Perfluorophenylazide Photochemistry for Modification of Materials
Polymeric materials are proposed for applications in a variety of fields including and not limited to: biomedical applications, electronics, biosensor devices and water treatment. Covalent functionalization of these materials provides an effective means to adjust surface properties. These covalent approaches benefit more than noncovalent alternatives because they are more robust, creating stable attachment of groups with specific functional properties. Specifically, photoinitiated grafting can be performed under mild reaction conditions and low temperatures with high selectivity compared to other grafting techniques. Perfluorophenylazide (PFPA) chemistry has been used as a coupling agent for fluorinated phenylazide, which are capable of forming stable covalent bonds to sp2 or sp3 hybridized carbons or nitrogens. Phenylazides are popular because they are relatively simple to prepare, have fast kinetics, possess high reaction efficiencies, are easy to store and can covalently link organic or inorganic materials. We propose to synthesize PFPA polymers and small molecules to graft a variety of materials to enhance the materials surface properties. These materials include polymers, semiconductor surfaces, metals, carbons and metal oxide surfaces. The surface properties altered include increased hydrophilicity and conductivity, lowered surface roughness, and reactivity of the surface. We have successfully modified a variety of surfaces and enhanced specifically the rejection and fouling capability of water purification membranes and a variety of other materials. In conclusion, we were able to successfully synthesize a variety of polymers and small molecules for modification of water purification membranes.
The goals of this dissertation are to investigate perfluorophenylazide chemistry and its use in a variety of materials to create covalently bonded coatings to enhance materials properties. Chapter 1 provides an introduction, while Chapter 2 compiles detailed performance of a tetraaniline coating on ultrafiltration membranes with respect to anti-fouling properties. Chapter 3 briefly describes a project investigating the synthesis and properties of the octamer of aniline. Chapter 4 discusses a collaborative project in creating polymer coatings on nanofiltration membranes to enhance divalent ion rejection. In Chapter 5, ethyleneimine and sulfonates are coated onto polypropylene separators used in lithium-sulfur batteries to enhance the capacity of the batteries by preventing polysulfide migration. In Chapter 6, zwitterions are coated onto polydimethylsiloxane to prevent biofouling in biomedical devices.