No abstract

The syntheses of a family of highly ordered mesoporous polymers and carbon frameworks from organic−organic assembly of triblock copolymers with soluble, low-molecular-weight phenolic resin precursors (resols) by an evaporation induced self-assembly strategy have been reported in detail. The family members include two-dimensional hexagonal (space group, p6m), three-dimensional bicontinuous (Ia3̄d), body-centered cubic (Im3̄m), and lamellar mesostructures, which are controlled by simply adjusting the ratio of phenol/template or poly(ethylene oxide)/poly(propylene oxide) in the templates. A five-step mechanism from organic−organic assembly has been demonstrated. Cubic FDU-14 with a gyroidal mesostructure of polymer resin or carbon has been synthesized for the first time by using the copolymer Pluronic P123 as a template in a relatively narrow range. Upon calcination at 350 °C, the templates should be removed to obtain mesoporous polymers, and further heating at above a critical temperature of 600 °C transforms the mesoporous polymers to the homologous carbon frameworks. The mesoporous polymer resin and carbon product materials exhibit ordered structures, high surface areas, (670−1490 m2/g), large pore volumes (0.65−0.85 cm3/g), and uniform, large pore sizes (7.0−3.9 nm), as well as very thick pore walls (6−8 nm). The carbon open frameworks with covalently bonded constructions and thick pore walls exhibit high thermal stability (>1400 °C). Our results show that the feed gas used during the calcination has a great influence on the porosity of the products. The presence of a small amount of oxygen facilitates the large pore sizes and high surface areas of mesoporous materials with different mesostructures. An extraction method employing sulfuric acid can also decompose the template from hexagonal mesostructured polymers with little framework shrinkage. Preliminary studies of the mechanical and electrochemical properties of mesoporous carbon molecular sieves are also presented.

Highly ordered mesoporous polymer-silica and carbon-silica nanocomposites with interpenetrating networks have been successfully synthesized by the evaporation-induced triconstituent co-assembly method, wherein soluble resol polymer is used as an organic precursor, prehydrolyzed TEOS is used as an inorganic precursor, and triblock copolymer F127 is used as a template. It is proposed for the first time that ordered mesoporous nanocomposites have "reinforced concrete"-structured frameworks. By adjusting the initial mass ratios of TEOS to resol, we determined the obtained nanocomposites possess continuous composition with the ratios ranging from zero to infinity for the two constituents that are "homogeneously" dispersed inside the pore walls. The presence of silicates in nanocomposites dramatically inhibits framework shrinkage during the calcination, resulting in highly ordered large-pore mesoporous carbon-silica nanocomposites. Combustion in air or etching in HF solution can remove carbon or silica from the carbon-silica nanocomposites and yield ordered mesoporous pure silica or carbon frameworks. The process generates plenty of small pores in carbon or/and silica pore walls. Ordered mesoporous carbons can then be obtained with large pore sizes of approximately 6.7 nm, pore volumes of approximately 2.0 cm(3)/g, and high surface areas of approximately 2470 m(2)/g. The pore structures and textures can be controlled by varying the sizes and polymerization degrees of two constituent precursors. Accordingly, by simply tuning the aging time of TEOS, ordered mesoporous carbons with evident bimodal pores at 2.6 and 5.8 nm can be synthesized.