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%.     

Synthesis and characterization of differently substituted phenyl hepta isobutyl‐polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

Variously substituted polyhedral oligomeric silsesquioxanes (POSSs)/polystyrene (PS) nanocomposites of general formula R₇R′(SiO_1.5)₈/PS (where R = isobutyl and R′ = 4‐methoxyphenyl, 4‐methylphenyl, 3,5‐dimethylphenyl, 4‐fluorophenyl, 2,4‐difluorophenyl, 4‐chlorophenyl) were prepared by in situ polymerization of styrene in the presence of 5% w/w of POSS. The actual filler concentration in the obtained nanocomposites was checked by ¹H NMR spectroscopy. Scanning electron microscopy and FTIR spectroscopy evidenced the presence of filler‐polymer interactions. Inherent viscosity (η_inh) determinations indicated that the average molar mass of polymer in halogenated derivatives was lower than neat PS, and were in agreement with calorimetric glass transition temperature (T_g) measurements. Finally, a comparative study concerning the thermal stability of synthesized nanocomposites was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres into a thermobalance, in the scanning mode, at 10°C min⁻¹, and the temperatures at 5% mass loss (T_5%), of various compounds were determined. The results were discussed and interpreted. POLYM. COMPOS., 35:151–157, 2014. © 2013 Society of Plastics Engineers     

Thermal study on phenyl,hepta isobutyl‐polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

A comparative study concerning the thermal stability of polystyrene (PS) and three polyhedral oligomeric silsesquioxane/polystyrene (POSS/PS) nanocomposites of formula R₇R′(SiO_1.5)₈/PS (where R = isobutyl and R′ = phenyl), at various (3, 5, and 10%) POSS concentration was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were synthesized by in situ polymerization of styrene in the presence of POSS and the experimental filler concentration in the obtained compounds, determined by ¹H NMR spectroscopy, was in all cases slightly higher than that in the reactant mixtures. Inherent viscosity (η_inh) determinations indicated that the average molar mass of polymer in the nanocomposites was practically the same than neat PS and were in agreement with calorimetric glass transition temperature (T_g) measurements. The temperature at 5% mass loss (T_5%) and the activation energy (E_a) of degradation process of synthesized nanocomposites were determined and compared with each other and with those of unfilled PS. On the basis of the results from thermal and IR spectroscopy characterizations, nanocomposite with 5% of molecular filler appears the most thermally stable. The results were also compared with literature data on similar PS‐based nanocomposites. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

Poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxane) hybrid nanocomposites: Preparation,thermal properties,and Tg improvement mechanism

A series of poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxanes) (PVP‐POSS) organic–inorganic hybrid nanocomposites containing different percentages of POSS were prepared via free radical polymerization and characterized by FTIR, high‐resolution ¹H‐NMR, solid‐state ²⁹Si‐NMR, GPC, DSC, and TGA. POSS contents in these nanocomposites can be effectively controlled by varying the POSS feed ratios which can be accurately quantified by FTIR curve calibration. On the basis of ²⁹Si‐NMR spectra, average numbers of reacted vinyl groups of each octavinyl‐POSS macromer are calculated to be 5–7, which depends on POSS feed ratios. Both GPC and DSC results indicate that these nanocomposites display network structure and the degree of crosslinking increases with the increase of the POSS content. The incorporation of POSS into PVP significantly improves their thermal properties (T_g and T_dec) primarily due to crosslinking structure and dipole–dipole interaction between POSS cores and PVP carbonyl groups. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of poly(methyl methacrylate) nanocomposites containing octavinyl polyhedral oligomeric silsesquioxane

A series of poly(methyl methacrylate) (PMMA) containing octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) nanocomposites were synthesized by solution polymerization. The products were characterized by FTIR, ¹H NMR, GPC, TEM, DSC and TGA. The actual contents of OV-POSS in the obtained products and the reaction degree of the vinyl groups in the POSS were calculated on the basis of FTIR, TGA and ¹H NMR data respectively. The DSC and TGA results indicate that the incorporation of POSS molecules could improve the thermal properties of PMMA nanocomposites significantly. The glass transition temperature (T_g) and thermal decomposition temperature (T_dec1) of the nanocomposite with 12.27 wt % of OV-POSS were increased by 23 °C and 93 °C correspondingly. In our experiment, the improved thermal properties were largely attributed to the nanoreinforcement effect of POSS cages and the formation of star-shaped structures with cubic silsesquioxane core.     

Preparation and thermal properties of hybrid nanocomposites of poly(methyl methacrylate)/octavinyl polyhedral oligomeric silsesquioxane blends

A series of poly(methyl methacrylate) (PMMA)/octavinyl polyhedral oligomeric silsesquioxane (POSS) blends were prepared by the solution‐blending method and characterized with Fourier transform infrared, X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry, and thermogravimetric analysis techniques. The glass‐transition temperature (T_g) of the PMMA–POSS blends showed a tendency of first increasing and then decreasing with an increase in the POSS content. The maximum T_g reached 137.2°C when 0.84 mol % POSS was blended into the hybrid system, which was 28.2°C higher than that of the mother PMMA. The X‐ray diffraction patterns, transmission electron microscopy micrographs, and Fourier transform infrared spectra were employed to investigate the structure–property relationship of these hybrid nanocomposites and the T_g enhancement mechanism. The results showed that at a relatively low POSS content, POSS as an inert diluent decreased the interaction between the dipolar carbonyl groups of the homopolymer molecular chains. However, a new stronger dipole–dipole interaction between the POSS and the carbonyl of PMMA species formed at the same time, and a hindrance effect of nanosize POSS on the motion of the PMMA molecular chain may have played the main role in the T_g increase of the hybrid nanocomposites. At relatively high POSS concentrations, the strong dipole–dipole interactions that formed between the POSS and carbonyl groups of the PMMA gradually decreased because of the strong aggregation of POSS. This may be the main reason for the resultant T_g decrease in these hybrid nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The synthesis and characterization of polystyrene/magnetic polyhedral oligomeric silsesquioxane (POSS) nanocomposites

Fc-CHCH-C₆H₆-(C₅H₉)₇Si₈O₁₂ (POSS1, Fc: ferrocene) which contain both metal and CC double bond was firstly synthesized by Wittig reaction. The chemical structure of POSS1 was characterized by FTIR, ¹H, ¹³C and ²⁹Si NMR, mass spectrometry and elemental analysis, and the magnetic property of POSS1 have also been studied. Polystyrene composites containing inorganic-organic hybrid polyhedral oligomeric silsesquioxane (POSS1) were prepared by bulk free radical polymerization. XRD and TEM studies indicate that POSS1 is completely dispersed at molecular level in PS matrix when 1 wt% POSS1 is introduced, while some POSS1-rich nanoparticals are present when content of POSS1 is beyond 3 wt%. GPC results show that molecular weight of the PS/POSS1 nanocomposites are increased with addition of POSS1. TGA and TMA data show the thermal stabilities of PS/POSS1 nanocomposites have been improved compared to neat PS. The PS/POSS1 nanocomposites also display higher glass transition temperatures (T_g) in comparison with neat PS. Viscoelastic properties of PS/POSS1 nanocomposites were investigated by DMTA. The results show the storage modulus (E′) values (temperature>T_g) and the loss factor peak values of the PS/POSS1 nanocomposites are higher than that of neat PS. Mechanical properties of the PS/POSS1 nanocomposites are improved compared to the neat PS.     

Synthesis of core-shell particles by batch emulsion polymerization of styrene and octavinyl polyhedral oligomeric silsesquioxane

A new composite OVPOSS-PS was prepared by batch emulsion polymerization initiated by potassium persulfate. The structure of OVPOSS-PS composite was well characterized by FTIR, ¹H NMR, ²⁹Si NMR and XRD. The results indicated that OVPOSS could be incorporated into the PS matrix by the polymerization. TEM image shown that the composite particles were in regular shape with a uniform size and have a core-shell structure. Results of XRD revealed that POSS was well dispersed in the composites. The thermal properties were investigated by DSC and TGA. The data indicated that the incorporation of POSS can apparently improve the thermal stability of PS.     

Dielectric properties and solubility of multilayer hyperbranched polyimide/polyhedral oligomeric silsesquioxane nanocomposites

Multilayer hyperbranched polyimide/polyhedral oligomeric silsesquioxane (POSS) nanocomposites were synthesized by the reaction of a bromide‐hyperbranched polyether/POSS and a main‐chain polyimide containing hydroxyl‐functional groups. The first layer was formed through the direct reactions of the main‐chain hydroxyl groups with monochloroisobutyl polyhedral oligomeric silsesquioxane (POSS–Cl). The second and third layers were prepared by the repeated reactions of bromine ether branches that incorporated POSS–Cl with 3,5‐dihydroxybenzyl alcohol. Regardless of the fixed amount of POSS, the higher layers yielded lower dielectric constants. Even when the amount of the POSS loading was reduced 4‐fold, the third layer still had the lowest dielectric constants. The lowest dielectric constant of 2.54 was found in the third layer of the hyperbranched polyimide/POSS nanocomposite because of the large free volume and loose polyimide structures. The densities of the hyperbranched polyimide/POSS nanocomposite corresponded to the dielectric constants. The lower the density was, the higher the free volume was and the lower the dielectric constant was. The experimental results indicated that the hyperbranched polyimide/POSS nanocomposite exhibited increased solubility in comparison with pure polyimide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Synthesis and properties of silicon‐containing arylacetylene resins with polyhedral oligomeric silsesquioxane

A series of silicon‐containing arylacetylene resins containing polyhedral oligomeric silsesquioxane (PS resins) were synthesized by the hydrosilylation reaction between poly(dimethylsilyleneethynylenephenyleneethynylene) (PMSEPE) and octakis(dimethylsiloxy)octasilsesquoixane ( ) in the presence of a platinum catalyst (Pt‐dvs). The chemical structures and properties of PS resins were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, rheological analysis, differential scanning calorimetry, dielectric measurement, thermogravimetric analysis, and scanning electron microscopy. The results show that PS resins can be crosslinked to form thermosets at temperatures less than 260°C. With the increment of , the dielectric constants of the thermosets gradually decrease from 2.91 to 2.73. The thermooxidative stabilities of PMSEPE thermosets are obviously improved with the incorporation of . POLYM. ENG. SCI., 55:316–321, 2015. © 2014 Society of Plastics Engineers     

Influence of symmetry/asymmetry of the nanoparticles structure on the thermal stability of polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

The thermal degradation of two polyhedral oligomeric silsesquioxane/polystyrene (POSS/PS) nanocomposites of formula R₈(SiO_1.5)₈ POSS/PS and R′₁R₇(SiO_1.5)₈ POSS/PS (where R′ = Phenyl and R = Cyclopentyl), at 5% of POSS concentration, was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Compounds were prepared by the polymerization of styrene in the presence of POSS. Degradations were carried out into a thermobalance, in the scanning mode, at various heating rates, and the obtained thermogravimetric (TG) curves were discussed and interpreted. The initial decomposition temperature (T_i), the temperature at 5% mass loss (T_5%), the glass transition temperature (T_g), and the activation energy (E_a) of degradation of nanocomposites were determined and compared with each other and with those of unfilled PS. The T_i, T_5%, and degradation E_a values of nanocomposites were higher than those of neat PS, thus indicating a better heat resistance and lower degradation rate, and then a better overall thermal stability. The use of POSS with a symmetric structure, in the synthesis of PS based nanocomposite, showed a decrease of T_g value not only in respect to asymmetric POSS/PS nanocomposite but also in respect to neat polymer, thus suggesting an influence of filler structure in the thermal properties of the materials. POLYM. COMPOS., 33:1903–1910, 2012. © 2012 Society of Plastics Engineers     

Preparation and thermal property of hybrid nanocomposites by free radical copolymerization of styrene with octavinyl polyhedral oligomeric silsesquioxane

The poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PS–POSS) organic–inorganic hybrid nanocomposites containing various percent of POSS were prepared via one‐step free radical polymerization and characterized by FTIR, high‐resolution ¹H NMR, ²⁹Si NMR, GPC, DSC, and TGA technologies. The POSS contents in these nanocomposites were determined using FTIR calibration curve. The result shows that the POSS contents in nanocomposites can be tailored by varying the POSS feed ratios. On the basis of the POSS contents in the nanocomposites and the ¹H NMR spectra, the number of reacted vinyl groups of each octavinyl‐POSS macromonomer were calculated to be 6–8. DSC and TGA measurements indicate that the incorporation of POSS into PS homopolymer can apparently improve the thermal properties of the polymeric materials. The dramatic T_g and T_dec increases are mainly due to the formation of star and low cross‐linking structure of the nanocomposites, where POSS cores behave as the joint points and hinder the motion and degradation of the polymeric chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Highly soluble polyamide–polyhedral oligomeric silsesquioxane hybrid nanocomposites: Synthesis and characterization

A method of preparing linear polyamide‐polyhedral oligomeric silsesquioxane (PA‐POSS) hybrid nanocomposites in a reactor using thionyl chloride/triethylamine (TEA) as the activating agent was investigated. Soluble polyamic acid (PAA) having carboxylic acid end groups were first synthesized by condensation reaction of 2,2‐ bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2‐bis[4‐(4‐aminophenoxy)phenyl]‐1,1,1,3,3,3‐hexafluoropropane, (6FODA). The PAA was acylated by SOCl₂/TEA and followed by the addition of different mole percentages of aminopropyl heptacyclopentyl POSS (AP‐POSS) and 3‐(trifluoromethyl) aniline to get the PA‐POSS hybrid nanocomposites. The chemical structure of PA‐POSS hybrid nanocomposites were investigated by ATR‐FTIR and NMR spectroscopic techniques. Thermal and morphological properties of PA‐POSS were influenced by changing the percentage of POSS and investigated by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Wide angle X‐ray diffraction and contact angle measurements. The PA‐POSS with hexafluoroisopropylidene and POSS groups have higher bulk density resulting in higher free volume and then increasing the solubility property. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Octa(aminophenyl) polyhedral oligomeric silsesquioxane/boron‐containing phenol–formaldehyde resin nanocomposites: Synthesis,cured, and thermal properties

Octa(aminophenyl) polyhedral oligomeric silsesquioxane (OAP‐POSS) and boron‐containing phenol‐formaldehyde resin (BPFR) were synthesized, respectively. The BPFR nanocomposites with different OAP‐POSS content (wt%) were prepared, and their properties were characterized. The results show that the thermal degradation process of this nanocomposites can be divided into three stages, and they are all following the first order mechanism. The residual ratio and thermal degradation activation energy E_a of 9 wt% OAP‐POSS/BPFR nanocomposites are both better than others and the E_a increase gradually in three stages, which is 93.3, 134.0, and 181.9 kJ mol⁻¹, respectively. Its residual ratio at 900°C is 36.48%. The mechanical loss peak temperature T_p is 228°C for 12 wt% OAP‐POSSS/BPFR nanocomposites, which is higher 48°C than pure BPFR. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

笼型聚倍半硅氧烷交联聚苯乙烯微球疏水性的研究

采用分散聚合法制备聚苯乙烯微球,以甲基丙烯酸为交联剂、过硫酸铵为引发剂,将聚倍半硅氧烷与聚苯乙烯微球进行交联,并对交联后的聚苯乙烯微球进行红外光谱表征和热重分析。探讨了聚合温度对聚苯乙烯微球粒径的影响,着重分析了影响微球疏水性能的聚乙烯和十二烷基硫酸钠的因素。研究结果表明:聚乙烯对交联微球的浸润接触角以及十二烷基硫酸钠对交联微球的吸湿率影响显著;当w(聚乙烯)=40%(相对聚苯乙烯总质量而言)时,接触角为最大值146°,疏水性能较佳;当w(十二烷基硫酸钠)=1.5%(相对于乳液总质量而言)时,吸湿率较低为7.3%。     

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.     

Synthesis,characterization and surface properties of star‐shaped polymeric surfactants with polyhedral oligomeric silsesquioxane core

Star‐shaped amphiphilic polymeric surfactants comprising a hydrophobic polyhedral oligomeric silsesquioxane (POSS) core and hydrophilic poly(ethylene glycol) (PEG) arms with various chain lengths are successfully synthesized using copper(I)‐catalysed azide–alkyne cycloaddition (CuAAC) click reaction. Their chemical structures and molecular characteristics are clearly confirmed using Fourier transform infrared and ¹H NMR spectroscopies and gel permeation chromatography, and no homopolymer is found after CuAAC click reaction. Aqueous solutions of these star‐shaped polymers have been investigated using atomic force and transmission electron microscopies and dynamic light scattering studies and it is found that they can self‐assemble into micelles. The sizes of the micelles can be adjusted by the length of the PEG arms, where longer chains not only lead to increased micelle sizes, but also reduce the contact angle values. Moreover, the melting points and root mean square roughness of the obtained star‐shaped polymers are slightly increased on increasing the chain length of the PEG arms. © 2017 Society of Chemical Industry     

Flame retardancy and thermal stability of polyhedral oligomeric silsesquioxane nanocomposites

The flame retardancy and thermal stability of polyhedral oligomeric silsesquioxane (POSS) nanocomposites are reviewed. Results are summarized and compared on the basis of structure–property relationships. Because of the variability of groups attached on POSS, they exhibit different performance in polymer nanocomposites: metal‐containing POSS show good catalytic charring ability; vinyl‐containing and phenyl‐containing POSS promote the strength of char. Improvements in the cone calorimeter (such as reduced peak heat release rate) are advantages of POSS as preceramics for fire retardancy compared with traditional flame retardants, and it will pave the way to the design of inorganic–organic hybrid polymer nanocomposites with enhanced flame retardancy and thermal stability. Copyright © 2011 John Wiley & Sons, Ltd.     

Characterization of poly(vinyl pyrrolidone‐co‐isobutylstyryl polyhedral oligomeric silsesquioxane) nanocomposites

Poly(vinyl pyrrolidone‐co‐isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP–POSS) were synthesized by one‐step polymerization and characterized using FTIR, high‐resolution ¹H‐NMR, solid‐state ¹³C‐NMR, ²⁹Si‐NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The T_g of the PVP–POSS hybrid is influenced by three main factors: (1) a diluent role of the POSS in reducing the self‐association of the PVP; (2) a strong interaction between the POSS siloxane and the PVP carbonyl, and (3) physical aggregation of nanosized POSS. At a relatively low POSS content, the role as diluent dominates, resulting in a decrease in T_g. At a relatively high POSS content, the last two factors dominate and result in T_g increase of the PVP–POSS hybrid. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2208–2215, 2004