Hierarchical polystyrene patterns produced by electrospinning

When a 25 wt% polystyrene solution was electrospun at relatively low applied voltage, the bending instability initiated, grew and disappeared, repeatedly. Upon further lowering of the applied voltage, the bending instability died immediately after it started and only a straight electrified jet was observed. By manipulating the bending instability of the jet, uniform polystyrene hierarchical patterns were produced by a buckling process.The observed buckling patterns are similar to those of a gravity-driven jet. The conditions for producing buckled polystyrene patterns are reproducible. These small scale buckled polymer patterns can be made very long and uniform. The size of the buckling coil was adjusted by changing the distance between tip and collector. Different large scale patterns, that consist of tiny buckled polymer patterns, can be written by a programmed machine. Fluffy fiber balls, composed of buckling coils, were produced.