Monodisperse Liquid Crystal Network Particles Synthesized via Precipitation Polymerization

Xiaohong Liu; Yifei Xu; Johan P A Heuts; Michael G Debije; Albert P H J Schenning

doi:10.1021/acs.macromol.9b01852

Monodisperse Liquid Crystal Network Particles Synthesized via Precipitation Polymerization

Macromolecules. 2019 Nov 12;52(21):8339-8345. doi: 10.1021/acs.macromol.9b01852. Epub 2019 Oct 29.

Authors

Xiaohong Liu^{1

2}, Yifei Xu^{1

2}, Johan P A Heuts^{1

2}, Michael G Debije¹, Albert P H J Schenning^{1

2}

Affiliations

¹ Stimuli-Responsive Functional Materials and Devices, Laboratory of Materials and Interface Chemistry and Center for Multiscale Electron Microscopy, and Supramolecular Polymer Chemistry group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
² Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.

Abstract

The production of liquid crystalline (LC) polymer particles with a narrow size distribution on a large scale remains a challenge. Here, we report the preparation of monodisperse, cross-linked liquid crystalline particles via precipitation polymerization. This versatile and scalable method yields polymer particles with a smectic liquid crystal order. Although the LC monomers are randomly dissolved in solution, the oligomers self-align and LC order is induced. For the polymerization, a smectic LC monomer mixture consisting of cross-linkers and benzoic acid hydrogen-bonded dimers is used. The average diameter of the particles increases at higher polymerization temperatures and in better solvents, whereas the monomer and initiator concentration have only minor impact on the particle size. After deprotonating of the benzoic acid groups, the particles show rapid absorption of a common cationic dye, methylene blue. The methylene blue in the particles can be subsequently released with the addition of Ca²⁺, while monovalent ions fail to trigger the release. These results reveal that precipitation polymerization is an attractive method to prepare functional LC polymer particles of a narrow size distribution and on a large scale.