Tailored Mesoporous Microspheres by Polymerization-Induced Microphase Separation in Suspension

Colin H. Peterson, Jay R. Werber, Hyung Kae Lee, Marc A. Hillmyer

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We describe the preparation of block polymer beads by aqueous suspension polymerization to create poly(caprolactone) (PCL)-block-poly(styrene-co-divinylbenzene) beads that can be selectively etched under basic conditions to yield mesoporous polymer microspheres with uniform pore size. Polyvinylalcohol was used to stabilize the suspension polymerization in which styrene and divinylbenzene monomers were polymerized from a PCL macrochain transfer agent (macroCTA). The resulting polymerization-induced microphase separation process led to a nanostructured bicontinuous morphology. The particle size and pore size were independently tunable: the particle size was controlled by the stir rate of the suspension polymerization-yielding average diameters ranging from 60 to 300 μm-while the pore size was determined by the molar mass of the PCL block, with the mode pore diameters being 6 nm and 11 nm after etching beads made using 13 and 45 kg/mol PCL blocks, respectively. Based on nitrogen sorption measurements, the surface areas of the beads were ∼300 m2/g when using a PCL macroCTA of 13 kg/mol. The beads were homogenous throughout on the micron length scale as determined by confocal Raman microscopy and lacked an impermeable skin layer as confirmed by scanning electron microscopy. Furthermore, the scalability of suspension polymerization allows for the simple synthesis of large quantities of thermoset microspheres with uniform pore size. We also demonstrate the ability to incorporate functional pore walls into the beads using multiblock precursor polymers. These functionalized mesoporous polymer beads show high affinity for ionic dyes in aqueous solutions (as a proof of principle) and remove dye from the solution at rates exceeding those of commercial ion-exchange resins. The developed procedure could be used to generate other functional surface chemistries with important applications in heterogeneous catalysis, chromatography, and water remediation.

Original languageEnglish (US)
Pages (from-to)4219-4233
Number of pages15
JournalACS Applied Polymer Materials
Issue number6
StatePublished - Jun 10 2022

Bibliographical note

Funding Information:
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0020210. We thank Bing Luo for assistance with Raman microscopy and Fang Zhou for the preparation of microtome samples. We also acknowledge the Research Analytical Laboratory of the Department of Soil, Water, and Climate for the performance of combustion analysis. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from the NSF through the MRSEC program. This work benefited from the use of the SasView application, originally developed under the NSF award DMR-0520547. SasView contains code developed with funding from the European Union’s Horizon 2020 research and innovation program under the SINE2020 project, grant agreement no 654000.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.


  • block polymers
  • controlled radical polymerization
  • Ion exchange
  • mesoporous materials
  • polymer microspheres
  • suspension polymerization

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