Journal of Polymer Science Part A: Polymer Chemistry, Vol.43, No.11, 2348-2357, 2005
Preparation of chiral polystyrene monoliths by utilizing W/O emulsion polymerization and their optical resolution ability
We synthesized two kinds of chiral polystyrene-based monoliths, which are macroporous gel with continuous open-celled monolith structure. Thus, two chiral styrene monomers, (-)-p-[dimethyl(10-pinanyl)silyl] styrene ((-)-PSSt) and (-)-p-(menthoxycarbonyl)styrene ((-)-MtSt]), were prepared and subjected to water-in-oil emulsion polymerization in the presence of divinylbenzene and AIBN. The macroporous structure of the obtained monoliths was directly confirmed by SEM observation. The obtained monoliths showed an optical resolution ability. That is, in the enantioselective adsorption using trans-stilbene oxide, poly[(-)-PSSt] monolith and poly[(-)-MtSt] monoliths preferentially adsorbed (SS)-isomer [poly[(-)-PSStl monolith: α((S,S)) = 1.49 (0.25 wt % acetone solution); poly[(-)-MtSt] monolith: α((S,S)) = 1.39 (0.25 wt % toluene solution)]. Depinanylsilylation of the poly[(-)-PSStl monolith and removal of menthyl groups from the poly[(-)-MtSt] monolith were achieved by acid-catalyzed. scission of the Si-C bond and base-catalyzed hydrolysis, respectively. In addition, de-poly[(-)-PSSt] and de-poly[(-)-MtSt] showed enantioselectivity ((SS)-isomer preferentially absorbed) in adsorption using trans-stilbene oxide in spite of the absence of chiral substituents in the monoliths. © 2005 Wiley Periodicals, Inc.
Keywords:chiral polystyrene;depinanylsilylation;enantioselective adsorption;monolith;optical resolution;porous material