有机-无机杂化纳米结构体——多面体低聚硅倍半氧烷研究进展

多面体低聚硅倍半氧烷是基于化学键合作用形成的分子内杂化体系,其改性后的材料是一类具有广泛潜在应用价值的新型有机-无机杂化材料。介绍了多面体低聚硅倍半氧烷单体的结构、性能、单体及其衍生物的合成,以及其改性聚合物材料在航空、航天、生物、电子等高科技领域内的应用前景。针对国内的研究现状,指出低聚硅倍半氧烷-聚合物杂化体系研究所存在的问题。     

EP/环氧基苯基多面体低聚硅倍半氧烷复合物的制备及其性能

通过水解缩合反应合成了环氧基苯基多面体低聚硅倍半氧烷(cy-ep-Ph-POSS),并制备了环氧树脂(EP)/cy-ep-Ph-POSS复合物,研究了复合物的热性能、力学性能以及阻燃性能.结果表明:cy-ep-Ph-POSS主要由含有6,8,10个硅原子的多面体低聚硅倍半氧烷结构组成;与纯EP相比,EP/cy-ep-P...     

多面体低聚倍半硅氧烷的最新研究进展

综述了多面体低聚倍半硅氧烷(POSS)的研究进展,主要介绍了它的常见结构、特性、合成方法和应用,展望了POSS合成研究的发展趋势。     

多面体低聚倍半硅氧烷合成的研究进展

介绍了多面体低聚倍半硅氧烷(POSS)的分类、结构和性能,POSS是基于化学键合作用而形成的一种分子水平上的纳米有机/无机杂化体,具有规整的立体结构、纳米尺度、优良的相容性和修饰性,其独特的纳米笼形结构使之成为分子结构设计和材料改性的最佳选择。综述了POSS的合成方法及研究进展,如三官能度硅烷或四官能度硅烷在酸、碱或有机盐催化下通过水解缩合反应合成POSS;以POSS为母体,通过封角闭环法和官能团转化衍生法合成POSS;点击化学法制备POSS等。比较了各种方法的优点和存在的问题,指出目前国内POSS的研究重点是合成带有高活性的POSS单体,改进合成路线及工艺,为其工艺化提供技术支持。     

低聚硅倍半氧烷在HTPB复合推进剂中的多功能作用

为提升复合固体推进剂的综合性能,将不同质量分数的八苯基硅倍半氧烷(OPS)、八氨基苯基硅倍半氧烷(OAPS)、八硝基苯基硅倍半氧烷(ONPS)和八(二硝基苯基)硅倍半氧烷(ODNPS)等4种有机-无机杂化结构的多面体低聚硅倍半氧烷(POSS)加入端羟基聚丁二烯(HTPB)推进剂中。使用电子万能试验机、热机械分析仪测定推进剂的拉伸力学性能;使用氧弹量热仪测定推进剂在3MPa氮气下的爆热;利用线扫描摄像燃速测定系统测定了推进剂的燃速—压强关系;采用扫描电镜、激光粒度仪和X射线衍射仪(XRD)对推进剂爆热测试后的凝聚相燃烧产物进行微观形貌、粒度及物相分析;采用同步热分析仪、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱仪(XPS)等对POSS影响推进剂燃烧的机理进行了分析。结果表明,4种POSS均可增强推进剂的拉伸力学性能,八氨基苯基硅倍半氧烷(OAPS)效果最优;4种POSS均可提高推进剂的燃速,ONPS质量分数为3%时,推进剂燃速及爆热最高;4种POSS均可促进推进剂铝燃烧,明显减小凝聚相燃烧产物的粒径,ODNPS效果最优。分析认为,ONPS和ODNPS热解、燃烧产生的纳米尺寸...     

多面体低聚倍半硅氧烷的研究进展

介绍了多面体低聚倍半硅氧烷(POSS)的基本特性以及常用的5种制备方法。指出了POSS在多孔材料、高性能高分子材料、光固化树脂、电子材料以及航空与空间等领域的应用情况。对POSS在发展过程中存在的一些问题进行了分析并展望了其今后的发展趋势。     

聚(乙烯基)硅倍半氧烷的结构表征

以乙烯基三乙氧基硅烷为原料,通过控制水解聚合条件制得聚(乙烯基)硅倍半氧烷。IR光谱表征产物中形成了Si—O—Si的骨架结构,29SiNMR表征说明产物是以笼形结构为主,用GPC测得的摩尔质量接近五面体(T6)和六面体(T8)结构的笼形聚(乙烯基)硅倍半氧烷;通过对产物平均几何参数的计算,确定产物为笼形T6结构的聚(乙烯基)硅倍半氧烷。     

多面体低聚倍半硅氧烷及多面体低聚倍半硅氧烷-聚合物的研究进展

综述了多面体低聚倍半硅氧烷(POSS)的结构、性质与合成方法,重点介绍了单官能团、双官能团、多官能团3类POSS可以通过共聚、缩聚、接枝、共混等多种方式引进聚合物中,形成真正的有机/无机纳米杂化材料,最后指出了POSS的发展方向.     

多面体低聚倍半硅氧烷在聚合物中的应用

多面体低聚倍半硅氧烷(POSS)具有特殊的纳米级笼形结构,与聚合物有良好的结合性和相容性,采用POSS改性聚合物可制备分子级分散的纳米复合材料。介绍了POSS的结构及特性,并综述了POSS在聚合物中的应用及研究进展。     

多面体低聚倍半硅氧烷改性PU的制备

采用多面体低聚倍半硅氧烷(POSS)对聚氨酯(PU)进行改性,并对改性PU的性能进行研究。结果表明:采用超声波分散法可将POSS均匀分散在PU基体中;八乙烯基POSS对PU具有较好的补强和增韧作用,而八苯基POSS对PU的补强作用不明显。     

离子型聚合反应机理制备聚合物/POSS纳米杂化材料的研究进展

多面体低聚倍半硅氧烷（POSS,Polyhedral Oligomeric Silsesquioxane）作为一种特殊的有机/无机杂化纳米粒子备受关注。本文综述了国内外通过离子型反应机理制备聚合物/POSS纳米杂化材料的一些进展,着重介绍反应机理、特点,并对这一领域的前景进行了展望。     

八乙烯基多面体低聚倍半硅氧烷的合成与表征

采用水解缩合法,在浓HCl为催化剂的条件下,以乙烯基三甲氧基硅烷为原料合成了八乙烯基多面体低聚倍半硅氧烷,并对合成产物进行了表征;研究了反应温度、反应物的投料比对产物收率的影响.结果表明,在25 ℃,反应物水解缩合21 d,乙烯基三甲氧硅烷、HCl、CH3OH三者的体积比为9∶ 12∶ 200,乙烯基三甲氧基硅烷、HCl的体积分数分别为3.90%、5.43%时,产物的收率达到最高,为26.3%.     

Polysiloxanes containing polyhedral oligomeric silsesquioxane groups in the side chains; synthesis and properties

Linear polysiloxanes having different amounts of polyhedral oligomeric silsequioxane (POSS) side groups were prepared from the hydrosilylation reaction of poly(ethylhydrosiloxane) with different amount of POSS and 1-octene using platinum(0)-divinyl tetramethyldisiloxane as a catayst. 1-Octene and platinum(0)-divinyl tetramethyldisiloxane were found to be very important for the preparation of the linear polymer without any cross-linked structures. The linear polysiloxanes with POSS side groups are soluble in various organic solvents. When the content of POSS-containing monomeric unit is larger than 10 mol%, free standing films can be prepared from a routine solution casting method, although this polysiloxane is not cross-linked.     

多面体低聚硅倍半氧烷环氧化物的合成研究

用过氧乙酸氧化三乙烯基POSS(多面体低聚硅倍半氧烷)单体制备了POSS环氧化物,通过核磁共振和傅立叶变换红外光谱分析三乙烯基POSS环氧化前后结构的变化,研究并讨论了H2O2浓度、乙酸含量、反应温度、反应时间对三乙烯基POSS环氧化反应的影响.结果表明三乙烯基POSS环氧化的适宜条件是H2O2浓度50%(质量分数),反应温度70℃,CH3COOH与H2O2摩尔比0.51,反应时间h时.     

Epoxy hybrid composites cured with octaaminophenyl polyhedral oligomeric silsesquioxane

Polyhedral oligomeric silsesquioxane-containing hybrids of epoxy resins are prepared via the cocuring reaction between octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) and brominated epoxy resin (EP). The gel time, dispersion, thermal properties, mechanical properties, water absorption, and dielectric properties of the OAPS/EP composites are studied. The gel time of the 1 wt % OAPS composites is significantly higher compared with that of the epoxy resin control. Wide angle X-ray diffraction and scanning electron microscopy show that, at the molecular level, the appropriate amount of POSS cages was dispersed in the epoxy matrix because the POSS monomer participated in the crosslinking reaction. The thermal and mechanical properties of the composites are enhanced as 1 wt % OAPS was added to the epoxy system. The water absorption of the 1 wt % OAPS composite significantly declines. The dielectric constant of the 1 wt % OAPS composite is 0.5 less than that of the epoxy resin control in the range of 100 Hz–40 MHz. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Polyimide and polyhedral oligomeric silsesquioxane nanocomposites for low-dielectric applications

A novel polyimide (PI) hybrid nanocomposite containing polyhedral oligomeric silsesquioxane (POSS) with well defined architecture has been prepared by copolymerization of octakis(glycidyldimethylsiloxy)octasilsesquioxane (Epoxy-POSS), 4,4′-oxydianiline diamine (ODA), and 4,4′-carbonyldiphthalic anhydride (BTDA). In these nanocomposite materials, the equivalent ratio of the Epoxy-POSS and ODA are adjustable, and the resultant PI-POSS nanocomposites give variable thermal and mechanical properties. More importantly, we intend to explore the possibility of incorporating POSS moiety through the Epoxy-POSS into the polyimide network to achieve the polyimide hybrid with lower dielectric constant (low-k) and thermal expansion. The lowest dielectric constant achieved of the POSS/PI material (PI-10P) is 2.65 by incorporating 10 wt% Epoxy-POSS (pure PI, k=3.22). In addition, when contents of the POSS in the hybrids are 0, 3, 10 wt% (PI-0P, PI-3P, PI-10P), and the resultant thermal expansion coefficients (TEC) are 66.23, 63.28, and 58.25 ppm/°C, respectively. The reduction in the dielectric constants and the resultant thermal expansion coefficients of the PI-POSS hybrids can be explained in terms of creating silsesquioxane cores of the POSS and the free volume increase by the presence of the POSS-tethers network resulting in a loose PI structure.     

ABA triblock copolymers containing polyhedral oligomeric silsesquioxane pendant groups: synthesis and unique properties

The synthesis and characterization of POSS containing ABA triblock copolymers is reported. The use of atom transfer radical polymerization (ATRP) enabled the preparation of well-defined model copolymers possessing a rubbery poly(n-butyl acrylate)(pBA) middle segment and glassy poly(3-(3,5,7,9,11,13,15-heptaisobutyl-pentacyclo[9.5.1.1^3,9.1^5,15.1^7,13]-octasiloxane-1-yl)propyl methacrylate(p(MA-POSS)) outer segments. By tuning the relative composition and degree of polymerization (DP) of the two segments, phase separated microstructures were formed in thin films of the copolymer. Specifically, dynamic mechanical analysis and transmission electron microscopy (TEM) observations reveal that for a small molar ratio of p(MA-POSS)/pBA (DP=6/481/6) no evidence of microphase separation is evident while a large ratio (10/201/10) reveals strong microphase separation. Surprisingly, the microphase-separated material exhibits a tensile modulus larger than expected (ca. 2×10⁸ Pa) for a continuous rubber phase for temperatures between a pBA-related T_g and a softening point for the p(MA-POSS)-rich phase. Transmission electron microscopy (TEM) images with selective staining for POSS revealed the formation of a morphology consisting of pBA cylinders in a continuous p(MA-POSS) phase. Thermal studies have revealed the existence of two clear glass transitions in the microphase-separated system with strong physical aging evident for annealing temperatures near the T_g of the higher T_g phase (p(MA-POSS). The observed aging is reflected in wide-angle X-ray scattering as the strengthening of a low-angle POSS-dominated scattering peak, suggesting some level of ordering during physical aging. The T_g of the POSS-rich phase observed in the microphase separated triblock copolymer was nearly 25 °C higher than that of a POSS-homopolymer of the same molecular weight, suggesting a strong confinement-based enhancement of T_g in this system.     

笼状硅氧烷低聚物/聚合物复合材料的研究进展

介绍了笼状硅氧烷低聚物（POSS）的概念、分类及其合成工艺,综述了POSS／聚合物复合材料的制备方法及其在提高聚合物在热稳定性、阻燃性能、医学性能、光电性能、形状记忆及表面性能等方面的应用。