Morphology and Contact Angle Characterization of Deposited PE-PEO Diblock Copolymer on Silicon wafer

Abstract

Micro/nano-patterns of the diblock copolymer, PE-PEO, have been created to change and adjust the surface properties of a silicon wafer. Results show that the surface of pure silicon renders hydrophilic after thermal oxidation. Further treatment with alkoxyl silane coupling agent, the water contact angle becomes 130° and the oil one, 28°. The root-mean-square roughness, Rq, increases from sub-nanometer to 1.2 nm calculated using atomic force microscopy (AFM), indicating a high surface coverage of the coupling agent over the silica layer and the formation of covalent bonds. In addition, the hydrophilic PE-PEO coatings with thermal fused hydrophobic chains of the PE blocks and the alkyl tails of silane could be deposited by the dipping method and annealing. The modified surface gives a water contact angle of 110° and an oil one of 35°. Self-assembled striated patterns driven by heat have been found for the PE-PEO diblock copolymer coatings in the phase images of AFM.