Temperature-, pH-, and Magnetic-Field-Sensitive Hybrid Microgels

We demonstrate a simple route for the preparation of novel hybrid particles with multiple sensitivities. Aqueous polymeric microgels are modified by magnetite nanoparticles in the preparation of temperature‐ and pH‐sensitive hybrids with a high magnetic response. Up to 15 wt % of magnetite nanoparticles are loaded into microgels. The influence of the amount of magnetite in the microgel structure on the morphology and colloidal properties is discussed. The presence of the magnetite nanoparticles in the microgel decreases its degree of swelling and shifts the volume phase‐transition temperature to higher values. Nanostructured composite films with controlled morphologies can be prepared by water evaporation and deposition of the hybrid microgels on a solid substrate. Multiple sensitivity: Polymeric microgels with temperature and pH sensitivity can be modified by magnetite nanoparticles. Microgel particles containing 8.41 wt % Fe3O4 (see TEM image) demonstrate that the nanoparticles are located in the thermosensitive microgel shell. The microgels have high magnetization values and are able to change their dimensions reversibly in response to temperature and pH.