Influence of polymerization temperature on the molecular recognition of imprinted polymers

This paper aimed at investigating the influence of polymerization temperature on the molecular recognition of molecularly imprinted polymers (MIPs) based on multiple non-covalent interactions. 3-l-Phenylalanylaminopyridine (3-l-PheNHPy) imprinted polymers were prepared using azobisnitriles as either thermal initiators or photoinitiators at various temperatures of 10, 40 and 60 °C, respectively. These polymers were subsequently evaluated in the high-performance liquid chromatographic (HPLC) mode for enantioselectivity. An unexpected result shows that polymer prepared at 40 °C has the highest enantioselectivity, but not the polymer prepared at lower temperature of 10 °C. Further, the effect of elution temperature and sample load on the selectivity of polymers was investigated in detail. In order to get a better understanding of the “exception”, the influence of polymerization temperature on the polymerization extent and polymer morphology was studied by FT-IR spectrum test, cross-polarization magic angle spinning (CP-MAS) 13C NMR spectra experiment and pore analysis. Based on these results we attribute this “exception” to that there is a tradeoff between the extent of polymerization and stabilization of the template–functional monomer complexes. And an optimal polymerization temperature can be found for each combination of template and monomer.