On the development of new poly(styrene-oxyethylene) graft copolymer resin supports for solid-phase organic synthesis

With the aim of creating new, improved solid supports for organic synthesis, a series of poly(styreneoxyethylene) graft copolymers 6a-d was synthesized by anionic polymerization of ethylene oxide from a polystyrene-supported 1,3-diol 5b. Graft lengths were varied from 29 to 58 repeat units (67-82 wt % polyoxyethylene). The so-formed alcohols 6a-d were further transformed into chlorides 7a-d, amines 8a-d, and two commonly used linkers, Wang 9a-d and HMPB 10a-d. These functional group interconversions were efficiently monitored using gel-phase C-13 NMR, and the solid-state properties of all copolymers were characterized by differential scanning calorimetry. Thermal properties of these materials were found to be dominated by the polyoxyethylene composition. A correlation between the melting point associated with the graft lengths and the physical properties of the resins was observed. The optimum graft copolymer composition, determined by balancing the degree of functional group loading with resin crystallinity and swelling, was found to be in the 0.4-0.5 mmol g(-1) range.