Direct Visualization of Random Crystallization and Melting in Arrays of Nanometer-Size Polymer Crystals

Using tapping mode atomic force microscopy, we visualized in direct space and time resolved the changes in viscoelastic properties during crystallization and melting of polyethyleneoxide in 12 nm spheres of a block copolymer mesophase. All spheres crystallized individually and independently, randomly distributed sphere by sphere. Melting of the confined crystals also proceeded in a stochastic manner. Not all spheres melted at the same temperature, indicating different degrees of order of the individual nanometer-size polymer crystals. The independence of the spheres opens the possibility to manipulate material properties of surfaces at the nanometer scale.