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Abstract:
High-field W-band (95 GHz) electron spin resonance spectroscopy of various spin probes was used to study the structure of highly cross-linked porous polymer resins based on a styrene- divinylbenzene matrix. The pores of these resins were created by template imprinting with reverse micelles solubilized in the mixture of monomers and cross-linkers prior to the polymerization. Functional groups in the resins were introduced by the use of polymerizable cosurfactants in the reverse micelles. Sufficiently large unpolar spin probes exhibit a distribution of mobilities that can be attributed to regions with different degrees of cross-linking in the polymer. The dynamics of a surfactant spin probe is sensitive to the presence of pores and the functionalization of the pore surface with highly polar groups. This effect disappears when the headgroup of the surfactant spin probe is esterified. It can be considered as a structural memory effect related to the use of reverse micelles as templates for imprinting. The result indicates that the pores can be filled or washed selectively.
