Molecularly imprinted polymer films with binding properties enhanced by the reaction-induced phase separation of a sacrificial polymeric porogen

Molecularly imprinted polymers (MIPs) are synthetic materials that mimic the behavior of natural antibodies while exhibiting far greater stability than their natural counterparts. Although potentially very useful as recognition elements in chemical sensors, a major obstacle to their widespread application has been the difficulty in preparing MIPs in the thin-film format that is necessary for coupling them to interrogative transducers. This paper offers a solution to this problem by presenting a straightforward approach to the in situ synthesis of MIP films with good control of thickness and porosity. Spin coating is used to spread a pre-polymerization mixture, which is polymerized in situ with UV light. A key aspect of this process is the reaction-induced phase separation between the rapidly polymerizing acrylate monomers and a sacrificial linear polymer porogen. We studied the degree of phase separation and the ability of the films to rebind the target analyte as functions of the concentration and molecular weight of the polymer porogen, the volatility of the nonreactive solvent, and the spin rate used during polymerization. The current focus is on producing films with thicknesses ranging from approximately 1 micron to 10s of microns; however, the technique can easily be adapted to prepare films as thin as 10s of nanometers, enabling their use as recognition elements for a wide variety of chemical sensing platforms.