POSS/PMMA纳米复合材料的制备及性能研究

采用八乙烯基倍半硅氧烷(OV-POSS)通过原位聚合法制备了具有交联网状结构的POSS/PMMA纳米复合材料。通过FT-IR、DSC等方法对纳米复合材料的结构和性能进行了表征。结果表明,通过原位聚合法制备的POSS/PMMA纳米复合材料具有交联网状结构,POSS的引入能明显改善材料介电性能和热学性能,但当OV-POSS含量较高时,热学性能有所下降。当POSS的用量为0.6%时,POSS/PMMA纳米复合材料的介电常数从2.91降低至2.77,介电损耗从0.0088降低至0.0039,复合材料的Tg也上升了。     

Novel hybrid polyurethane/POSS materials via bulk polymerization

Novel polyurethane (PU)/polyhedral oligomeric silsesquioxane (POSS) hybrid elastomers were synthesised via reaction carried out in bulk. The isocyanate octasubstituted POSS (NCOPOSS) was used as the crosslinking agent for the polyurethane systems, which were similar to those commercially available for the production of urethane elastic materials (in contrast to model systems previously reported in literature). The structure and amorphous morphology of the resulting elastomers were confirmed by FTIR ATR spectroscopy and WAXS measurements, respectively. The elastomers were characterized by their mechanical (tensile, hardness) and thermal (T_g, thermal stability) properties. It was found that the incorporation of small amount (1.2–2.5 wt.%) of the NCOPOSS into the formulation resulted in an improvement or deterioration in mechanical properties of the polymer, depending on the diisocyanate used. Further increase in the NCOPOSS concentration resulted only in a loss of mechanical properties. A possible explanation is an over-crosslinking or wastage of POSS-deriving NCO groups (which did not react earlier with bulky polyols) in the reaction with the chain extender leading to cycle formation. Incorporation of the NCOPOSS into the PU elastomer reduced somewhat thermal stability of the latter probably due to the poor thermal stability of the NCOPOSS itself.     

交联网状结构POSS/PMMA纳米复合材料的研究

采用八甲基丙烯酰氧丙基POSS通过原位聚合法制备了交联网状结构的POSS/PMMA纳米复合材料,并采用FT-IR、XPS、SEM、TG、DSC等方法对其结构和性能进行表征。结果表明,POSS/PMMA纳米复合材料具有交联网状结构;POSS的加入对PMMA可见光的透过性无影响;当POSS的摩尔分数为0.6%时,相对于PMMA,复2合材料的拉伸强度和模量分别提高了24.7MPa和0.89GPa,冲击强度提高了6.2kJ/m,弯曲强度和模量分别提高了19.7MPa和1.71GPa,断裂伸长率略有降低。复合材料的热稳定性和T有所提高,但初始分解温度略有下降。g     

POSS Core star‐shape molecular hybrid materials: Effect of the chain length and POSS content on dielectric properties

A series of inorganic–organic molecular hybrids, poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane)s (PS‐POSSs), were synthesized, and their structures and properties were characterized by FTIR, ¹H‐NMR, ²⁹Si‐NMR, XRD, optical microscopy (OM), and atomic force microscopy (AFM). The chemical incorporation of POSS into polymer matrixes achieves uniform dispersion and makes the resultant hybrids display good film formability. The relationship between molecular structure of these hybrids and their dielectric constants and formation mechanism of low dielectric constant were investigated. The low dielectric constant of the hybrids mainly originates from the increase of free volume, involving the free volume of intrinsic porosity from POSS and an increase in the free volume owing to steric hindrance of bulky POSS. The latter plays a dominant role to increase the free volume and formation of low dielectric constant. Simultaneously, the polymer arm‐length has an important influence on the dielectric constant of the star‐type hybrids. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

硅烷偶联剂对聚甲基丙烯酸甲酯/二氧化硅纳米复合材料结构与性能的影响

采用乙烯基三乙氧基硅烷(WD-20)作为偶联剂,通过溶胶-凝胶法合成了聚甲基丙烯酸甲酯(PMMA)/二氧化硅(SiO₂)纳米复合材料,采用紫外-可见光谱、红外光谱、扫描电子显微镜和热机械分析等研究了材料的结构和性能.结果表明,WD-20的加入对纳米复合材料透明性、耐热性能和微观形态结构有较大影响,随着WD-20用量的增加,纳米复合材料透明性增加,SiO₂分散相尺寸变小,玻璃化转变温度增加.当WD-20与四乙基原硅酸盐（TEOS）之比为0.2时,所制备的纳米复合材料的溶胶分数为6%、玻璃化转变温度为250 ℃以上、可见光透过率在80％以上、SiO₂分散相尺寸小于100 nm.     

POSS/CE杂化复合材料的制备与介电性能研究

为制备介电常数(ε)低、介电损耗因子(tanδ)小的集成电路板用树脂基体,以笼型倍半硅氧烷(POSS)对双酚A型氰酸酯(CE)树脂进行改性,制备出一种POSS/CE无机-有机杂化复合材料。着重探讨了POSS用量和后处理工艺等对POSS/CE树脂体系介电性能的影响。结果表明:当w(POSS)=2%(相对于CE单体质量而言)、后处理工艺为240℃/3 h时,改性体系的介电性能相对最好,其测试频率为60 MHz时的ε(为2.9)和tanδ(为0.004 5)分别比纯CE树脂降低了9.4%和35.7%;该改性体系的表观活化能为51.9 kJ/mol。     

POSS/PMMA纳米复合材料的制备及性能

将笼形纳米粒子八己烯基多面低聚倍半硅氧烷(Oh-POSS)与聚甲基丙烯酸甲酯(PMMA)通过溶液共混法制备无机/有机纳米复合材料.利用FTIR对复合材料的结构进行表征.SEM观察结果显示:当Oh-POSS含量较小时,复合材料薄膜具有较为平整的表面,无机粒子Oh-POSS均匀地分散在PMMA基体之中;随着Oh-POSS含量的增加,Oh-POSS逐步发生聚集现象.TGA、DSC以及拉伸试验结果表明:Oh-POSS含量较低时,Oh-POSS的引入能明显改善材料的热稳定性和力学性能,但当Oh-POSS含量较高时,热学和力学性能下降.     

POSS/PMMA杂化材料的制备及性能研究

采用八乙烯基倍半硅氧烷（OV-POSS）通过原位聚合法制备了POSS/PMMA杂化材料。通过FTIR、SEM,EDS以及力学性能和透光性雾度的测定等方法对杂化材料的结构和性能进行了表征。结果表明,POSS的加入对PMMA可见光的透过性无影响。POSS含量较低时,POSS的引入能明显改善材料力学性能,但当POSS含量较高时,力学性能下降。当POSS的含量为0.6%时,与纯的PMMA相比,断裂伸长率略有降低,降低了5.8%,然而,其他力学性能均有提高,其中,拉伸模量和强度分别提高了22.7%和32.0%,弯曲强度和模量分别提高了9.8%和27.0%。     

Study of the effects of melt blending speed on the structure and properties of phosphate glass/polyamide 12 hybrid materials

The effects of melt blending conditions on the rheology, crystallization kinetics, and tensile properties of phosphate glass/polyamide 12 hybrid systems were investigated for the first time, to understand their complex processing/structure/property relationships. Increasing amounts of phosphate glass (Pglass) caused an increase in hybrid viscosity. Hybrid viscosity was also affected by processing (melt‐mixing) speed and small‐amplitude oscillatory shear tests and scanning electron microscopy (SEM) were used for a qualitative examination of the hybrid morphology. The addition of Pglass caused a decrease in hybrid crystallinity that was unaffected by processing (melt‐mixing) speed. The two‐parameter Avrami equation was applied successfully to the hybrid systems, and Pglass was found to nucleate the growth of polyamide 12 crystals. The nucleation effect was found to be dependent on concentration and processing history. The tensile properties of the hybrids were also studied, and the Halpin–Tsai equation was applied to the results to determine the maximum packing fraction of the Pglass. These results provide a basis for the prediction of hybrid mechanical properties for different Pglass concentrations and processing histories. Further, because of their facile processibility and desirable characteristics, such as the strong physicochemical interaction between the hybrid components and favorable viscoelasticity, these Pglass/polyamide 12 hybrids can be used as model systems for exploring feasibility of new routes for driving organic polymers and inorganic Pglass to self‐assemble into useful organic/inorganic hybrid materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Molecular dynamics simulation study on the structure and properties of polyimide/silica hybrid materials

A type of polyimide/silica (PI/SiO₂) copolymer model was established through the dehydration of tetraethyl orthosilicate molecules (TEOS) and bonding to a silane coupling agent. The content of SiO₂ was controlled by adjusting the number of molecules which bound to the TEOS. Finally, the silica was formed into a hybrid model (hybrid PI/SiO₂) with a small molecule embedded in the PI. The model was optimized by geometric and molecular dynamics and the changes in the model structure, Young's modulus, shear modulus, and glass-transition temperature (T _g) were analyzed. The results showed that the density and cohesive energy density of the composites could be improved by doping SiO₂ in PI. Young's modulus and shear modulus of PI/SiO₂ hybrid materials were higher than undoped PI. The tensile strength reached 568.15 MPa when the doping content was 9%. Therefore, the structure design and content control of SiO₂ was an effective way to improve the performance of a PI/SiO₂ composite. The variation of T _g and tensile strength of PI/SiO₂ hybrid composites is consistent with that of PI/SiO₂ composite synthesized in real experiment, which will be a convenient method for new material design and performance prediction. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47335.     

The influence of POSS substituent on synthesis and properties of hybrid materials based on urethane dimethacrylate (UDMA) and various polyhedral oligomeric silsesquioxane (POSS)

DSC was used to follow the degree of conversion (DC) for the methacrylic groups in the case of some hybrid systems based on urethane dimethacrylate (UDMA) monomer and various polyhedral oligomeric silsesquioxane (POSS) structures (HISO‐POSS, CPENTYL‐POSS, and MA‐POSS). The chemical structure of the POSS compound directly influences the DC value. The conversion of the methacrylic groups from the hybrid composites after thermal curing was determined by measuring the residual heat of reaction. Both SEM and AFM techniques were additionally used to performed an advanced morphological characterization for the obtained POSS‐nanocomposites. The DSC data have been corroborated with those resulted from the NIR spectroscopy. The introduction of POSS compound within the UDMA matrix leads to a decrease of the hybrid material transparency due to the formation of agglomerates also pointed out by SEM analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

紫外光固化块体PMMA/SiO2有机/无机杂化材料

以正硅酸乙酯（TEOS）、甲基丙烯酸甲酯（MMA）为原料,采用溶胶－凝胶法和紫外光固化技术制备块体PMMA/SiO2有机/无机杂化材料,通过透射电镜（TEM）、红外光谱（FTIR）和差热分析（DSC）研究了杂化材料的微观特性和热性能,研究表明该方法制备的二氧化硅溶胶粒径在100 nm左右,分散良好;杂化材料中有机相和无机相是以共价键的形式相互连接的,没有出现有机相和无机相的相分离现象,并且两相之间形成了互穿的网络结构。     

竹纤维/SiO_2杂化材料的制备、结构与性能

以竹纤维为原料,正硅酸乙酯(TEOS)为无机前驱体,使用溶胶-凝胶法制备竹纤维/Si O2杂化材料。通过X-射线衍射分析(XRD)、红外分析(FTIR)、扫描电镜分析(SEM)和热重分析(TG)研究了杂化材料的结构特征和热性能。结果表明,竹纤维的空隙被TEOS自身水解缩合生成的Si O2凝胶粒子填充,竹纤维素中的羟基与TEOS水解产生的羟基发生缩合反应,生成Si—O—C键,形成无机/生物质杂化材料。竹纤维/Si O2杂化材料的热稳定性要好。竹纤维/Si O2杂化材料的热解起始温度为298.2℃,1 000℃时的残余物约为总重的50%。     

竹纤维/SiO_2杂化材料的制备、结构与性能

以竹纤维为原料,正硅酸乙酯(TEOS)为无机前驱体,使用溶胶-凝胶法制备竹纤维/Si O2杂化材料。通过X-射线衍射分析(XRD)、红外分析(FTIR)、扫描电镜分析(SEM)和热重分析(TG)研究了杂化材料的结构特征和热性能。结果表明,竹纤维的空隙被TEOS自身水解缩合生成的Si O2凝胶粒子填充,竹纤维素中的羟基与TEOS水解产生的羟基发生缩合反应,生成Si—O—C键,形成无机/生物质杂化材料。竹纤维/Si O2杂化材料的热稳定性要好。竹纤维/Si O2杂化材料的热解起始温度为298.2℃,1 000℃时的残余物约为总重的50%。     

Preparation of VB‐a/POSS hybrid monomer and its polymerization of polybenzoxazine/POSS hybrid nanocomposites

A benzoxazine monomer (VB‐a) containing an allyl groups was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine (bisphenol‐A and allylamine as VB‐a). This monomer was then reacted with polyhedral oligomeric silsesquioxane (POSS) through hydrosilylation, followed by thermal curing to form poly(VB‐a)/POSS hybrid nanocomposites. The curing behavior of the nanocomposites was monitored using Fourier transform infrared spectroscopy (FTIR), and their thermal and morphological properties were investigated through thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and scanning electron microscopy. DMA revealed that the glass transition temperatures of the poly(VB‐a)/POSS nanocomposites were higher than that of the pristine poly(VB‐a), presumably because the POSS cages effectively hindered the motion of the polymer chains. TGA confirmed that the thermal degradation temperatures and char yields of the polybenzoxazines increased after incorporation of the POSS moieties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

介孔SBA-15有机化修饰对PMMA杂化材料力学性能的影响

采用硅烷偶联剂对SBA-15进行了有机化修饰(即:SBA-15-G),利用在位分散聚合法制备了SBA-15/PMMA和SBA-15-G/PMMA杂化材料,研究了SBA-15和SBA-15-G在PMMA基体中的介观有序性和分散性以及对杂化材料的力学性能的影响规律。结果表明有机化修饰使SBA-15孔容、孔径和比表面积减小,表面亲油性提高;SBA-15和SBA-15-G在基体中仍保持长程有序结构;有机化修饰改善了SBA-15在基体中的分散性和与基体的界面结合,显著增强了杂化材料的力学性能。当SBA-15-G为4%时,杂化材料的拉伸强度和模量分别提高了45%和40.4%,当SBA-15-G为2%时冲击强度达到最大,比基体提高了36.6%。,     

Trisilanolisobutyl POSS/polyurethane hybrid composites: preparation,WAXS and thermal properties

Trisilanolisobutyl polyhedral oligomeric silsesquioxane (TSI-POSS) with three hydroxyl functional groups pendent to an open cage, was incorporated in concentrations of 7, 13 and 22 wt% into 4,4′-methylenebis(phenyl isocyanate) and glycerol propoxylate to prepare TSI-POSS–PU hybrid composites as a heavy linking node in polymer backbone, respectively. These composites were characterized by FTIR, wide-angle X-ray scattering (WAXS), dynamic mechanical analysis and thermogravimetry techniques. In WAXS profiles, above 22 wt% TSI-POSS concentration, the morphology of composite is significantly altered and distinct crystallite clusters are formed, which increase the volume of hard segment in polyurethane (PU) hybrid composite. As TSI-POSS concentration rises, the glass transition temperature (T _g) of composites is increased while the decomposition temperature is slightly decreased due to the oxysensitive isobutyl groups in structure. Meanwhile, the activation energy of hybrid composites is nearly unchanged indicating that the formation of crystallite cluster, which restricts motion of surrounding chains, is the predominant effect in T _g increasing. It can be concluded that the morphology and the thermal property of polyurethane can be tailored by TSI-POSS incorporation, whereas functional group in TSI-POSS structure is the decisive factor for the thermostability of designed composites.     

Influence of polyhedral oligomeric silsesquioxanes on thermal and mechanical properties of polycarbonate/POSS hybrid composites

Two types of silsesquioxanes were synthesized by hydrolytic condensation reaction, and then were incorporated into polycarbonate (PC) matrix by melt blending to prepare PC/POSS hybrid composites. The study of morphology of the composites showed that octaphenylsilsesquioxane (PH‐POSS) exhibited partial compatibility with PC matrix, while 3‐glycidyloxypropylsilsesquioxane (EP‐POSS) could react with phenolic hydroxyl groups of matrix. Thermal and mechanical properties were studied by DSC, TGA, and DMA. The result showed that the incorporation of POSS not only improved thermal stabilities of PC composites, but also retarded their thermal degradation. Si O fractions left during POSS degradations were the key factor governing the formation of a gel network layer on the exterior surface. This layer possessed more compact structures, higher thermal stabilities, and some thermal insulation. In addition, percentage residues at 700°C (C₇₀₀) significantly increased from 10.8 to 15.5–22.8% in air. The storage modulus of two series of composites was slightly improved up to 90°C; furthermore, the temperature range of the rubbery state of them shifted to high temperature. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Preparation and characterization of polyurethane/POSS hybrid aqueous dispersions from mono-amino substituted POSS

A series of linear polyurethane (PU) aqueous dispersions modified by polyhedral oligomeric silsesquioxane (POSS) was synthesized by incorporating various amounts (ca. 2–10 wt%) of a secondary amino-terminated monofunctional POSS in hexamethylene diisocyanate trimer (HDI-T), hexamethylene diisocyanate, poly(tetramethylene-oxide) and 2,2-bis(hydroxymethyl)propionic acid. Results from the gel permeation chromatography, Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction showed that the POSS monomers could be effectively introduced into the PU matrices based on HDI-T to obtain stable aqueous and homogenous PU/POSS hybrid dispersions. The thermal properties of the hybrids do not significantly affect the degradation mechanism of the PU. The physical properties of the PU/POSS hybrid films changed, with a notable increase in tensile strength and surface hydrophobicity.     

Segmental dynamics in hybrid polymer/POSS nanomaterials

Of the many nanomaterials available today, polyhedral oligomeric silsesquioxanes (POSS) are in a class of their own as they hold the capability to combine unique reactive inorganic–organic hybrid chemical compositions with nano-sized dimensionally stable cage structures. Depending on the structure and reactivity of their vertex groups, POSS may be blended in a polymer matrix, grafted as side chains, lie on the main macromolecular contour or even act as large, multifunctional chemical crosslinks. POSS is known to influence polymer segmental dynamics with several accelerating or decelerating mechanisms, that often lead to a significant decrease or increase of the glass transition temperature (T_g), respectively. This review explores these mechanisms with respect to the chemical nature of the organic substituents and the resulting particle–polymer interactions; the synthesis route, the chain topology, and the degree of dispersion. T_g vs content data are compiled from the primary literature in a series of comparative graphs. It will be shown that the dependence of T_g on the composition of the POSS nanomaterials can be often discussed and considered in terms similar to those used for polymer blends and copolymers.