(560c) Monte Carlo Simulations of Assembly of Copolymer Functionalized Spherical Nanoparticles

Functionalizing nanoparticle surfaces with organic ligands, such as oligomers, polymers, DNA, and proteins, is an attractive method to control the assembly of nanoparticles. While much of the past work in this area of functionalized nanoparticles has been focused on homopolymer grafted nanoparticles, and the role of grafting density and molecular weight on the particle assembly, the behavior of copolymer grafted nanoparticles remains largely unexplored. We use Monte Carlo simulations to study spherical nanoparticles functionalized with AB copolymers. We first study the effect of various molecular parameters, such as monomer sequence, molecular weight, and monomer interactions of the grafted copolymer as well as particle size on the conformations of the grafted copolymer chains. Our results show that monomer sequence, particle diameter, and grafting density dictate whether a) the grafted chains aggregate to bring attractive monomers from multiple grafted chains together (interchain and intrachain monomer aggregation) if the enthalpy gained by doing so offsets the entropic loss caused by the stretching of the chains or b) each grafted chain folds onto itself to bring its attractive monomers together (purely intrachain monomer aggregation) if the entropic loss from interchain aggregation cannot be overcome by the enthalpic gain [1]. This single molecule study is followed by simulations of assembly of multiple copolymer grafted spherical nanoparticles in an implicit small molecule solvent. We study the effect of the varying parameters, graft monomer sequence, graft molecular weight, monomer interactions and particle size, on the assembly of copolymer grafted nanoparticles. We characterize the assembled structures through the cluster shape and size distribution. In this talk we will present results from these simulations of a single copolymer grafted nanoparticle [1] and of the assembly of multiple copolymer grafted nanoparticles.

1. A. Seifpour, P. Spicer, N. Nair, A. Jayaraman, 'Effect of monomer sequences on conformations of copolymers grafted on spherical nanoparticles: A Monte Carlo simulation study' J. Chem. Phys. 132, 164901 (2010)