Magnetic nanoparticle-containing soft–hard diblock copolymer films with high order

Abstract

For sensor applications, superparamagnetic anisotropy is an indispensable property, which is typically achieved by employing an external field to guide the arrangement of magnetic nanoparticles (NPs). In the present investigation, the diblock copolymer polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAM) is printed as a template to localize magnetic iron oxide NPs without any external field. Via microphase separation, cylindrical nanostructures of PS in a PNIPAM matrix are obtained, aligned perpendicular to the substrate. Since the magnetite NPs (Fe3O4) are functionalized with hydrophobic organic chains showing affinity to the PS blocks, they can selectively aggregate inside the PS cylinders. Moreover, solvent vapor annealing allows the achievement of nanostructures inside the hybrid system with a very high order, even at a high NP loading. Therefore, NPs can accumulate within PS domains to form perpendicularly aligned aggregates with high periodicity. The magnetic properties of the hybrid films are determined at various temperatures in two orthogonal directions (with PS cylinders vertical and parallel to the applied magnetic field). All hybrid films show superparamagnetism and a remarkable magnetic anisotropy is achieved at certain NP concentrations. This investigation shows a facile route to prepare superparamagnetic films with magnetic anisotropy and offers a novel possibility to future magnetic sensor fabrication.

Polymer Micelle Directed Magnetic Cargo Assemblies Towards Spin‐wave Manipulation

“…[ 46 ] In particular, Müller‐Buschbaum and coworkers. [ 41,47 ] nicely demonstrated the use of real space imaging analysis to understand the morphological evolution of block copolymer thin films upon nanoparticle incorporation. In summary, local surface analysis by AFM and TEM correlated well and led to an understanding that: at POM/polymer mass ratios of ≤0.5, POMs are either located at the PS‐P2VP intephase or well embedded into the corona of the PS phase.…”

Tailoring Ordered Mesoporous Titania Films via Introducing Germanium Nanocrystals for Enhanced Electron Transfer Photoanodes for Photovoltaic Applications

“…This increase in the interdomain distance and distribution width is similar to the DBC templating of magnetic nanoparticles reported previously. [34,43] Based on the model used above, the average pore size is calculated with Equation (S1), Supporting Information (details can be found here). [25] For air-annealed and argon atmosphereannealed films, we find that the pore sizes originating from small-sized structures are independent of the GeNC content (Figure S7a,b, Supporting Information; olive crosses).…”

Thermal Approaches to Perpendicular Block Copolymer Microdomains in Thin Films: A Review and Appraisal

“…In another work by Yao et al., magnetic NPs with A‐type (styrene) ligands were incorporated selectively into the cylindrical A domains of A‐ b ‐B (B is N ‐isopropylacrylamide) to produce perpendicular cylinders straight after spin coating. The spatial ordering of this nanocomposite film was improved by Xia et al . via solvent vapor annealing.…”