Levich Institute Seminar – Tuesday, 12/13/2022

Tuesday, 12/13/2022
2:00 PM
Steinman Hall #124 (Exhibit Room)

Dr. Benjamin Ocko
Brookhaven National Labs

“Surface Freezing”

Simultaneous Zoom Link:  https://ccny.zoom.us/j/81100137769


Surface freezing (SF), the formation of a frozen interfacial monolayer in contact with its bulk liquid phase, is a property of simple chain molecules. These monolayers are among the simplest examples of self-assembly found in nature since they represent equilibrium behavior in a single component system. SF was first observed at the vapor interface of n-alkane molecules in 1992 for 16 <n< 50 using surface x-ray scattering and tensiometry methods [1]. The frozen monolayers consists of a rotator phase of densely packed molecules [2]. SF has also been observed for other alkyl terminated molecules including n-alkanols (long chain alcohols) and diols, for polymers, and for liquid metal alloys.  SF also occurs at solid/liquid [3] and liquid/liquid [4] interfaces. For bulk n-alkanols melts in contact with an oxide surface, the SF monolayer is also comprised of a densely packed layer that exist over a 10-30 deg C range. When melted, the monolayer has an unusual structure of a ”stretched liquid” where the molecules are significantly more extended than in the bulk liquid. This, and the SF behavior, are explained within a thermodynamic model combining interfacial hydrogen bonding and entropic effects. SF at the oil/liquid interface of surfactant-stabilized emulsion droplets was shown to induce a sequence of spherical-to-polyhedral droplet shape transitions, keeping the droplets liquid [5]. A temperature-driven self-emulsification of the droplets was also found. These and other related effects will be discussed in the talk.


[1] XZ Wu, EB Sirota, SK Sinha, BM Ocko, M Deutsch, PRL 70, 958 (1993)
[2] BM Ocko, XZ Wu, EB Sirota, SK Sinha, O Gang, M Deutsch, PRE 55, 3164 (1997)

[3] J Haddad et al, JPC 119, 17648 (2015)

[4] L Tamam et al., PNAS 108, 5522 (2011)

[5] S Guttman, Z Sapir, M Schultz, AV Butenko,B Ocko, M Deutsch, E Sloutskin, PNAS 113,   5522(2016)


We gratefully acknowledge the US Department of Energy/NSLS, grant AC02-98CH10886, and contributions from many colleagues over the years. A full list will be given in the talk.

  • Ph.D. 1984: Physics, MIT
  • B.A. 1978, Swarthmore College (Honors)
  • 2015-: Senior Physicist, NSLS II (BNL)
  • 2008-: Adjunct Professor, Department of Physics, SUNY Stony Brook
  • 2003-2015: Group Leader for Soft-Matter Physics in CMPMS (BNL)
  • 2002-2015: Senior Physicist (BNL)
  • 2001-2003:Soft Matter Thrust Leader, CFN, BNL
  • 1991-2002: Physicist, (BNL) 
  • 1988-1991: Associate Physicist (BNL)
  • 1987-1988: Assistant Physicist (BNL)
Soft-Matter Surface Physics, Surface X-ray Scattering, Liquid surfaces, molten salt surfaces, reverse osmosis water purification.
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