Janus Magnetic Nanoparticles with a Bicompartmental Polymer Brush Prepared Using Electrostatic Adsorption to Facilitate Toposelective Surface-Initiated ATRP
Utilizing the inherent negative charge of mica surfaces, amine-functionalized magnetic nanoparticles (Fe3O4/NH2) were electrostatically adsorbed onto the mica such that surface-initiated ATRP could be used to grow poly(n-isopropylacrylamide) (PNIPAM) from the exposed hemisphere. By reducing the solution pH, a positive charge generated on the mica was used to release the nanoparticles from the substrate. A second ATRP reaction was carried out to grow poly(methacrylic acid) (PMAA) from the initiated surfaces. As a result, the Fe3O4/NH2 core has a polymer shell with one hemisphere PMAA and the other hemisphere PNIPAM-b-PMAA resulting in the PMAA–Fe3O4–PNIPAM-b-PMAA bicompartmental polymer Janus nanoparticles. Elemental and functional group compositions were confirmed using ATR-FTIR, XPS, and EDS. Imaging with AFM, SEM, and TEM showed the evolution of the Janus nanoparticle morphology. This study demonstrates a facile and innovative scheme involving a noncovalent solid protection technique combined with sequential, surface-confined controlled radical polymerizations for the production of multicomponent nanocomposites.
0743-7463 (print); 1520-5827 (web)
This work was supported by the National Science Foundation (EPS-0556308, EPS-0903787, and CBET-0923474). We gratefully acknowledge the Mississippi State University (MSU) Bagley College of Engineering Ph.D. Fellowship Program. Staff at MSU’s Institute for Imaging and Analytical Technologies (I2AT) assisted with a portion of the AFM and TEM characterization.
Vasquez, Erick S.; Chu, I-Wei; and Walters, Keisha B., "Janus Magnetic Nanoparticles with a Bicompartmental Polymer Brush Prepared Using Electrostatic Adsorption to Facilitate Toposelective Surface-Initiated ATRP" (2014). Chemical and Materials Engineering Faculty Publications. 232.