Ordered Mesoporous Carbons via Self-Assembly of Tailored Block Copolyethers for Pore Size-Dependent Applications

Abstract

Using an organocatalytic polymerization method for the preparation of well-defined, amphiphilic block copolyethers of the type PPO n/2 -PEO m -PPO n/2 ("Reverse Pluronics", M n up to 50 000 g/mol, Đ M = 1.01−1.08, >100 examples), it is demonstrated that the application of these polymers as structure-directing agents (SDAs) in a standard softtemplating process delivers ordered mesoporous carbons (OMCs), whereby the resulting pore diameters are monomodal and narrowly distributed. Moreover, by the judicious choice of the SDA properties (total molar mass, ratio of n and m, and PPO block length), pore diameters in the range of 6−18 nm can be selectively addressed, notably within the same arrangement pattern (2D hexagonal, p6mm). This provides a rational, operationally simple method to tailor pore properties of otherwise uniform carbons, also significantly reducing the effort necessary to obtain systematically altered materials. Ready access to such quick screenings is assumed to be immensely useful for pore size-dependent applications from numerous disciplines such as sensing, catalysis, or energy storage and conversion. Surprisingly, it is not only found that a minimum of M n = 13 000 g/mol is required to deliver ordered (nondistorted) materials under these conditions but also that very high-molar-mass SDAs are best suited to achieve optimum results, potentially providing an explanation for why "Reverse Pluronics" are frequently, and wrongly, thought to be per se unsuitable for the preparation of well-ordered mesoporous carbons.

Predictive design of ordered mesoporous silica with well-defined, ultra-large mesopores

“…While the size of the hydrophobic block affects the pore diameter, it is necessary to adjust the degree of polymerization of the hydrophilic block simultaneously to maintain the surface-active properties of the polymer. 66 With this in mind, we designed and synthesized numerous reverse poloxamers (PPO n /2 –PEO m –PPO n /2 ) with variations regarding the terminal hydrophobic polypropylene oxide (PPO) and the hydrophilic polyethylene oxide (PEO block lengths employing a recently developed, metal-free polymerization approach (Fig. 1).…”

Influence of the Silicon–Carbon Interface on the Structure and Electrochemical Performance of a Phenolic Resin-Derived Si@C Core–Shell Nanocomposite-Based Anode

“…Synthesis of Si@C Materials. 4.0 g of a phenolic resin precursor, freshly prepared from phenol and formaldehyde, 19 was dissolved in ethanol to give a 20 wt % solution. 1.0 g pristine/silanol-rich/epoxide-rich Si nanoparticles were immersed into the solution and treated in an ultrasonic bath for 30 min.…”

Recent progress in block copolymer soft-template-assisted synthesis of versatile mesoporous materials for energy storage systems

“…[112][113][114][115] To solve this issue, hard-template and so-template methods that can maintain the mesoporous structure during the reaction of precursors have been proposed. [116][117][118][119] Hard-templating methods use thermally stable templates such as pre-synthesized mesoporous silica, carbon, and metal oxide-based nanocrystals (Fig. 1a).…”

“…112–115 To solve this issue, hard-template and soft-template methods that can maintain the mesoporous structure during the reaction of precursors have been proposed. 116–119…”