SI-RAFT Synthesis of Poly(methyl acrylate)-Grafted Gold Nanorods

Grafted polymers have a wide range of applications, including reducing energy consumption and altering the mechanical properties of materials. While the conformation and relaxation dynamics of polymers grafted to planar surfaces and spherical cores are well characterized, these properties are less understood for anisotropic shapes such as nanorods. To investigate this, poly(methyl acrylate) (PMA) was grafted from the surface of gold nanorods (AuNRs) via surface-initiated reversible addition–fragmentation chain-transfer (SI-RAFT) polymerization using functionalized chain transfer agents (CTAs) to control grafting density. Depolarized dynamic light scattering (DDLS) of the resulting polymer-grafted nanorods (PGNRs) provided translational and rotational diffusion coefficients, from which their dimensions were estimated. Comparison of these preliminary DDLS results with bare AuNR dimensions obtained from SEM imaging and small-angle neutron scattering (SANS) suggests a PMA brush height consistent with theoretical predictions for polymers grafted onto spherical rather than planar surfaces. These results establish an SI-RAFT method that can be extended to other molecular weights, thermoresponsive polymers, and AuNRs with varied aspect ratios.