The Fabrication And Morphology Of Polymer P3HT And PEO Micro-nano Structure Films Under Restricted Conditions

The fabrication of polymer micro-nanostructure film has always been a hot issue in the field of polymer materials.How to simply and effectively prepare a polymer micro-nanostructure film with high regularity,high fidelity,and high replication ratio remains a thorny issue.We demonstrated that the poly(3-hexylthiophene)(P3HT)nanograting topography can be excellently fabricatedthe via vaporassisted room-temperature nanoimprinting lithography(VART-NIL)technique based on a poly(dimethylsiloxane)(PDMS)mold and vapor atmosphere.And hot embossing technology by PDMS mold(HET)is being investigated as one of the promising methods to fabricate the polymer micro-nanostructure films of poly(ethylene oxide)(PEO).The VART-NIL and HET method can mainly able to copy the pattern structure defined on a template into a polymer thin film.The main reason is that PDMS mold have the advantages of strong chemical stability,low surface energy,and favorable heat conductivity.The method of fabricating polymer micro-nanostructure films based on PDMS mold is of great significance to the processing of semiconductor material devices,and the crystallization behavior and crystallization mechanism of the polymers under micro-nanoconstrained conditions are worth further investigation.In this dissertation,the conjugated polymer P3 HT patterned film was fabricated by VART-NIL,and the patterned film and PDMS mold morphology were studied by atomic force microscope(AFM)and scanning electron microscope(SEM).Experiments demonstrate that the P3 HT patterned film completely replicates the mould information,and the nanostructure fabricated are regular and not collapse.When the morphology of P3 HT crystals was investigated experimentally,it was found that a large number of rod-like crystals were present in the P3 HT patterned films??assisted by carbon disulfide and chlorobenzene vapors.Furthermore,the molecules and crystal orientation arrangements of P3 HT patterned films were investigated using Shanghai Synchrotron Radiation Facility with grazing incidence wide angle X-ray diffraction(GIWAXD).It was illustrated that the VART-NIL method based on a PDMS mold could be employed to fabricate a patterned nanograting topography structure successfully and this technique was able to possess a high replication fidelity for the polymer pattern.The VART-NIL procedure was able to induce the molecular alignment transition from an edge-on to face-on alignment,including both the face-on conformation of form I and form II crystals.However,for the nanoimprinted P3 HT nanograting film,there were both edge-on and face-on molecular alignments of form II and form I crystals for the P3 HT nanograting film.The edge-on molecule alignment of form II and form I crystals may mainly result from the effect of the residual layer beneath the nanograting pattern.And the face-on molecule alignment of form II and form I crystals may mainly induce the molecular alignment transition from an edge-on to face-on alignment.The thermal annealing treatment has a different effect on the stability of the nanopatterned surface and molecular alignment.The crystallographic transition of form II to form I was investigated during the elevated temperature process.However,the nanoimprint-induced face-on molecular alignment of the nanograting film was only retained and the diffraction signal has been enhanced in the form I conformation after the cooling temperature process.It was interesting that the relatively uniform and regular nanograting profile could not be found at 150 o C and there was an obvious distortion or deformation towards a planar surface,and nanostructure do not return to their pre-thermal annealed morphology when returned to room temperature.The patterned film of polymer PEO was fabricated by HET,and the patterned film and PDMS mold morphology were characterized by the tapping mode of AFM.It demonstrate that the patterned film has a large area,the micro-nanostructure of pattterned films is not collapsed,and the PEO crystal has a high bulk density and can accurately replicate template information.We explore the morphology of PEO micro-nanostructured films at different concentrations.Experiments show that whenthe concentration of PEO is high,the residual layer of PEO micro-nanostructure films is too thick,which will directly affect the limited crystallization of PEO crystals in micro-nanostructure.Conversely,the concentration of PEO is low can not be fully reproduced the template information,only the appropriate concentration of PEO can fabricate a suitable micro-nanostructured film.The polymer of P3 HT patterned film was fabricated by VART-NIL,the P3 HT molecules and crystal orientation arrangements have been successfully induced to change from edge-on to face-on.The deeper research and understanding of P3 HT molecules and crystal orientation arrangements provide new ideas and guidance for the application and processing of semiconductor devices in the future.In addition,the advantages of hot embossing technology based on PDMS template in fabricating polymer micro-nanostructural thin films were explored.