24 research outputs found
Controlling the surface chemistry and chromatographic properties of methacrylate-ester-based monolithic capillary columns via photografting
Preparation of monolithic capillary columns for separations in the CEC mode using
UV-initiated polymerization of the plain monolith followed by functionalization of
its pore surface by photografting has been studied. The first step enabled the preparation
of generic poly(butyl methacrylate-co-ethylene dimethacrylate) monoliths
with optimized porous properties, controlled by the percentages of porogens 1-
decanol and cyclohexanol in the polymerization mixture, irradiation time, and UV
light intensity. Ionizable monomers [2-(methacryloyloxy)ethyl]trimethylammonium
chloride or 2-acryloamido-2-methyl-1-propanesulfonic acid were then photografted
onto the monolithic matrix, allowing us to control the direction of the EOF in CEC.
Different strategies were applied to control the grafting density and, thereby, the
magnitude of the EOF. To control the hydrophobic properties, two approaches were
tested: (i) cografting of a mixture of the ionizable and hydrophobic monomers and
(ii) sequential grafting of the ionizable and hydrophobic monomers. Cografting
resulted in similar retention but higher EOF. With sequential grafting, more than
50% increase in retention factors was obtained and a slight decrease in EOF was
observed due to shielding of the ionizable moieties
NEW CHROMOPHORES CONTAINING SULFONAMIDE, SULFONATE, OR SULFOXIMIDE GROUPS FOR 2ND-HARMONIC GENERATION
BEECHER JE, DURST T, FRECHET JMJ, et al. NEW CHROMOPHORES CONTAINING SULFONAMIDE, SULFONATE, OR SULFOXIMIDE GROUPS FOR 2ND-HARMONIC GENERATION. ADVANCED MATERIALS. 1993;5(9):632-634