Preparation of pore size controllable macroporous polymer beads

Macroporous polymer beads have been used in various fields, for example as solid supports in solid-phase organic synthesis and heterogeneous catalysts and as adsorbents in column chromatography. Their broad applications have stimulated many researchers to develop various kinds of macroporous polymer beads. However, despite all the efforts, it is still hard to control the porosity and pore size distributions within the polymer beads. In this study, we prepared pore size controllable macroporous poly(methyl methacrylate-co-methyl methacrylic acid) (PMMA-co-PMAA) beads. First, we prepared silica submicron particles embedded PMMA beads by the polymerization of methyl methacrylate monomer with mono-dispersed silica particles. Then, the silica NP embedded PMMA beads were hydrolyzed with sodium hydroxide to obtain a macroporous structure by removing the embedded silica particles. At the same time, part of the methyl methacrylate turned into methacrylic acid, which caused the PMMA beads to become PMAA-co-PMMA beads. Through this method, two types of beads having different pore sizes were prepared as a model study. The pore size of the beads could be easily controlled by adjusting the size of the silica particles.