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Intern: Ursula Koniges, Chemical Engineering & Biochemistry, University of Washington Mentor: Hongbo Zeng Faculty Supervisor: Jacob Israelachvili Department: Chemical Engineering

HYDROPHILIC AND HYDROPHOBIC MATERIAL SURFACE MODIFICATIONS

Many commonly used polymers, such as polystyrene (PS) and polydimethylsiloxane (PDMS), are hydrophobic and thus not ideal for applications which benefit from hydrophilic material surface properties (such as biomaterials or micro fluidic devices). Conversely, mica is hydrophilic and not ideal for applications which benefit from hydrophobic surface properties. Means of altering the surface hydrophobicity of materials while maintaining bulk properties exist. This investigation concerns the surface modification of PS, PDMS, and mica via introduction of hydrophilic or hydrophobic functional groups to material surfaces. PS and PDMS are modified to increase surface hydrophilicity. Mica is modified to increase surface hydrophobicity. Introduction of hydrophilic functional groups is accomplished via UV-ozone treatment. Introduction of hydrophobic functional groups is accomplished via [3- Aminopropyl]triethoxysilane (APTES) solution immersion. The resulting surface energy effects are examined using sessile drop contact angle analysis. Surface forces apparatus (SFA) is used to measure deposited APTES monolayer thickness. Results indicate successful achievement of desired surface modifications.

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