Investigating resins for solid phase organic synthesis: The relationship between swelling and microenvironment as probed by EPR and fluorescence spectroscopy

The relationship between observed swelling of two cross-linked polystyrene resins and the microenvironment within polymer matrixes has been examined. Polystyrene cross-linked with either divinyl benzene (Merrifield resin) or 1,4-bis(4-vinylphenoxy)butane (JandaJel) was investigated with fluorescence and electron-paramagnetic resonance spectroscopy. Fluorescence spectroscop y revealed a superior correlation between observed swelling and solvation e ffects using a dansyl probe with JandaJel than with Merrifield resin. Howev er, the internal viscosity of pre-swollen JandJel is higher than Merrifield resin, as determined by EPR measurements. The combination of these two ana lytical methods provides insights into the physical differences observed be tween these two chemically similar resins and suggests caution should be us ed if using singular physical techniques to probe the microenvironment of p olymeric matrixes.