不完全缩合七苯基三羟基POSS的合成及表征

以苯为溶剂,40%苄基三甲基氢氧化铵的甲醇溶液为催化剂,苯基三氯硅烷水解缩合得到笼状八苯基多面低聚倍半硅氧烷,进一步在四乙基氢氧化铵(35%水溶液)的作用下,以四氢呋喃为溶剂,通过顶点-打开法合成不完全缩合的多面低聚倍半硅氧烷。利用1H、13C、29Si-NMR、FT-IR、元素分析、MALDI-TOF质谱等技术对产物的结构进行了表征,并采用TGA对其热稳定性进行了研究。结果表明,反应主产物为不完全缩合的七苯基三羟基多面低聚倍半硅氧烷,其初始分解温度(失重5%(wt))为516.1℃,热稳定性良好。与以往的合成方法相比,该法显著缩短了反应时间,并提高了产率,从而为POSS在纳米杂化材料领域的应用打下了基础。     

多面体低聚倍半硅氧烷对环氧树脂热性能影响分析

选用有机–无机纳米杂化材料乙烯环氧基多面体低聚倍半硅氧烷(EOVS)和环氧醚基多面体低聚倍半硅氧烷(GPOSS)为改性剂,与4,4′-二氨基二苯甲烷环氧树脂共混制得不同改性剂质量分数(树脂与改性剂总质量的百分数)的EOVS或GPOSS改性环氧树脂,考察了改性树脂的固化反应程度、玻璃化转变温度(Tg)和热稳定性。结果表明,当EOVS或GPOSS的质量分数为1%时,两种改性树脂的固化交联程度和Tg最高,Tg比未改性树脂分别提高了9.18℃和11.51℃;当EOVS质量分数为5%或GPOSS质量分数为1%时,改性树脂的热失重5%温度比未改性树脂提高6.24℃和8.1℃。在笼形结构的空间位阻和Si—O、Si—C等高键能化学键的综合作用下,多面体低聚倍半硅氧烷的引入可提高环氧树脂的热性能。     

多氨基倍半硅氧烷改性环氧树脂E-51固化动力学及热性能

以氯甲基笼型倍半硅氧烷(CM-POSS)为原料,与乙二胺通过取代反应合成多氨基倍半硅氧烷(POSS-NH2),并通过红外光谱(FT-IR)对产物进行表征.采用动态差示扫描量热法(DSC)和热失重分析(TGA)研究多氨基倍半硅氧烷( POSS-NH2)/环氧树脂(E-51)/二氧基二苯基砜(DDS)和E-51体系的固化动力学和热性能.结果表明:杂化树脂的固化反应活化能较大,POSS-NH2的加入提高了固化杂化树脂的热性能.     

巯基-苯基聚倍半硅氧烷对环氧树脂性能的影响

以巯丙基三甲氧基硅烷和苯基三甲氧基硅烷为原料,在酸性条件下水解缩合制备了巯基和苯基不同比例的巯基-苯基聚倍半硅氧烷,通过力学性能和涂膜性能测试,动态热力学分析及热重-示差扫描量热分析研究了其对环氧树脂E51性能的影响。结果表明:含巯基的聚倍半硅氧烷可作为环氧树脂的固化剂使用,且固化物涂膜性能和耐热性优异。加入质量分数20%的苯基单体合成的巯基-苯基聚倍半硅氧烷固化环氧树脂E51时,其热性能比单独的巯基聚倍半硅氧烷改性环氧树脂更为优异。     

环氧树脂/石英纤维透波复合材料制备

为改善环氧树脂的介电性能及提升石英纤维的界面性能,使用缩水甘油醚基笼型倍半硅氧烷(G-POSS)和γ-氨丙基三乙氧基硅烷(KH-550)分别对环氧树脂和石英纤维进行改性.利用差示扫描量热法研究改性后环氧树脂的固化过程,并通过外推法确定了其固化工艺,根据固化工艺制备环氧树脂/石英纤维复合材料,分别对该复合材料的热稳定性、...     

八（乙酰苯基）笼形倍半硅氧烷

西南科技大学的孟二辉等人以八苯基多面低聚倍半硅氧烷（OPS）为底物,无水三氯化铝为催化剂,经傅-克酰基化反应合成了笼形八（乙酰苯基）倍半硅氧烷（OAcPS）。较佳的合成条件为：二氯甲烷用量140mL,     

八（乙酰苯基）笼形倍半硅氧烷

西南科技大学的孟二辉等人以八苯基多面低聚倍半硅氧烷（OPS）为底物，无水三氯化铝为催化剂，经傅-克酰基化反应合成了笼形八（乙酰苯基）倍半硅氧烷（OAcPS）。较佳的合成条件为：二氯甲烷用量140mL，     

新型含磷阻燃剂的制备及在环氧树脂体系中的应用

本文以三氯氧磷、对羟基苯甲醛及DOPO为原料成功合成了一种新型含磷阻燃剂DOPO-TPPO,采用FTIR测试对其结构进行了表征。通过热重分析测试(TGA)研究了产物的热稳定性、热降解行为及成炭性能,表明该阻燃剂具有较好的热稳定性和成炭性能。将阻燃剂DOPO-TPPO添加到环氧树脂中,以二氨基二苯硫砜(DDS)为固化剂制备阻燃环氧树脂固化物,通过极限氧指数(LOI)和垂直燃烧(UL-94)测试研究了环氧树脂固化物的阻燃性能。结果表明:合成产物的起始热分解温度为195℃,在700℃时的残炭量为29%,当阻燃剂添加量(质量分数)为11.0%时,环氧树脂固化物能通过垂直燃烧UL-94 V-0级,氧指数高达32.0%,表明该物质对环氧树脂材料具有优异的阻燃性能。     

八(乙酰苯基)笼形倍半硅氧烷的合成及表征

以八苯基多面低聚倍半硅氧烷(OPS)为底物,无水三氯化铝为催化剂,经傅-克酰基化反应合成了笼形八(乙酰苯基)倍半硅氧烷(OAcPS)。用红外光谱、1H、13C、29Si核磁共振、元素分析、热分析等手段,对其结构和性质进行了表征。研究并讨论了溶剂用量和投料比对反应收率的影响。较佳的合成条件为:二氯甲烷用量140mL,n(acetyl chloride)∶n(OPS)=10∶1,n(AlCl3)∶n(OPS)=2.5∶1,在0℃反应6 h,产率达70%。     

笼型环氧GM-POSS改性双酚-A环氧树脂的固化动力学与热性能

为降低笼型倍半硅氧烷环氧树脂的官能度,合成了一种含有部分甲基的笼型倍半硅氧烷环氧树脂(GM-POSS),其结构以六面体的T8结构为主.用DSC、TG、TBA和x-射线能谱仪研究了GM-POSS/双酚-A环氧共混物与甲基四氢苯酐(MeTHPA)的固化性能及热性能.结果表明2种环氧可共同固化,固化反应的平均活化能Ea为71.10 kJ/mol,反应级数为一级;固化树脂的玻璃化转变温度、热分解温度及热残余量均随GM-POSS加入量的增加而升高.     

Thermal and dielectric properties and curing kinetics of nanomaterials formed from poss-epoxy and meta-phenylenediamine

A nanoporous polyhedral oligomeric silisesquioxane (POSS) containing eight epoxy functional groups [octakis(dimethylsiloxypropylglycidyl ether)silsesquioxane, OG] reacts with meta-phenylenediamine (mPDA) to form epoxy resin network with nanostructures. The glass transition temperature (T_g) of the cured OG/mPDA product is significantly higher than that of the diglycidyl ether of bisphenol A (DGEBA) cured with mPDA (DGEBA/mPDA) material due to the presence of the POSS cages that is able to effectively hinder the motion of the network junctions. The cured OG/mPDA product inherently possesses higher thermal stability than the cured DGEBA/mPDA product based on higher maximum decomposition rate temperature, and higher char yield of the former. However, the existence of large fraction of the unreacted amine groups causes lower initial decomposition temperature of the OG/mPDA because it tends to decompose or volatilize on heating at relatively low temperature. The dielectric constant of the OG/mPDA material (2.31) is substantially lower than that of the DGEBA/mPDA (3.51) as a consequence the presence of nanoporous POSS cubes in the epoxy matrix.     

环氧树脂/POSS杂化材料力学性能和耐热性研究

以自行合成的环氧基倍半硅氧烷（POSS）为改性剂,分别对环氧树脂139S/六氢苯酐和环氧树脂BE 188EL/六氢苯酐进行改性,制备环氧树脂/POSS杂化材料。力学性能分析结果表明,两种杂化材料的冲击强度和弯曲强度都有明显的提高,冲击强度分别提高了57.45 %和32.26 %,弯曲强度分别提高了9.23 %和5.07 %。热性能分析结果表明,两种杂化材料在高温时的热残留量都有所提高,分别提高了50.19 %和20.16 %。两种杂化材料的热膨胀系数也得到了降低,即热稳定性得到了提高。     

Allylated novolac/4,4′‐bismaleimidodiphenylmethane resin containing polyhedral oligomeric silsesquioxane: Preparation,morphology and thermal stability

Allylated novolac/4,4′‐bismaleimidodiphenylmethane resin (AN/BDM) had been modified with well‐defined inorganic building blocks‐polyhedral oligomeric silsesquioxane (POSS). Octamaleimidophenyl polyhedral silsesquioxane (OMPS) was used as the cocuring reagent of the AN/BDM resin to prepare POSS‐modified AN/BDM resin, and POSS content was between 0 and 17.8 wt %. The curing reaction of the POSS‐modified AN/BDM resin was monitored by means of Fourier transform infrared spectroscopy (FTIR), and the results revealed that maleimide groups on OMPS molecule could undergothe curing reaction between allyl groups and maleimide groups. Therefore, the crosslinked network containing POSS was formed. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were employed to study the morphology of the cured POSS‐modified AN/BDM resins. The homogeneous dispersion of POSS cages in AN/BDM matrices was evidenced. Thermogravimetric analysis (TGA) indicated that incorporation of POSS into AN/BDM crosslinked network led to enhanced thermal stability. The improved thermal stability could be ascribed to higher crosslink density and inorganic nature of POSS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3903–3908, 2007     

Epoxidized pine oil‐siloxane: Crosslinking kinetic study and thermomechanical properties

In this study, a novel approach to toughen biobased epoxy polymer with different types of siloxanes was explored. Three different modified siloxanes, e.g., amine‐terminated polydimethyl siloxane (PDMS‐amine), glycidyl‐terminated polydimethyl siloxane (PDMS‐glycidyl), and glycidyl‐terminated polyhedral oligomeric silsesquioxane (POSS‐glycidyl) were used as toughening agents. The curing and kinetics of bioepoxy was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. The mechanical, thermal, and morphological properties of the cured materials were investigated. Rheological characterization revealed that the inclusion of POSS‐glycidyl slightly increased the complex viscosity compared to the neat resin. The morphology of the cured bioresin was characterized by transmission electron microscopy and scanning electron microscopy. The inclusion of POSS‐glycidyl to bioepoxy resin resulted in a good homogeneity within the blends. The inclusion of PDMS‐amine or PDMS‐glycidyl was shown to have no effect on tensile and flexural properties of the bioresins, but led to a deterioration in the impact strength. However, the inclusion of POSS‐glycidyl enhanced the impact strength and elongation at break of the bioresins. Dynamic mechanical analysis showed that the siloxane modified epoxy decreased the storage modulus of the bioresins. The thermal properties, such as decomposition temperature, coefficient of linear thermal expansion, and heat deflection temperature were improved by inclusion of POSS‐glycidyl. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42451.     

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     

Dimethacrylic/epoxy interpenetrating polymer networks including octafunctional POSS

This investigation presents the synthesis of simultaneous interpenetrating polymer networks based on dimethacrylic/epoxy resins with or without polyhedral oligomeric silsesquioxane (POSS) via in situ polymerization. The curing behavior was studied using differential scanning calorimetry (DSC). The influence of the organic groups from the POSS cages on the curing kinetics of the IPNs was also studied by FT-IR spectrometry. The homogeneous phase structure of the cured IPN was proved by DMA tests. Additionally the integrity of the IPN was also demonstrated by thermal decomposition which occurs in one single step.     

Synthesis and characterization of vinyl‐polyhedral oligomeric silsesquioxanes‐reinforced silicone resin with three‐dimensional cross‐linking structure

A novel thermal stability and highly transparent silicone resin‐type material was prepared via hydrosilylation of vinyl‐polyhedral oligomeric silsesquioxanes (POSS)‐grafted methylhydrosilicone oil and vinylmethylsilicone oil in the presence of Karstedt catalyst. The morphology, mechanical property, thermal stability, optical transmittance, thermal‐oxidation resistance of the vinyl‐POSS‐reinforced silicone resins were systematically investigated. Scanning electron microscopy showed that the vinyl‐POSS‐reinforced silicone resins had good compatibility with polydimethylsiloxane (PDMS) systems. The mechanical analysis and thermo gravimetric analysis indicated that the mechanical properties and thermal stability increased with increasing quantity of vinyl‐POSS. However, the optical transmittance increased with the increasing amount of vinyl‐POSS rather than decreased. In addition, the incorporation of vinyl‐POSS did not improve the thermal resistance of the PDMS polymers. The product has the potential application for LED packaging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42187.     

Phenolic resin-trisilanolphenyl polyhedral oligomeric silsesquioxane (POSS) hybrid nanocomposites: Structure and properties

The structure and properties of organic-inorganic hybrid nanocomposites prepared from a resole phenolic resin and a POSS mixture containing >95 wt% trisilanolphenyl POSS was investigated by POM (polarized optical microscopy), SEM, TEM, WAXD, FT-IR, DSC, and TGA techniques. Composites with 1.0-10.4 wt% of POSS were prepared by dissolving the POSS and the phenolic resin into THF, followed by solvent removal and curing. Both nano- and micro-sized POSS filler aggregates and particles were shown to be heterogeneously dispersed in the cured matrix by POM, TEM, SEM, and X-EDS. POSS was found everywhere, including in both dispersed phase domains and in the matrix. The nanocomposite morphology appears to form by a multi-step POSS aggregation during the process of phase separation. Both the matrix and dispersed ‘particulate’ phase domains are mixtures of phenolic resin and POSS. POSS micro-crystals act as the core of the dispersed phase. The bigger dispersed domains consist of smaller particles or aggregates of POSS molecules that exhibit some order but regions of matrix resin are interspersed. A WAXD peak at 2θ∼7.3° indicates crystalline order in the POSS aggregates. This characteristic peak's intensity increases with an increase in POSS loading, suggesting that more POSS molecules have aggregated or crystallized. FT-IR spectra confirm that hydrogen bonding exists between the phenolic resin and POSS Si-OH groups. This increases their mutual compatibility, but H-bonding does not prevent POSS aggregation and phase separation during curing. TGA measurements in air confirmed the temperature for 5% mass loss in increases with increase of POSS loading and at T>550° the thermal stability increases more sharply with POSS loading. The nanocomposite glass transition temperatures (T_g) are only slightly be affected by the POSS filler.     

Formation of nanostructured epoxy networks containing polyhedral oligomeric silsesquioxane (POSS) blocks

Nanostructured epoxy networks, based on DGEBA and poly(oxypropylene)diamine (Jeffamine D), containing nano-sized inorganic blocks, polyhedral oligomeric silsesquioxanes (POSS), were investigated. The POSS were incorporated in the network as crosslinks or as pendant units by using octa- or monoepoxy-POSS monomers, respectively, as well as diepoxides with pendant POSS. The authors focused on investigating the relationship between the network formation process and the final product properties. The reactivity of the epoxy-functional POSS monomers, the hybrid systems' time of gelation, the gel fractions and the phase structure of the networks were determined using ¹H or ¹³C NMR spectroscopy, chemorheology experiments, sol-gel analysis and transmission electron microscopy (TEM).All the POSS epoxides tested show a reduced reactivity if compared to their respective model compounds due to sterical crowding in the neighborhood of their functional groups and due to reduced epoxy group mobility. The incorporation of pendant POSS into networks of the type DGEBA-Jeffamine D-monoepoxy-POSS hence took place only in the late reaction stage. Together with the high tendency of these POSS to aggregation, the kinetics favors the formation of small nano-phase-separated POSS domains, which act as physical crosslinks due to their covalent bonds to the organic matrix. At POSS loadings higher than 70%, topological constraint by POSS leads to a strongly reduced elastic chain mobility, thus additionally strongly reinforcing the networks. The network build-up and gelation of the octaepoxy-POSS-Jeffamine D system were slow compared to the reference DGEBA-Jeffamine D network due to a low octaepoxy-POSS reactivity and due to its strong tendency to cyclization reactions with primary amines. The topology of the amino groups is shown to be very important. In contrast to monoepoxy-POSS, the octaepoxy-POSS becomes dispersed as oligomeric junctions (purely chemical crosslinks) of the network in the cured product. The octaepoxide's reinforcing effect is small and is given only by its high functionality and not by its inorganic nature. The functionality effect is reduced by the mentioned cyclizations.     

POSS/PS复合材料的制备及其热性能研究

以1,3,5,7,9,11,13-苯基-15-氯丙基笼型倍半硅氧烷(POSS-Cl)与二乙醇胺进行反应,将末端氯基团转化为两个端羟基,通过羟基与2-溴代异丁酰溴的酯化反应得到POSS-(Br)2引发剂,并运用原子转移自由基聚合(ATRP)成功合成了一种新型POSS/PS复合材料。采用傅里叶红外(FTIR)、核磁共振(NMR)等手段对POSS和POSS/PS的结构进行了表征。通过差示扫描量热(DSC)和热失重(TGA)分析对POSS/PS复合材料的热性能进行了研究。结果表明:POSS单元的引入能显著提高聚合物的热稳定性。