Ethyl acetate hydrophobic bonding

While there are other solvents that may also be used effectively with reversed-phase sorbents, these solvents are capable of dissolving the range of compounds that are generally isolated by SPE. If more hydrophobic solvents are used in bonded-phase SPE, then the sorbent must be carefully dried by vacuum to remove all traces of water in the silica matrix in order that the eluting solvent can interact with all areas of the sorbent and not be stopped by residual water trapped in the pores. If this is not done, then the hydrophobic solvent (let us say, methylene chloride) will not effectively wet the surfaces of the C-18 bonded phase and poor recoveries will result. If methanol, acetonitrile, or ethyl acetate is used, then complete drying of the sorbent is not required because the solvent will either be miscible with water (methanol and acetonitrile) or displace the water from the silica (ethyl acetate). 

Poly(Propylene Fumarate) (PPF) is a linear, unsaturated, hydrophobic polyester (Structure 12) containing hydrolyzable ester bonds along its backbone. PPF is highly viscous at room temperature and is soluble in chloroform, methylene chloride, tetrahydrofuran, acetone, alcohol, and ethyl acetate [66]. The double bonds of PPF can form chemical crosslinks with various monomers, such as W-vinyl pyrrolidone, poly(ethylene glycol)-dimethacrylate, PPF-diacrylate (PPF-DA), and diethyl fumarate [67,68]. The choice of monomer and radical initiator directly influence the degradative and mechanical properties of the crosslinked polymer. Once crosslinked, PPF forms a solid material with mechanical properties suitable for a range of bone engineering applications. 

---