Patterning of Alkanethiols Using the Nanotrench Template

The PMMA trench patterns (300 nm wide with 700 nm spacing) with different geometries were created on a gold substrate as follows. A 120 nm thick Au layer was evaporated onto a Si (100) wafer with 5 nm thick Cr as an adhesion layer. The PMMA resist with 150 nm thickness was spin-coated onto the Au substrate. EBL was used to write previously programmed patterns on the PMMA film. The exposed PMMA regions were developed using methyl isobutyl ketone solution and then treated by oxygen plasma for 5 seconds to remove the residual PMMA resist at the bottom of the PMMA trench. 

After the template with PMMA pattern was cleaned by oxygen plasma, it was immersed into mM MUAM, or HUT or MUDA in ethanol for 24 hours to form well-ordered hydrophilic self-assembled monolayers (SAMs) in the PMMA trench area. Then, the template with assembled SAMs was washed by ethanol several times to remove the multiple thiol layers on the top of the SAMs on the surface. Afterwards, the template was extracted by acetone with a Soxhlet extractor for 24 hours to completely remove the remaining PMMA resist in the second area. Finally, the template was immersed into mM ODT in ethanol for 24 hours to grow the well-ordered hydrophobic alkanethiols on the remaining gold area (i.e., the spacing area of the original PMMA pattern). 

2 Patterning of Polystyrene/Poly(acrylic acid) Blends on Nanotrench Template 

Once the secondary thiol treatment was finished, the chemically patterned template was immediately put on the rotating plate of a spin coater (Specialty Coatings Systems G3P-8) prefilled with high purity nitrogen gas and a droplet of polymer solution, such as 1 wt% PS in DMF, 1 wt% PAA in DMF, or 1 wt% PS/PAA with 70/30 ratio in DMF, was placed on the top of the pattern area of the template. After remaining quiescent for 5 minutes, the polymer solution was spin-coated on the template surface with 3000 rpm 

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