Stable jets of viscoelastic fluids and self-assembled cylindrical capsules by hydrodynamic focusing

We demonstrate formation of long-lived cylindrical jets of a viscoelastic fluid using hydrodynamic focusing. A solution of polyacrylamide in water is driven coaxially with immiscible oil and subjected to strong extensional flow. At high flow rates, the aqueous phase forms jets that are 4-90 mu m in diameter and several centimeters long. The liquid surfaces of these jets are then used as templates for assembly of microspheres into novel rigid and hollow cylinders.