Preparation And Properties Of The POSS-based Nanocomposites Via Friedel-Crafts Alkylation Reaction

Polyhedral oligomeric silsesquioxanes (POSS) are novel kind of nano-scale inorganic-organic hybrids and they have been widely used to prepare varieties of POSS-based polymers and POSS-containing functional materials due to their unique characteristics of thermal stability, chemical stability, low dielectric properties and excellent biocompatibility. The study of POSS is an important integral part of nanocomposites. It has great significance in theory and application to select the new method for preparing the novel POSS monomers, developing the high performance POSS-based polymers and especially developing the POSS-containing polymers with special functionalities. In the present dissertation, two aspects had been focused. One was to prepare octaphenethyl POSS via the Friedel-Crafts alkylation reaction and use it to develop the novel POSS-based polymers. The other was to synthsize a series of POSS-based functional materials and particularly preparing the porous POSS-containing polymers through the Friedel-Crafts alkylation reaction.1. The octaphenethyl POSS was prepared via Friedel-Crafts reaction by using octavinyl POSS and benzene as the starting materials. The POSS-based nanocomposites were prepared by solution blending of novolac resin and octaphenethyl POSS. FT-IR, POM, XRD and DSC were used to characterize the specific hydrogen bonding interaction, morphology and miscibility of phenolicresin/POSS nanocomposites before curing. The results indicated that there existed intermolecular hydrogen bonding interactions between the hydroxyl groups of the phenolic resin and Si-O-Si groups of POSS, which could promote POSS to disperse well in the polymer matrix up to20wt%POSS loading. At higher POSS loading, POSS would aggregate and lead to macrophase separation. Finally, the hexamethylene tetramine was used to cure the phenolic resin/POSS nanocomposites to form the network structure. The miscibility was also characterized by FT-IR and SEM. The results showed that the curing process prompted phase separation between the phenolic resin and POSS particles. DMA and TGA were also used to perform the thermal stability and mechanical properties of the cured phenolic resin/POSS nanocomposites.2. A series of hybrid porous polymers (HPPs) were prepared via Friedel-Crafts reaction by using octavinyl POSS and benzene as the starting materials. The structures of hybrid porous polymers were characterized by FT-IR,13C CP/MAS NMR and29Si CP/MAS NMR. The porosities of hybrid porous polymers were determined by the N2sorption-desorption isotherms. The results showed that hybrid porous polymers featured both micro-and mesopores with apparent Brunauer-Emmett-Teller surface areas in a range of400～904m2g-1, with total pore volumes in the range of0.24cm3g-1to0.99cm3g-1. Their porosities can be fine tuned by adjusting the mole ratios of octavinyl POSS and benzene. The XRD, FE-SEM, HRTEM and TGA were also used to perform the morphologies and thermal stabilities of the hybrid porous polymers. The results showed that these polymers were amorphous porous polymers with high thermal stabilities. H2and CO2gas sorption isotherms were used to perform the sorption properties of the porous hybrid polymers. The results showed that the hybrids had preferable sorption properties and could be potentially applied to H2and CO2gas sorption. Finally, the hybrid porous polymers were postfunctionalized via the Thiol-ene Click reaction. The structures and properties of the postfunctionalised hybrid porous polymers were also characterized.3. Eight kinds of the hybrid porous polymers were constructed by using octavinyl POSS and the non-planar molecules of biphenyl and1,3,5-triphenylbenzene via Friedel-Crafts alkylation, respectively. The structures of hybrid porous polymers were characterized by FT-IR,13C CP/MAS NMR and29Si CP/MAS NMR. And the porosities of hybrid porous polymers were tested by the N2sorption-desorption isotherms. The results showed that all hybrid porous polymers HPP-2, HPP-3, HPP-4, HPP-6, HPP-7and HPP-8, featured both micro-and mesopores with apparent Brunauer-Emmett-Teller surface areas in a range of600m2g-1to905m2g-1. The total pore volumes were in the range of0.51cm3g-1to0.55cm3g-1and0.55cm3g-1to0.76cm3g-1, respectively. As far as the hybrid porous polymers synthesized with the same building units, the total pore volumes of the hybrid porous polymers were similar, although the SBET of the hybrid porous polymers can be tuned by adjusting mole ratios of octavinyl POSS and non-planar molecules. The XRD, TGA, FE-SEM, HRTEM were also used to perform the thermal stabities and the morphologies of the hybrid porous polymers. The results show that hybrid porous polymers were featured micro-and mesopores, amorphous polmers with high thermal stability. Gas sorption isotherms were also used to characterize the performaces of the H2and CO2sorption properties of the hybrid porous polymers.4. A variety of hyper-crosslinking polystyrene hybrids were prepared by using octavinyl POSS and polystyrene as building blocks via the Friedel-Crafts alkylation reaction. The structures of polystyrene hybrids porous polymers were characterized by FT-IR,13C CP/MAS NMR and29Si CP/MAS NMR. And the porosities of polystyrene hybrids were investigated by the N2sorption-desorption isotherms. The results show that hybrid porous polymers HPP-1, HPP-2, HPP-6and HPP-7featured both micro-and mesopores with SBET in a range of473m2g-1to767m2g-1, with total pore volumes in the range of0.36cm3g-1to0.90cm3g-1. The TGA, FE-SEM, HRTEM were also used to analyze the thermal stabities and the morphologies of the hybrid porous polymers. The results showed that hybrid porous polymers were amorphous polymers featured micro-and mesopores. Gas sorption isotherms were also used to characterize the performaces of the H2and CO2sorption properties of the hybrid porous polymers.