Solvent‐Induced Self‐Assembly Strategy to Synthesize Well‐Defined Hierarchically Porous Polymers

Abstract

Porous polymers with well‐orchestrated nanomorphologies are useful in many fields, but high surface area, hierarchical structure, and ordered pores are difficult to be satisfied in one polymer simultaneously. Herein, a solvent‐induced self‐assembly strategy to synthesize hierarchical porous polymers with tunable morphology, mesoporous structure, and microporous pore wall is reported. The poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) diblock copolymer micelles are cross‐linked via Friedel–Crafts reaction, which is a new way to anchor micelles into porous polymers with well‐defined structure. Varying the polarity of the solvent has a dramatic effect upon the oleophobic/oleophylic interaction, and the self‐assembly structure of PEO‐b‐PS can be tailored from aggregated nanoparticles to hollow spheres even mesoporous bulk. A morphological phase diagram is accomplished to systematically evaluate the influence of the composition of PEO‐b‐PS and the mixed solvent component on the pore structure and morphology of products. The hypercrosslinked hollow polymer spheres provide a confined microenvironment for the in situ reduction of K2PdCl4 to ultrasmall Pd nanoparticles, which exhibit excellent catalytic performance in solvent‐free catalytic oxidation of hydrocarbons and alcohols.

Holey Lamellar High‐Entropy Oxide as an Ultra‐High‐Activity Heterogeneous Catalyst for Solvent‐free Aerobic Oxidation of Benzyl Alcohol

“…It can be observed that the quaternate catalysts only show ac onversion of about 20 % after 24 ho fc atalytic reaction and the lack of arbitrary one element has the similar influence on the catalytic activity. Furthermore,t he single component and two,t hree components catalysts exhibit poorer catalytic performance,a nd the conversions are as low as the bulk HEO.T he above catalytic [26] Pd/GC, [27] Au/MnO 2 -R, [28] Au 1 /CeO 2 , [29] Pd/mHCPs, [30] Au(8 wt %)/U 3 O 8 , [31] 1% (Au + Pd)/C, [32] 0.5 %Pd@C-Glu A -550 [33] ). c) Catalytic performance of holey HEO in benzyl alcohol, methylbenzyl alcohol, methoxy benzyl alcohol, and nitrobenzyl alcohol oxidation.…”

“…In the absence of catalyst, the conversion of benzyl alcohol is lower than 1%.E ncouragingly,w ith the addition of the holey lamellar HEO catalyst, the catalytic conversion increases exponentially with increasing reaction temperature from 100 8 8Ct o1 20 8 8C( Supporting Information, Table S2), and up to 98 %c onversion can be achieved after reaction at 120 8 8Cf or only 2hunder solventfree atmospheric conditions.T ot he best of our knowledge, this is the highest reported conversion among previous reported single-atom, cluster,noble-metal, and alloy catalysts (Figure 2b;Supporting Information, Table S3). [26][27][28][29][30][31][32][33] It should be pointed out that the reported TOFn umbers were calculated on the basis of loading amount of noble metals (loading rate = 0.5-5 wt %), and the metal oxides just act as supports,n ot catalytic active materials.H owever,n oble metals do not exist in this catalytic system, and the TOF value can only be calculated to be 994 in terms of the amount of HEO.A u/Pd-TiO 2 catalyst, whose conversion is 91.6 %i n 8hunder 0.2 MPa of O 2 ,i st he most advanced catalyst ever reported. [26] Compared with Au/Pd-TiO 2 catalyst, the holey lamellar HEO catalyst not only works at atmospheric pressure,b ut also reaches the equilibrium of the catalytic reaction in less time.T here are three products in this oxidation process:b enzaldehyde,b enzoic acid, and benzyl benzoate.B enzoic acid is the dominant product in the catalytic reaction, benzaldehyde and benzyl benzoate are identified as the major byproducts.Inthe reaction process,the benzyl benzoate is formed by the esterification of benzyl alcohol with benzoic acid.…”

Self‐Assembly of Multiblock Copolymers

“…For example, by controlling the solvent polarity, the morphology of assembled PEO‐ b ‐PS can be adjusted from spherical micelles to hollow spheres to inverted mesoporous morphologies with large interfacial area . These properties are in great demand for a wide range of applications, such as catalysis or drug delivery . For applications in surface science, biomedicine and nanotechnology, more attention has recently been directed to 2D nanomaterials.…”

“…[101] These properties are in great demand for a wide range of applications, such as catalysis or drug delivery. [102,103] For applications in surface science, biomedicine and nanotechnology, more attention has recently been directed to 2D nanomaterials. Again, the self-assembly of AB diblock copolymers proved to be a promising field of research.…”

Active Nanointerface‐Assisted Co‐Assembly to Yolk–Shell Au@Ordered Mesoporous Carbon Nanospheres

“…This is motivated by that hierarchically structured materials exhibit the advantage of each component with synergistic effect and lead to diversified or even unconventional capabilities for multitask applications. Integration of porous structure into the hierarchical materials is particularly appealing, since it can not only provide large surface area for dispersion of active sites but also serve as fast paths for guest molecules into the heterogeneous substances . For instance, the construction of porous carbon shell coated onto 1D carbon nanotube induces formation of a hierarchically carbonaceous structure .…”