Morphology Phase Diagram of Ultrathin Anatase TiO_2 Films Templated by a Single PS-b-PEO Block Copolymer

摘要

Ultrathin TiO_2 films showing rich morphologies are prepared on Si(100) substrates using sol-gel chemistry coupled with an amphilic polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer as a structure-directing agent.The block copolymer undergoes a good-poor solvent pair induced phase separation in a mixed solution of 1,4-dioxane,concentrated hydrochloric acid (HCI),and titanium tetraisopropoxide (TTIP).By adjusting the weight fractions of 1,4-dioxane,HCI,and TTIP,inorganic block copolymer composite films containing a variety of different morphologies are obtained.On the basis of the results a ternary phase diagram of the morphologies is mapped.By calcination,anatase TiO_2 films are achieved.The morphologies and crystallographic phase of the films are studied with AFM,SEM,and XRD,respectively,and the formation mechanisms of the different morphologies are discussed.