fiber are discussed in comparison with Si-C-O fiber obtained from thermal-oxidized polycarbosilane fiber. Using the new curing method, the thermal stability of the Si-C fiber was far improved with respect to that of conventional Si-C-O fiber.     

聚碳硅烷的高温高压生成机理研究II蒸馏产物的结构分析

以液态聚硅烷(LPS)在450℃反应得到的聚碳硅烷(PCS)粗产品为原料,经溶解、过滤、热处理后减压蒸馏,收集蒸馏馏分并进行表征,由此推出不同摩尔质量的PCS的典型结构,进而推测出LPS转化为PCS分子的机理是:随着温度的升高,LPS中的Si—Si键发生断裂、重排,转化为Si—C键,生成低分子碳硅烷;随着温度的继续升高,碳硅烷分子间发生脱氢、脱甲烷缩合反应,摩尔质量逐渐长大,生成PCS。     

氨基长链烷烃共改性聚硅氧烷的合成

以α-蒎烯、甲基二氯硅烷、氯铂酸、甲醇、八甲基环四硅氧烷、N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷等为原料,通过硅氢加成反应、醇解反应和碱催化共聚反应合成了氨基蒎基改性聚硅氧烷。甲基二氯硅烷与α-蒎烯进行硅氢加成反应较佳的反应条件为反应温度80℃,甲基二氯硅烷与α-蒎烯的量之比1.1∶1,反应时间6h;采用石油醚为溶剂去除醇解反应产生的HCl。     

Synthesis and characterization of poly(1-sila-cis-pent-3-enes) substituted with pendant pyridinyl groups

Poly[1-methyl-1-[3-(3-pyridinyl)propyl]-1-sila-cis-pent-3-ene], poly[1-phenyl-1-[3-(3-pyridinyl)propyl)-1-sila-cis-pent-3-ene], and poly[1-phenyl-1-(4-pyridinyl)-1-sila-cis-pent-3-ene] were synthesized by the anionic ring-opening polymerization of 1-methyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, 1-phenyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, and 1-phenyl-1-(4-pyridinyl)-1-silacyclopent-3-ene, respectively. These are the first polycarbosilanes which contain heterocyclic pyridine units as side-chain substituents. These polymers were characterized by¹H,¹³C, and²⁹Si NMR as well as by IR and UV spectroscopy. The molecular weight distributions were determined by gel permeation chromatography, glass transition temperatures, by differential seanning calorimetry: (DSC) and thermal behavior, by thermogravimetric analysis. (TGA).     

Synthesis of new amphiphilic water‐stable hyperbranched polycarbosilane polymers

New amphiphilic hyperbranched polymers possessing hydrophobic skeletons and hydrophilic terminal groups have been prepared and characterized. The synthetic strategy involved the formation of a new stable matrix with aromatic units within a carbosilane backbone, as well as the use of a classical polycarbosilane matrix. Both of them with allyl groups on the surface have narrow polydispersity values. Molecular weight and polydispersity of the hyperbranched polymers were obtained using gel permeation chromatography with multi‐angle light scattering, and determination of the average number of functional groups present on the surface was achieved using ¹H NMR spectroscopy. The introduction of ionic groups was carried out via thiol–ene reactions with various thiol derivatives. The thermal properties of the polymers were also analysed using differential scanning calorimetry and zeta potential measurements. © 2013 Society of Chemical Industry