A novel approach addressing the classical deficiencies of molecularly imprinted polymers (MIPs), that is, low
binding capacity and nonuniform
binding sites, is reported. The thin walled
beads were produced in two steps
by first grafting thin MIP films, under controlled (RAFT) or noncontrolled conditions, from porous silica
beads following previously reported procedures. The resulting composites were compared in terms of film thickness, the grafted layer homogeneity, the effect of different support morphologies, and for their a
bility to recognize the template in chromatographic or static
binding tests. Thus, using
l-Phenylalanine anilide (L-PA) as template to imprint poly(MAA-co-EDMA) in such a way led to nanometer thick films where the resulting composite were a
ble to selectively retain the template in relation to the thickness of the grafted film. In the second step, removing the silica supports from the a
bove composites
by etching, led to nanometer thin walled
beads with structure, morphology and recognition properties strongly depending on grafting chemistry (RAFT or non-RAFT), monomer dilution and on the film thickness of the original composite. Thus whereas the thicker walled materials retained their mesoporous morphology and displayed enhanced enantioselectivity, load capacity, and higher surface areas compared to their composite precursors, the thin walled
beads showed lower surface areas indicating network collapse. The thin walled
beads prepared under dilute conditions in a
bsence of RAFT displayed a perfectly uniform
binding site distri
bution and a saturation capacity exceeding that of a conventional monolithic MIP. The
beads prepared
by RAFT control showed a further enhanced saturation capacity significantly exceeding that of the reference material. Finally, the reduced hydropho
bic character of the thin walled materials indicated the existence of two separate pore systems with different pore wetta
bilities.<
br>
Keywords:
bs.acs.org/action/doSearch?action=search&searchText=molecular+imprinting&qsSearchArea=searchText">molecular imprinting; bs.acs.org/action/doSearch?action=search&searchText=grafting&qsSearchArea=searchText">grafting; bs.acs.org/action/doSearch?action=search&searchText=surface+initiatied+polymerization&qsSearchArea=searchText">surface initiatied polymerization; bs.acs.org/action/doSearch?action=search&searchText=RAFT&qsSearchArea=searchText">RAFT; bs.acs.org/action/doSearch?action=search&searchText=template+synthesis&qsSearchArea=searchText">template synthesis; bs.acs.org/action/doSearch?action=search&searchText=isotherm&qsSearchArea=searchText">isotherm; bs.acs.org/action/doSearch?action=search&searchText=capacity&qsSearchArea=searchText">capacity