UV initiated thiol-ene chemistry: A facile and modular synthetic methodology for the construction of functional 3D networks with tunable properties

Abstract

A facile methodology for the fabrication of functional crosslinked three dimensional (3D) networks has herein been explored via the benign and UV initiated thiol-ene coupling (TEC) chemistry. The careful selection of monomers or polymers and their feed ratio resulted in straightforward design of organic, inorganic and hydrogel networks with readily available alkenes or thiol functional groups. All crosslinked networks were fabricated within 1 second of UV exposure at wavelengths of 320-390 nm and generally exhibited excellent gel fractions around 90%. By introducing off-stoichiometric thiol and ene (OSTE) monomer feed ratios the window of mechanical properties could be manipulated. For the organic triazine system, the Young's modulus was altered from 780 MPa at an equimolar monomer ratio to soft 106 kPa for 2.5 equiv. with excess of thiol compared to enes. Postfunctionalizations with hydrophilic polyethylene glycols or acrylic acid and hydrophobic heneicosafluorododecyl acrylate were explored for the manipulation of functional networks. In this case, the rigid networks with excess of thiols were used as model substrates of which the initial contact angle (CA) of 60°was decreased to 43°by the introduction of acrylic acid and increased to 140°by successful attachment of fluorinated molecules. Finally, amalgamating micropatterning strategy with simple postfunctionalizations of hydrophobic groups resulted in superhydrophobic rigid surfaces with a CA of 173°. © The Royal Society of Chemistry.