Arrangement of Maghemite Nanoparticles via Wet Chemical Self-Assembly in PS-b-PNIPAM Diblock Copolymer Films

Abstract

The structure and magnetic behavior of hybrid films composed of maghemite (γ-Fe2O3) nanoparticles (NPs) and an asymmetric diblock copolymer (DBC) polystyrene61-block-polyN-isopropylacrylamide115 are investigated. The NPs are coated with PS chains, which allow for a selective incorporation inside the PS domains at different NP concentrations. Upon incorporation of low amounts of NPs into the DBC thin films, the initial parallel (to film surface) cylinder morphology changes to a well ordered, perpendicularly oriented one. The characteristic domain distance of the DBC is increased due to the swelling of the PS domains with NPs. At higher NP concentrations, the excess NPs which can no longer be embedded in the PS domains, are accumulated at the film surface, and NP aggregates form. Irrespective of NP concentration, a superparamagnetic behavior of the metal oxide-DBC hybrid films is found. Such superparamagnetic properties make the established hybrid films interesting for high density magnetic storage media and thermoresponsive magnetic sensors.

Three‐Layered Hollow Nanospheres Based Coatings with Ultrahigh‐Performance of Energy‐Saving, Antireflection, and Self‐Cleaning for Smart Windows

“…Inspired by our previous studies, [15] SiO 2 /TiO 2 /VO 2 TLHNs with unique architecture design were prepared by a facile solution-based method. In the synthesis protocol (Figure 1a), polyacrylic acid (PAA) was used as a template and enclosed by the precursors of SiO 2 , TiO 2 , and VO 2 in succession.…”

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

“…Similar orientationdriving effects were seen in a system with C-type (a mixture of TOPO and oleylamine) homopolymer ligands in A-b-B (A is n-pentyl methacrylate and B is methyl methacrylate) film, although solvent vapor annealing was used in this case. [134] In another work by Yao et al, [135] 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 [136] via solvent vapor annealing.…”

Segregation of Maghemite Nanoparticles within Symmetric Diblock Copolymer and Triblock Terpolymer Patterns under Solvent Vapor Annealing

“…Enthalpic and entropic factors both determine the spatial placement of the nanoparticles to the final BCP/NPs nanocomposites, which is extensively described in the literature [7][8][9][10][11][12][13][14][15][16][17][18]. More specifically, the NPs dispersion and localization on a specific block of the BCP host or on the interface between the different blocks is dependent on balancing the conformational entropy of the BCP host, the inclusion enthalpy of the NPs, as well as the NPs translational entropy [19,20]. Such behavior of the NPs induces morphological changes on the BCP host, which depends on the chemical affinity between the NPs and the chemically different domains of the BCP host.…”

“…There are many scientific results that are reported in the literature concerning magnetic NPs as embedding fillers into BCP matrices [13,17,[20][21][22][23], but they are limited to the MNPs encapsulation within AB- [24][25][26] or ABA-type BCPs [27,28]. Taking advantage of the BCPs periodic structures, higher complexity arises upon the transition from two to three chemically different domains for the BCP host matrix (going from AB diblock copolymers to ABC triblock terpolymers).…”