Gold nanoparticles and polymers from RAFT polymerization form various types of self-assembled nanostructures, depending on the surface reactivity of the gold particles as well as on the microstructure and topology of the RAFT polymer. When using linear polyNIPAM and gold particles from citrate reduction, perfectly hexagonal lattices of gold cores are formed. The inter-particle distances increased strictly correlated with growing molar masses of the coating polymer, allowing for a reference curve to be found. When using polymers containing multiple RAFT groups along their backbone, the spacing between the gold cores are much lower and remain constant, independent of the polymers' chain lengths, showing that these macromolecules are wrapped around the nanoparticles. Absolutely no crosslinking is observed for this case. However, when increasing the surface reactivity of the gold particles by generating them via the Brust-Schiffrin method, a self-assembly of RAFT multi-block polymers with gold particles into dispersed three-dimensional superstructures occurs (see figure). Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/mwrm/uploads/60177_acs_fig_1.jpg' alt='' /> TEM analysis revealed that the inter-particle distances in these superstructures can again be tuned over an unprecedented wide range by employing multi-block polymers with adjusted degree of polymerization and thus tailored RAFT group distances. Cross-linking of the gold nanoparticles in the assemblies was proven by AFM showing partly preserved globular shape after deposition on a solid substrate.

Tailoring nanocomposites using RAFT: Super-assemblies of gold nanoparticles and multiblock copolymers

248th National Meeting (2014)

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