Organogel is a class of hydrophobic soft polymer consisting of a large volume of liquid organic phase confined in a three-dimensional cross-linked polymer network. Organogels are the "twins" of hydrogels by such properties as swelling, adsorption properties, insolubility, viscoelasticity. The prospects of organogels can be explained by the additional functionality due to the huge variety of functional organic solvents. Despite the larger composition diversity and their great potential, organogels have not been applied as wide as hydrogels, mainly due to the lack of fabrication methods. The research of unique functionalities that organogels possess due to the variety of applicable liquid media, as well as the development of new convenient manufacturing methods, including 3D printing, remain limited. In this project, we aim to develop the fabrication of organogels via DLP printing and investigate their bulk and surface properties and applications.

The high solvent content organogels have been fabricated from lauryl acrylate ink via photopolymerization based 3D-printing and subsequent swelling in the various solvents. Swelling ratios are investigated in the hydrophobic solvents, such as medium-chain alcohols, toluene, mineral and fatty oils. The swollen organogels contain up to 90 weight percent of the organic liquid.

By switching the solvent immersed in the polymer network, the properties of the gel can be controlled. While a non-swollen polymer is possessing wet and solid adhesion, swollen 3D-printed organogels obtain hydrophobic slippery behaviour with the sliding angles of water droplets at near-zero tilting degrees. Non-adhesiveness of organogel to solids and liquids can be tuned by the choice of the solvent. The thermal stability of swollen organogels has been shown to be altered by the melting point of the dispersed liquid media and therefore is varied in the range from -30°C to more than 100°C.

Due to the hydrophobic nature and ability to confine organic solvents, organogels have been used as extraction vessels for the extraction of hydrophobic substances from aqueous solutions. DLP 3D printing allows simultaneous fabrication of hundreds of sphere extraction vessels with high surface area. This contributes to a higher contact area of the swollen non-polar solvent with the non-polar solute in the aqueous media. High hydrophobicity prevents interaction of the solvents and the gels after the extractions can be easily removed from the solution.

To conclude, a DLP-based 3D-printing fabrication method for organogel has been developed. Tunable properties of organogels combined with additive manufacturing open new horizons for the applications of these multifunctional materials as extraction, soft robotic, and multi-responsive polymers.