Monomer chemical structure (top right), the nanoparticle, as made (top left) and in equilibrium in water. The curves in the center correspond to the static structure factor S(q) as the function of q for polymer substituted (solid triangles) and without (open triangles) side chains in water with best fit to a fuzzy spherical form factor (solid lines).
Gary Grest (in Sandia’s Nanostructure Physics Dept.) and his collaborators published “Internal Correlations and Stability of Polydots, Soft Conjugated Polymeric Nanoparticles” in ACS Macro Letters in July 2013.
In their work, the internal structure of soft, highly luminescent nanoparticles was resolved by molecular dynamics (MD) simulations. This is the first-ever insight obtained that overcomes the challenge of probing structure within very small volumes.
Their work opens the way to explore internal structures of soft nanoparticles that, in turn, will impact the design of new nanoparticles with well-defined luminescent characteristics. Highlights of their research include
- fully atomistic MD simulations with an innovative method to controllably collapse an inherently rigid polymer used to determine internal structure and stability of polydots made of dialkyl-paraphenylene ethynylene;
- nanoparticles remain predominantly spherical and compact in water, while their interface became significantly rough; and
- no internal correlations were observed between the aromatic rings on the polymer within the nanoparticle, consistent with the experimental luminescence of nanoparticles.
Work was performed at Clemson University and Sandia National Laboratories. The Clemson team acknowledges the support of DOE Basic Energy Sciences under contract DE-SC0007908.