Hydrophilic polymer supports for solid-phase synthesis: hydroxyl-functional beads of poly(vinylpyrrolidone)

Poly(vinylpyrrolidone) (PVP) has solubility properties that make it an attractive material for polymer-assisted synthesis applications; however, the naked polymer lacks reactive groups upon which to do chemistry. Furthermore, large differences in radical reactivity between 1-vinylpyrrolidin-2-one (NVP) and most other monomers lead to compositional drift during copolymerization, further complicating the introduction of functional groups into the polymer using this method. Monomers that are derivatives of NVP itself are expected to show smaller differences in radical reactivity and therefore provide a way of preparing PVP with adjustable properties. Three monomers introducing hydroxyl-functional groups and a new cross-linker, all derivatives of NVP, were synthesized and used in the preparation of a new type of hydrophilic polymer beads by aqueous suspension polymerization. These lightly cross-linked beads contain hydroxyl groups at a functional loading of 0.21-0.29 mmol/g and swell extensively in a broad range of solvents.