Dynamical Threshold of Diluteness of Soft Colloids

Journal Article · Wed Jan 01 00:00:00 EST 2014 · ACS Macro Letters

OSTI ID:1185408

Chen, Wei-Ren ^[1]; Do, Changwoo ^[1]; Egami, T ^[2]; Falus, Peter ^[1]; Li, Xin ^[1]; Liu, Dazhi ^[1]; Porcar, L. ^[3]; Sanchez-Diaz, Luis E ^[1]; Smith, Gregory Scott ^[1]; Wu, Bin ^[1]

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1. ORNL
2. University of Tennessee, Knoxville (UTK)
3. National Institute of Standards and Technology (NIST)

The dynamics of soft colloids in solutions is characterized by internal collective motion as well as center-of-mass diffusion. Using neutron scattering we demonstrate that the competition between the relaxation processes associated with these two degrees of freedom results in strong dependence of dynamics and structure on colloid concentration, c, well below the overlap concentration c*. Triggered by the increasing inter-particle collisions, substantial structural dehydration and slowing-down of internal dynamics occurs before geometrically defined colloidal overlap develops. This observation is surprising since it is generally believed that the internal dynamics and conformation of soft colloidal particles essentially remain invariant below c*. The competition between these two relaxation processes gives rise to a new dynamically-defined dilute threshold concentration well below c*.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1185408
• Journal Information: ACS Macro Letters, Vol. 3, Issue 12
• Country of Publication: United States
• Language: English