Effect of Areal Chain Density on the Location of Polymer-Modified Gold Nanoparticles in a Block Copolymer Template

Abstract

A strategy for controlling the location of gold nanoparticles within block copolymer domains through varying the surface coverage of gold nanoparticles by end-attached polymer ligands is described. Gold nanoparticles coated by short thiol end functional polystyrene homopolymers (PS-SH) (M n ) 3.4 kg/mol) are incorporated into a poly(styrene-b-2-vinylpyridine) diblock copolymer template (PS-b-P2VP) (M n ) 196 kg/mol), the P2VP block of which has a more favorable interaction with a bare gold particle surface than does the PS block. The areal chain density of the PS-SH ligands on gold particles is varied by changing the mole ratio of PS-SH chains to gold atoms. It is found that the areal density of PS chains on the gold particles is critical to controlling their location in block copolymer templates. PS-coated gold nanoparticles with PS chain areal density higher than 1.6 chains/nm 2 are dispersed in PS domains of PS-b-P2VP while they are segregated along the interface between PS and P2VP domains of PS-b-P2VP for PS chain areal density <1.3 chains/nm 2 . Even at extremely low grafting densities of polymer ligands, gold nanoparticles can be stabilized in solution, and self-assembly of these nanoparticles can be controlled within the block copolymer template.

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

“…Additionally, the inorganic Au core allows facile determination of the location of the nanoparticles by TEM. [11][12][13][14] Poly(ethylene oxide)-coated Au nanoparticles were therefore incorporated into poly(styreneb-methyl methacrylate) (PSt-b-PMMA) diblock copolymers exhibiting a morphology consisting of cylindrical microdomains of PMMA in PSt. In this case, the PEO chains in Au-PEO are miscible with PMMA block in PSt-b-PMMA and have a strong repulsive interaction with the PSt block.…”

“…This can be compared with the recent study on the self-assembly of PS-coated gold nanoparticles within PSt-b-P2VP diblock copolymers. [11][12][13][14] In that case, near equilibrium morphologies could be obtained by slow evaporation of a neutral solvent. In contrast, the ordering of thin films in the system described above was achieved by fast evaporation of solvent under a high humidity condition.…”

Healing substrates with mobile, particle-filled microcapsules: designing a ‘repair and go’ system

“…As noted earlier, ideal nanoparticles for this application could be Janus beads (Perro et al 2005), or hydrophilic particles with a low surface coverage of labile hydrophobic ligands (Kim et al 2006). These particles can bind to the exposed sublayer through the hydrophobic moieties, exposing a hydrophilic portion to the fluid and the capsule.…”

“…This will lower the interfacial energy within the system and thus promote the passage of the capsules over the damaged area. More specifically, if we consider the microcapsules and the adhesive coating to be hydrophilic, then the ideal particles could be Janus beads (Perro et al 2005), which are half hydrophobic and half hydrophilic, or Designing a 'repair and go' system R. Verberg et al 353 hydrophilic particles with a low surface coverage of labile hydrophobic ligands, which become localized in one region when they come in contact with the hydrophobic surface (Kim et al 2006). In both scenarios, one portion of the particles would bind to the hydrophobic substrate and the hydrophilic 'face' would be exposed to the fluid.…”

Block copolymer/ferroelectric nanoparticle nanocomposites

“…The rst approach involves the in situ synthesis of NPs within a BCP domain containing the NP precursors. 12 In contrast, the second approach uses the cooperative self-organization of preformed NPs and BCPs, 12 where the location of NPs within the BCP can be controlled by exploiting the enthalpic interaction between the BCP and the surface-modied (e.g., polymer-coated) NPs. 11 The polymeric ligands on the NP surface control and stabilize the NP formation, allowing the initial small size to be retained by preventing NPs from aggregation.…”