The fabrication and molecular alignment of poly(ethylene oxide) grating film based on hot embossing technology

Hot embossing technology, regarded as one of the most promising and cost-effective methods to fabricate high-precision and high-quality patterns at micrometer or nanometer scales, has been attracting more attention. In our demonstration here, we mainly employ a hot embossing technique based on a poly(dimethylsiloxane) (PDMS) template to fabricate a grating pattern structure for a polymer poly(ethylene oxide) (PEO) thin film. The hot embossing process mainly consists of the preparation of a pristine film, embossing under a suitable heating temperature and pressure, and demolding the template from the embossing system. A uniform, regular and periodic topographical grating morphology has been obtained on the surface of a polymer PEO film of obvious use for a large area. Grazing incidence wide angle X-ray diffraction (GIWAXD) is employed to illustrate that hot embossing technology is able not only to successfully fabricate the topographical grating structures of a PEO grating thin film, but also interestingly to induce the formation of a highly oriented flat-on lamellar alignment or molecular alignment structure inside the grating pattern structure of a PEO grating film. A tilt orientation mode is identified for the pristine PEO film; however, it is striking to find that a flat-on orientation is induced for the PEO grating film by the hot embossing process. Furthermore, there is miraculously only a flat-on orientation within the grating film and the highly oriented flat-on lamellar alignment can be achieved at various temperatures.