Self-directed self-assembly of nanoparticle/copolymer mixtures

Abstract

The organization of inorganic nanostructures within self-assembled organic or biological templates is receiving the attention of scientists interested in developing functional hybrid materials. Previous efforts have concentrated on using such scaffolds to spatially arrange nanoscopic elements as a strategy for tailoring the electrical, magnetic or photonic properties of the material. Recent theoretical arguments have suggested that synergistic interactions between self-organizing particles and a self-assembling matrix material can lead to hierarchically ordered structures. Here we show that mixtures of diblock copolymers and either cadmium selenide- or ferritin-based nanoparticles exhibit cooperative, coupled self-assembly on the nanoscale. In thin films, the copolymers assemble into cylindrical domains, which dictate the spatial distribution of the nanoparticles; segregation of the particles to the interfaces mediates interfacial interactions and orients the copolymer domains normal to the surface, even when one of the blocks is strongly attracted to the substrate. Organization of both the polymeric and particulate entities is thus achieved without the use of external fields, opening a simple and general route for fabrication of nanostructured materials with hierarchical order.

Characterisation of particles in solution – a perspective on light scattering and comparative technologies

“…However, the technique can detect and analyse samples with very low concentrations which may not be detectable by light scattering methods [35]. Small-angle X-ray scattering (SAXS) can also be used to determine NP sizes and concentrations [36–38]. …”

Optical Properties of Composites of PMMA and Surface-Modified Zincite Nanoparticles

“…This behavior has been experimen-tally documented by many authors and has been the subject of theoretical treatment. [12][13][14][15] While segregation of nanosized particles into specific domains of a multiphase system is reasonably understood, it remains still a puzzle what drives such particles to undergo reversible or irreversible association in a homogeneous polymer matrix. Theoretical treatments can be found in the recent literature for instance by Schweizer et al 16 and Balazs et al 17 However, experimental investigations that would allow to verify theoretical predictions are scarce and, in fact, difficult to obtain for the reason that suitable combinations of nanosized particles of precisely known surface properties and polymer matrices cannot be readily found.…”

Controlled Ordering of Block Copolymer Thin Films by the Addition of Hydrophilic Nanoparticles

“…[11][12][13][14] In addition to controlling the location of the nanoparticles, it would be highly desirable if the nanoparticles could also play an "active" role in the self-assembly process, such as directing the morphology and orientation of microstructures. In this regards, pioneering work has been performed by Emrick and Russell, 15 where incorporation of cadmium selenide nanoparticles into block copolymer thin films can mediate interfacial interactions and control the orientation of microdomains. More recently, Kim showed that stable bicontinuous morphologies with nanoscale dimensions can be fabricated by the addition of "neutral" nanoparticles which are directed to and stabilize the interface between diblock copolymers.…”