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Croll Group - Summer 2014

Left to Right : Bekele Gurmessa (Ph.D. - Physics), Damith Rozairo (Ph.D. Student - Materials and Nanotechnology),  Lance Johnson (Highschool Student), Tyler Anthony (Undergrad - Physics),  Andrew B. Croll (Boss).

Background: Bachellor Technology Center

Bekele Gurmessa


Degree Information:

Candidate for Ph.D., Physics.

M.Sc., Physics, Addis Ababa University, Ethiopia, 2007.

B.Ed., Physics, Haramaya University, Ethiopia, 2003.



Research Interests:

  • Mechanics of homo-polymer and block copolymer thin film instabilities: wrinkling, delamination, crumpling and folding
  • Response of block copolymer thin films' internal structure to surface instabilities
  • Buckling of colloidal particles: response of thin films made of non-continuum systems (particles) to mechanical deformation.


Current Research:

The goal of my research project is to investigate the residual stress of glassy and elastomeric polymer thin films using surface instabilities.  In particular, we are able to characterize the onset of plasticity of thin polymer films.  I am currently investigating how the domain structures formed when a block copolymer thin film is annealed above its glass transition temperature respond to similar thin film surface instabilities.

Damith Rozairo

Degree Information:

Candidate for Ph.D. Materials and Nanotechnology

B.Sc., Physics with a minor in mathematics, Minnesota State University Moorhead, 2009.





Current Research:

Damith is currently working on his dissertation which examines the physics of block copolymers in emulsion droplets. His work includes imaging microscopic to macroscopic scale emulsion droplets using a confocal microscope and exploits geometry to determine mechanical response (interfacial energies). His future goals consist of work with micropipette tensiometry and block copolymer double-emulsions.

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