Paper Number
PO104 

Session
Poster Session

Title
Dynamics of polymer-grafted nanoparticles controlled by soft confinement

Presentation Date and Time
October 17, 2018 (Wednesday) 6:30

Track / Room
Poster Session / Woodway II/III

Authors (Click on name to view author profile)

  1. Slim, Ali (University of Houston, Chemical and Biomolecular Engineering)
  2. Poling-Skutvik, Ryan (University of Houston, Chemical and Biomolecular Engineering)
  3. Conrad, Jacinta C. (University of Houston, Chemical and Biomolecular Engineering)
  4. Krishnamoorti, Ramanan (University of Houston, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Ali Slim, Ryan Poling-Skutvik, Jacinta C. Conrad, and Ramanan Krishnamoorti
Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204

Speaker / Presenter 
Slim, Ali

Text of Abstract

Polymer-grafted nanoparticles (PGNPs) can enhance the properties of composites and improve the biocompatibility of targeted drug delivery. Improved understanding of the structure and dynamics of these materials is key to advancing their performance in applications. There are three size regimes of interest when studying PGNPs. When the radius of gyration Rg of grafted polymer is much smaller than NP radius RNP, dynamics of PGNPs are expected to be similar to those of hard spheres. Conversely, when Rg is much larger than RNP, PGNPs behave like dendritic or star polymers. In the intermediate regime where Rg and RNP are comparable, the structure and dynamics become influenced by both the hard (NP-NP) and soft (polymer-polymer) interactions. This regime is not well understood.

Using a “grafting-to” procedure, we graft high molecular weight polystyrene (Mw = 355 kDa, Rg = 21 nm) on spherical silica nanoparticles (RNP = 24 nm) and disperse these PGNPs in solutions of free linear polystyrene of molecular weight 150, 590, and 1100 kDa in 2-butanone. We characterize the structure and dynamics of this system using neutron and x-ray scattering, respectively. The grafted polymer chains are compressed in the presence of free polystyrene due to an increase in osmotic pressure of the solutions. The dynamics of PGNPs decouple from bulk viscosity and deviate from the behavior predicted for hard spheres. These results suggest that the grafted polymer introduces soft interactions between the nanoparticles and free polymers that generate deviations from the expected behavior.