Fabrication of superhydrophobic surfaces for self-cleaning application

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master_Oladosu_Ikeoluwapo_2025.pdf (2.64 MB)

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School of Chemical Engineering | Master's thesis
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Date

2025-11-03

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Chemistry

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Degree programme

Master's Programme in Chemical, Biochemical and Materials Engineering
Kemian-, bio- ja materiaalitekniikan maisteriohjelma
Magisterprogrammet i kemi-, bio- och materialteknik

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en

Pages

87

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Abstract

Contamination of surfaces such as solar panels and skyscrapers, through air pollution such as dirt or dust, is a major problem resulting in significant waste of money, labor, and energy for restoration. There is a need for a self-cleaning. Superhydrophobic surfaces were fabricated through a top-down fabrication approach, which includes optical lithography and replication molding. The fabrication process started with the design of micro/nano-scale structures using KLayout, followed by pattern transfer through a maskless aligner (MLA) to enable high-resolution structuring without the need for a physical mask. The pattern substrate undergoes plasma deposition for anti-adhesion coating, and finally, the substrate was replicated with PDMS molding for a self-cleaning experiment. To understand the effectiveness of the structured surfaces, their ability to repel water and self-cleaning performance were compared with plain, unstructured PDMS. The experiments were carried out by spreading contaminant (DMT Test Dust A2 fine quartz-free) on a surface, followed by 100µL of water droplets being dropped on the contaminated surface six consecutive times on the same spot, making a total volume of 600µL of water droplets. The rolling motion of water droplets facilitated the removal of the contaminant. This was captured and further analyzed with ImageJ software. The results show that the patterned PDMS structure (honeycomb) exhibits 99% self-cleaning efficiency at a 30º tilting angle, whereas the unstructured PDMS achieves only 29% self-cleaning efficiency under the same conditions. The results confirmed strong self-cleaning capability of the fabricated surfaces.

Description

Supervisor

Franssila, Sami

Thesis advisor

Jokinen, Ville

Keywords

superhydrophobic, self-cleaning, maskless aligner (MLA), polydimethylsiloxane (PDMS), polymer replication, wetting

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https://urn.fi/URN:NBN:fi:aalto-202512179393

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[dipl] Kemian tekniikan korkeakoulu / CHEM