Figure 23.
(A) Design and synthesis of magnetic nanoparticles grafted with acrylamide (Am) and n-butyl acrylate (BA) copolymers. (top) Functionalization of oleic acid (OA) MNPs with a chain-transfer agent (CTA) to yield CTA MNPs. (center) Synthesis of BAAm copolymer functionalized MNPs. (bottom) Hydrogen bonding between Am and BA are shown as representative examples. (B) Digital photographs showing the actuation of BAAm-MNP-75 sample using 2.54 cm3 neodymium magnet (54 kg pull force). Grid in background is for measuring distance. A dog-bone sample was affixed in position in (i) a parallel view and (ii) perpendicular view. (iii) Magnet was placed on the 3 cm mark and (iv) moved to the 2 cm mark where actuation starts and (v) finishes in less than 30 s. (vi) Magnet was placed on the opposite side and (vii) moved closer by 0.5 cm (viii), then by 1 cm where actuation occurred. (ix) Finally, the magnet was removed from area and the sample resumed to its original position. Adapted and modified with permission from ref (232). Copyright 2020 Royal Society of Chemistry.