Thin film crystals of PLLA which is a kind of degradable plastics

These images show the ultra-thin films of low molecular weight PLLA (poly L-lactic acid). The left image shows the crystal morphologies of thick film, whereas the image on the right shows the crystal morphologies of thin film. The dendritic crystal structure was clearly observed with AFM (Atomic Force Microscope). Important information can be obtained on the crystal thickness, width, the growth method, and the dendrite size from these images. Moreover the process of crystal growth can even be recorded.
(Data provided by: Prof. Xu-Ming Xie, Department of Chemical Engineering, Tsinghua University)