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 K₂ PdCl₄ to ultrasmall Pd nanoparticles, which exhibit excellent catalytic performance in solvent-free catalytic oxidation of hydrocarbons and alcohols.