Title
Unusual polymer dynamics in 2D.
Abstract: 
Many synthetic polymers and unfolded proteins can be spread on the surface 
of a liquid, to form a monolayer film. In this geometry, confined to a 
two-dimensional space, molecules have very different structural and flow 
properties compared to those usual in bulk solutions. The mechanical 
properties of monolayers are studied by surface rheology. This topic will be 
reviewed, including some new developments in experimental techniques. The 
talk will focus on experiments conducted at various surface packing 
fractions, highlighting regions where various different molecules show 
universal behavior. At low concentrations the layers are in thermodynamic 
equilibrium in a fluid phase, and their dynamics can be understood as 
arising from the 2D molecular chain nature. Upon increasing the 
concentration there is a transition to a soft-solid "jammed" state. Here 
viscoelastic data at different frequencies and concentrations can be 
superposed, via a time-concentration superposition that is still not fully 
understood.