Nanopod formation through gold nanoparticle templated and catalyzed cross-linking of polymers bearing pendant propargyl ethers

Abstract

A novel method for synthesizing polymer nanopods from a linear polymer bearing pendant propargyl ether groups, using gold nanoparticles as both the template and the catalyst for the cross-linking reaction, is reported. The transformations involved in the cross-linking process are unprecedented on the surface of a gold particle. A tentative cross-linking mechanism is proposed.

Figure 1

A. Dissolution process of polymer-coated 13 nm AuNPs. B. Normalized UV-Vis spectra of AuNPs at various time points during the dissolution process. C. TEM images of a) polymer-coated AuNPs, b-c) partially formed nanopods and d) fully formed nanopods (negatively stained with 0.5% uranyl acetate).

Figure 2

A. Number-average hydrodynamic diameters of AuNPs (13, 20, 30 and 40 nm), polymer-coated AuNPs and polymer nanopods. B. TEM images of a) 20 nm nanopods and b) 40 nm nanopods (negatively stained with 0.5% uranyl acetate). In c) it is illustrated why nanopods appear as donut-shaped in TEM. Black: uranyl acetate stain. Blue: deflated nanopod on a surface.

Figure 3

Tentative crosslinking mechanism. B. A poly(ethylene glycol)₂₄-propargyl ether conjugate model system.

Scheme 1

Synthesis of polyvalent propargyl ether nanopods.