We have investigated the cause of catalyst deactivation observed during surface-confined atom-transfer radical polymerization of acidic monomers. Surface-tethered polyelectrolyte layers of poly(itaconic acid) and poly(methacrylic acid) were grown from self-assembled initiator monolayers of 2-bromoisobutyryl bromide terminated thiol molecules. This polymerization initiator molecule and a copper-based organometallic catalyst allowed tethered polyelectrolyte chains to be grown directly via radical polymerization at room temperature in aqueous solutions. Structural and surface properties of the layers were characterized using phase-modulated ellipsometry and external-reflection Fourier transform infrared spectroscopy. Catalyst deactivation due to generation of a coordination complex between the deprotonated acid monomers and copper catalyst during the polymerization process appears to be an important cause of chain growth cessation. Surface-initiated polymerizations performed after aging of the catalyst-containing deprotonated monomer solution revealed inhibition of polymer growth with increasing aging times. This suggests that catalyst is consumed over time by complexation with carboxylate groups of the monomer and dissociation and disproportionation in water.

The direct polymerization of deprotonated acidic monomers in aqueous solutions was achieved via surface-confined atom transfer radical polymerization (SC-ATRP) to produce surface-tethered polyelectrolyte brushes. Layers of poly(itaconic acid), poly(methacrylic acid), and sodium poly(styrene sulfonate) were grown by SC-ATRP from self-assembled initiator monolayers of [BrC(CH 3 ) 2 COO(CH 2 ) 11 S] 2 on gold substrates. The polymer layers were characterized with variable-angle ellipsometry and external-reflection Fourier transform infrared spectroscopy. Without intervention, atom transfer radical polymerization catalysts were deactivated by complexation with the deprotonated acidic monomers, disproportionation, and dissociation during the polymerization of these monomers in water; the result was the cessation of polymer growth. The addition of an alkali salt to the reaction media suppressed catalyst deactivation, allowing polymer layers to increase in thickness linearly for longer periods of time with respect to salt-free conditions. This result suggested an improved degree of polymerization control. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 566-575, 2007

Combining inkjet printing and atom-transfer radical polymerization (ATRP) provides a straightforward and versatile method for producing patterned polymer surfaces that may serve as platforms for a variety of applications. We report the use of drop-on-demand technology to print binary chemical gradients and simple patterns onto solid substrates and, by using surface-confined ATRP, amplify these patterns and gradients. Chemically graded monolayers prepared by inkjet printing dodecanethiol and backfilling with 11-mercaptoundecanol showed continuous changes in the water contact angle along the gradient. These samples also exhibited a distinct change in the intensity of methyl group and C-O stretching modes along the gradient. Graded or patterned polymer layers were produced by growing, with ATRP, tethered poly(methyl methacrylate) (PMMA) layers from gradient or patterned printed monolayers that contained a bromo-capped initiator. Atomic force microscopy and optical microscopy confirmed that the PMMA layers amplified the underlying printed initiator layer with remarkable fidelity.

A new semi-fluorinated perfluorocyclobutyl (PFCB) aryl ether containing polymer was prepared in high yield via the condensation of a commercial 4,4 1 -((1,2,3,3,4,4-hexafluorocyclobutane-1,2-diyl)bis(oxy))bisphenol (bisphenol T) and bis(trifluorovinyloxyether)biphenyl producing transparent, flexible films. The polymer system was structurally characterized using 1 H and 19 F NMR and exhibited a high degree of thermal stability as determined by thermogravimetric analysis capacity. The sulfonated analogue showed the highest degree of sulfonation at 27% from ion-exchange chromatography, producing a conductivity of 0.011 S cm 21 at 100% relative humidity.

Poly(itaconic acid) (PIA) was grown from surface-tethered initiator sites via atom transfer radical polymerization (ATRP). The surface-tethered PIA layers were grown from hydroxyl-terminated SAMs capped with initiator molecules of 4-(chloromethyl)-benzoylchloride. This polymerization initiator molecule and a copper-based organometallic catalyst allowed tethered PIA chains to be grown via ATRP at room temperature in aqueous solutions. Ellipsometric studies and external-reflection, Fourier-transform infrared spectroscopy (ER-FTIR) confirm the presence and growth of the surface-tethered PIA layer. We describe here how changing the temperature of polymerization alters the layer growth and kinetics of the process, and demonstrate, via ER-FTIR spectroscopy, that these surface-tethered layers do bind cationic dyes through ion-exchange mechanisms.