Paper Number
SC14 

Session
Suspensions & Colloids

Title
Thermal processing of colloidal gels: Kinetics of quenching, coarsening and arrest

Presentation Date and Time
October 16, 2018 (Tuesday) 9:50

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

  1. Helgeson, Matthew E. (University of California, Santa Barbara)
  2. Nguyen, Tuan (University of California, Santa Barbara)
  3. Padmanabhan, Poornima (Rochester Institute of Technology)
  4. Zia, Roseanna N. (Stanford University, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Matthew E. Helgeson1, Tuan Nguyen1, Poornima Padmanabhan2, and Roseanna N. Zia3
1University of California, Santa Barbara, Santa Barbara, CA 93106; 2Rochester Institute of Technology, Rochester, NY; 3Chemical Engineering, Stanford University, Stanford, CA, CA 94305-4125

Speaker / Presenter 
Helgeson, Matthew E.

Text of Abstract
Colloidal suspensions exhibiting thermoresponsive interparticle attractions have opened up a vast new design space for the thermal processing of colloidal gels and glasses akin to centuries-old strategies in atomic and molecular materials, in which the controlled initiation and quenched arrest of phase instability can be used to tailor material properties. Here, we present initial steps toward exploring this space via a combination of experiments and large-scale dynamic simulations. Experiments comprise model colloidal suspensions containing thermoreversible bridging polymers which exhibit gelation concomitant with arrested phase separation by spinodal decomposition. The system is translated to detailed, parameter-matched dynamic simulations, where measurements of particle-level structure and dynamics provide complementary insights to experimental observations. Upon establishing the equilibrium fluid-fluid phase coexistence and non-equilibrium attractive glass transition for the system, we systematically study how the kinetics of spinodal coarsening and gelation depend on the details of the thermal quench taken – i.e., the depth and rate of temperature change into the arrested state within the region of phase coexistence. To demonstrate the utility of thermal processing, we show how these quench/anneal protocols can be used to modulate the linear and nonlinear rheological properties of arrested colloidal gels.