Liquid Crystal-Templated Porous Microparticles via Photopolymerization of Temperature-Induced Droplets in a Binary Liquid Mixture

Porous polymericmicrospheres are an emerging class of materials,offering stimuli-responsive cargo uptake and release. Herein, we describea new approach to fabricate porous microspheres based on temperature-induceddroplet formation and light-induced polymerization. Microparticleswere prepared by exploiting the partial miscibility of a thermotropicliquid crystal (LC) mixture composed of 4-cyano-4 '-pentylbiphenyl(5CB, unreactive mesogens) with 2-methyl-1,4-phenylene bis4-[3-(acryloyloxy)-propoxy]benzoate (RM257, reactive mesogens) in methanol (MeOH). Isotropic5CB/RM257-rich droplets were generated by cooling below the binodalcurve (20 degrees C), and the isotropic-to-nematic transition occurredafter cooling below 0 degrees C. The resulting 5CB/RM257-rich dropletswith radial configuration were subsequently polymerized under UV light,resulting in nematic microparticles. Upon heating the mixture, the5CB mesogens underwent a nematic-isotropic transition and eventuallybecame homogeneous with MeOH, while the polymerized RM257 preservedits radial configuration. Repeated cycles of cooling and heating resultedin swelling and shrinking of the porous microparticles. The use ofa reversible materials templating approach to obtain porous microparticlesprovides new insights into binary liquid manipulation and potentialfor microparticle production.

Automated summary

Porous polymeric microspheres were fabricated using a new approach based on temperature-induced droplet formation and light-induced polymerization. The microspheres were prepared by exploiting the partial miscibility of a liquid crystal mixture composed of 5CB and RM257 in MeOH. The resulting microparticles showed stimuli-responsive behavior, with repeated cycles of cooling and heating causing swelling and shrinking.