多面体低聚倍半硅氧烷的合成研究进展

首先介绍了多面体低聚倍半硅氧烷(POSS)的结构、分类和性质,然后综述了三官能度硅烷或四官能度硅烷在酸、碱和有机盐催化下通过水解缩合反应合成POSS的研究进展,以及以POSS为母体、通过封端关笼法、闭环法和官能团转化法合成POSS的研究进展。     

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。     

多面体低聚倍半硅氧烷在涂料领域的研究进展

多面体低聚倍半硅氧烷(POSS)作为一种有机无机杂化纳米材料,由于其独特的结构特性及改善涂料综合性能的优势而备受关注。本文介绍了POSS的结构和特性,综述了POSS的合成方法,根据官能团数量的不同将合成方法分为3种;分析了POSS改性聚合物的方式以及其改性聚合物在涂料领域的研究进展,通过POSS的改性可以提高涂料的热稳定性、力学性能、阻燃性能等,并展望了其发展趋势。     

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。     

多面体低聚倍半硅氧烷研究的最新进展

多面体低聚倍半硅氧烷（POSS）是目前研究相当活跃的一类有机—无机杂化结构的纳米粒子。通过官能化POSS直接聚合或利用化学反应将POSS结合到聚合物中以及作为纳米添加剂与其他材料共混,可制备多种多样的聚合物/POSS纳米复合材料。POSS的引入能有效降低材料的介电常数,改善材料的热性能、机械性能、耐火性、防水防油性、加工性能、牢固度和透明度等;因此,POSS被认为是一种优良的纳米构筑材料。本文对POSS研究的近况进行了简要概述。     

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改性聚合物材料研究进展

介绍了多面体低聚倍半硅氧烷(POSS)的特性及POSS的3种基本制备方法,综述了POSS改性聚合物的最新研究进展(包括POSS改性聚烯烃、聚丙烯酸酯、聚酰亚胺、环氧树脂等)及POSS改性聚合物作为阻燃材料、耐热材料、光电材料、膜材料等的应用,指出了POSS材料的研究与应用前景.     

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。     

多面体低聚倍半硅氧烷材料改性硅树脂的研究进展

硅树脂兼具有机材料和无机材料的特点,被广泛应用于电绝缘漆、涂料、粘接剂和塑料等领域,但硅树脂起始分解温度较低,限制了其进一步应用。多面体低聚倍半硅氧烷(POSS)是一类由硅氧骨架组成,具有纳米级三维立体空间结构的杂化分子,其作为添加剂能有效改善硅树脂的力学性能和耐热性能。本文主要介绍了POSS改性硅树脂的不同方法,综述了POSS材料在硅树脂改性领域的研究进展。     

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%.     

多面体低聚硅倍半氧烷的研究进展

综述了多面体低聚硅倍半氧烷（POSS）的结构特性和合成方法，重点介绍了同取代基、单官能度、双官能度、多官能度四类POSS的合成方法，比较了各种合成方法的优劣，展望了POKS合成研究的发展方向。     

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/anhydride networks modified with polyhedral oligomeric silsesquioxanes

Epoxy/anhydride networks were modified, in the presence of benzyldimethylamine as catalyst, with two polyhedral oligomeric silsesquioxanes (POSS), whose inorganic framework had a compact and stable Si‐O core and an organic substituent shell. The influence of the content and type of POSS during curing and on the properties of the thermosets was investigated by thermal analysis and infrared spectroscopy. The curing kinetics was analyzed by means of an integral isoconversional nonisothermal procedure. When the POSS modifier was added, the storage modulus in the rubbery plateau increased and the glass transition temperature decreased because of the presence of the flexible organic moieties and the influence in the crosslinking density. The presence of these POSS structures hardly affected the thermodegradation behavior of cured materials. The dispersion of the POSS structures in the epoxy/anhydride matrix was good, but some submicron‐sized POSS agglomerates could be observed by transmission electron microscopy. POLYM. COMPOS., 2013. © 2012 Society of Plastics Engineers     

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.     

多面体低聚倍半硅氧烷在环氧树脂改性中的应用进展

综述了近几年多面体低聚倍半硅氧烷(POSS)在环氧树脂改性中的应用。POSS单独修饰环氧树脂,可提高其力学性能及热稳定性能;POSS协同9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物等功能性分子一起修饰环氧树脂,可增强其阻燃性能;POSS与碳纳米管、石墨烯等纳米材料共同修饰环氧树脂,可提高纳米材料在环氧树脂中的分散性,改善纳米复合材料的导电能力和黏结强度等性能;POSS与纤维共同修饰环氧树脂,可有效增强纤维与环氧树脂间的界面性能。最后展望了POSS修饰改性环氧树脂的未来方向:开发更简易的引入方式,引入更多样的官能分子,协同多种纳米材料修饰环氧树脂。     

Synthesis and characterization of polyhedral oligomeric silsesquioxane-based waterborne polyurethane nanocomposites

A series of aqueous polyurethane nanocomposites were prepared using various amounts (0.3-4.6 wt%) of a diol functionalized polyhedral oligomeric silsesquioxane (POSS) by the prepolymer mixing method. N,N-bis(2-hydroxy ethyl-2-amino ethane sulfonic acid sodium salt (BES sodium salt) was used as the anionic internal emulsifier and ionic center. The molecular structure of the samples was characterized by ATR-FTIR spectroscopy. We investigated the effect of the POSS contents on the properties of the specimens by particle size and viscosity measurements, X-ray diffractometry, mechanical behavior assessment, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis and morphological studies. The results showed that with increasing the POSS contents, particle size, viscosity, tensile strength, modulus, T _g , and thermal stability of the synthesized samples were improved. Also, SEM and TEM images indicated that a homogeneous morphology was obtained in the 1.2 wt% POSS-based sample. AFM results showed that the surface roughness increased as the POSS amounts increased.     

Synthesis and characterization of polyhedral oligomeric azido‐octaphenylsilsesquioxane

Polyhedral oligomeric azido‐octaphenylsilsesquioxane (N₃‐OPS) was synthesized from octaaminophenylsilsesquioxane (OAPS) via its diazonium salt. The synthesis included nitration of octaphenylsilsesquioxane (OPS) to octanitrophenylsilsesquioxane (ONPS), conversion of ONPS into octaaminophenylsilsesquioxane (OAPS), and conversion of OAPS into N₃‐OPS. The kinetics of the conversion of OAPS into N₃‐OPS were studied by recording the volume of N₂ gas released with the reaction time, which revealed it to be a 1st order reaction. The chemical structures of ONPS, OAPS and N₃‐OPS were characterized by ¹H‐NMR, GPC, FTIR, ²⁹Si solid NMR, ¹³C‐NMR, XRD, and elemental analysis. It is proposed that the diazonium salt of OAPS was substituted by the main ? N₃ group and a few of the ? OH groups. The ratio of ? N₃:? OH was calculated to be approximately 68:32 in N₃‐OPS on the basis of the elemental analysis and ¹H‐NMR. XRD suggested that N₃‐OPS was a kind of amorphous compound. The two‐step conversion mechanism of OAPS to N₃‐OPS was briefly discussed. TGA results showed that N₃‐OPS was stable at ambient temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012