一种星形大分子引发剂的合成与表征

本文以笼形八聚(二甲基硅烷基)倍半硅氧烷(Q8M8H)?烯丙醇??-溴代异丁酰溴为原料通过氢化硅烷化反应和酯化反应合成了八聚(2-溴-2-甲基异丁基硅氧基)倍半硅氧烷(OBPS)星形大分子引发剂,并通过FTIR、1H-NMR、29Si-NMR和GPC对其结构进行了表征,讨论了溶剂?温度和时间对产物结构和产率的影响?最佳反应条件为:以THF为溶剂,0℃反应3h,室温下反应20h,产率可达85.0%?该化合物可进一步做为原子转移自由基聚合的引发剂制备星形聚合物?     

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.     

星型聚合物中间体环硅氧烷核的合成研究

以甲基二氯硅烷、四甲基四乙烯基环四硅氧烷(DVi4)为原料,采用硅氢加成反应合成了星型聚合物的中问体环硅氧烷核,并用红外光谱和核磁共振谱进行了表征.反应的最佳条件是:采用预先活化、反应温度72℃、催化荆与DVi4的量之比为1.0×10-4,反应转化率可达95%,且选择性很好,产物主要为β-加成产物.     

POSS/聚合物复合材料的研究进展

介绍了POSS/聚合物复合材料的基本特性,以及常见的几种制备方法 (物理共混法和化学共聚法),指出了POSS/聚合物复合材料相对于常规纳米高分子复合材料在性能上的差异。对POSS/聚合物复合材料在发展过程中存在的一些问题进行了分析并展望了发展趋势。     

树枝状-星型聚合物的合成研究进展

介绍了树枝状-星型聚合物的合成方法,重点综述了以树枝状大分子引发剂合成树枝状-星型聚合物的研究进展,对树枝状-星型聚合物的性质和应用等进行了讨论.     

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。     

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。     

元素有机聚合物及其涂料

用于高温环境下的有机硅垫圈涂料组合物,多面体低聚体倍半硅氧烷及作为涂料、复合物和助剂的金属化多面体低聚倍半硅氧烷,含甲硅烷基的聚乙烯醇防雾剂及其涂覆的透明件,基于聚硅氮烷的亲水涂料,     

一种耐高温聚硫代醚高分子的合成及其应用

利用巯基化合物与含烯基化合物的自由基反应合成了一种含有多面体低聚倍半硅氧烷(Polyhedral Oligomeric Silsesquioxane,简称POSS)结构的聚硫代醚高分子,并研究了这种高分子的热力学性质。使用这种聚硫代醚高分子为生胶通过二氧化锰硫化制备了一种聚硫代醚密封剂,研究了它的机械性能以及抗热空气老化性能。     

POSS/聚合物有机-无机杂化材料的研究进展

介绍了笼型倍半硅氧烷(POSS)的特点。综述了POSS/聚合物杂化材料近年来的研究进展(包括POSS/环氧树脂杂化材料、POSS/聚酰亚胺杂化材料、POSS/有机硅杂化材料、POSS/聚乙烯杂化材料、POSS/聚丙烯杂化材料和其他类型含POSS的杂化材料等),并对其应用前景进行了展望。     

Synthesis and characterization of polyimide/polyhedral oligomeric silsesquioxane nanocomposites containing quinolyl moiety

A series of functional polyhedral oligomeric silsesquioxane (POSS)/polyimide (PI) nanocomposites were prepared using a two‐step approach. First, octa(aminophenyl)silsesquioxane (OAPS) was mixed with poly(amic acid) (PAA) prepared by reacting bis(4‐amino‐3,5‐dimethylphenyl)‐3‐quinolylmethane and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. Second, the resulting solution was subjected to thermal imidization. The well‐defined ‘hard particles’ (POSS) and the strong covalent bonds in the amide linkage between the carbon atom of the carboxyl side group in PAA and the nitrogen atom of the amino group in POSS lead to a significant improvement in the thermal and mechanical properties. Homogeneous dispersion of POSS cages in the PI is evident from scanning electron microscopy, which further confirms that the POSS molecule becomes an integral part of the organic‐inorganic inter‐crosslinked network system. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the POSS‐containing nanocomposites are higher than that of the corresponding neat PI system, owing to the significant increase of the crosslinking density in the PI/POSS nanocomposites. Increasing the concentration of OAPS in the PI networks decreases the dielectric constant. Pure PI and PI/POSS systems have good antimicrobial activity. Copyright © 2011 Society of Chemical Industry     

Epoxy‐functionalized polyhedral oligomeric silsesquioxane/cyanate ester resin organic–inorganic hybrids with enhanced mechanical and thermal properties

A series of cyanate ester resin (CE) based organic–inorganic hybrids containing different contents (0, 5, 10, 15 and 20 wt%) of epoxy‐functionalized polyhedral oligomeric silsesquioxane (POSS‐Ep) were prepared by casting and curing. The hybrid resin systems were studied by the gel time test to evaluate the effect of POSS‐Ep on the curing reactivity of CE. The impact and flexural strengths of the hybrids were investigated. The micromorphological, dynamic mechanical and thermal properties of the hybrids were studied by SEM, dynamic mechanical analysis (DMA) and TGA, respectively. Results showed that POSS‐Ep prolonged the gel time of CE. CE10 containing 10 wt% POSS‐Ep displayed not only the optimum impact strength but the optimum flexural strength. SEM results revealed that the improvement of mechanical properties was attributed to the large amount of tough whirls and fiber‐like pull‐outs observed on the fracture surfaces of CE10. DMA results indicated that POSS‐CE tended to decrease E′ of the hybrids in the glassy state but to increase E′ of the hybrids in the rubbery state. TGA results showed that CE10 also possesses the best thermal stability. The initial temperature of decomposition (T_i) of CE10 is 426 °C, 44 °C higher than that of pristine CE. © 2013 Society of Chemical Industry     

甲基笼型倍半硅氧烷/CE杂化复合材料的力学性能

以甲基笼型倍半硅氧烷(POSS)作为氰酸酯树脂(CE)的改性剂,制备出一种POSS/CE杂化复合材料。研究了杂化复合材料中POSS用量对CE结构及力学性能的影响,同时采用红外光谱(FT-IR)法对不同POSS/CE体系的反应性进行了研究。结果表明:POSS的加入对CE的反应性影响不大,有利于POSS/CE杂化体系固化工艺的制定;当杂化体系中w(POSS)=5%时,材料的冲击强度(9.7 kJ/m2)相对最大(提高了49%),弯曲强度(90 MPa)也相对较高,说明适量的POSS对CE具有明显的增韧、增强作用。     

Star-shaped poly(?-caprolactone) with polyhedral oligomeric silsesquioxane core

A readily available octa(3-chloropropyl) polyhedral oligomeric silsesquioxane (POSS) [(ClCH₂CH₂CH₂)₈Si₈O₁₂] framework was used to prepare octa(3-hydroxypropyl) POSS [(HOCH₂CH₂CH₂)₈Si₈O₁₂], which was further used as an initiator to synthesize star poly(?-caprolactone) with POSS core via ring-opening polymerization catalyzed by Stannous (II) octanoate [Sn(Oct)₂]. The organic-inorganic star PCLs were characterized by means of gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). The wide-angle X-ray diffraction (WAXRD) experiments indicate that the presence of POSS cores did not alter the crystal structure of PCL. The star PCLs exhibited enhanced melting temperatures in comparison with the linear counterpart. The isothermal crystallization kinetics shows that both the overall crystallization rate and the spherulitic growth rate of the star PCLs increased with increasing the concentration of POSS (or with decreasing the arm lengths of the stars). The fold surface free energy of the star PCLs decreased with increasing the concentration of POSS. These results could be interpreted based on the effect of the heterogeneous nucleation of POSS cores, which accelerates the process of crystallization.     

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.     

Synthesis and antimicrobial activity of quaternary ammonium-functionalized POSS (Q-POSS) and polysiloxane coatings containing Q-POSS

An array of quaternary ammonium-functionalized POSS (Q-POSS) compounds were synthesized and their antimicrobial properties toward the Gram-negative bacterium, Escherichia coli, and the Gram-positive bacterium, Staphylococcus aureus, determined in aqueous solution. Using Q-POSS compositions that exhibited broad spectrum antimicrobial activity in solution, the utility of the Q-POSS compounds as an antimicrobial additive for polysiloxane coatings was determined. The results of the investigation showed that Q-POSSs possessing a relatively low extent of quaternization and longer alkyl chain lengths provided the highest antimicrobial activity in solution. For polysiloxane coatings containing Q-POSS molecules as an antimicrobial additive, coating surface energy, surface morphology, and antimicrobial properties were found to be strongly dependent on Q-POSS composition. Coatings based on Q-POSSs possessing the lowest extent of quaternization displayed antimicrobial activity while analogous coatings produced using Q-POSSs possessing the highest extent of quaternization showed no antimicrobial activity. The lack of antimicrobial activity exhibited by coatings possessing Q-POSSs with a relatively high extent of quaternization was attributed to agglomeration of Q-POSS molecules through the formation of intermolecular interactions involving the quaternary ammonium moieties. Agglomeration would be expected to reduce diffusivity and inhibit interaction of the Q-POSS molecules with microbial cells.