Polymeric monolithic materials: Syntheses, properties, functionalization and applications

The synthetic particularities for the synthesis of polymer-based monolithic materials are summarized. In this context, monoliths prepared via thermal-, UV- or electron-beam triggered free radical polymerization, controlled TEMPO-mediated radical polymerization, polyaddition, polycondensation as well as living ring-opening metathesis polymerization (ROMP) will be covered. Particular attention is devoted to the aspects of controlling pore sizes, pore volumes and pore size distributions as well as functionalization of these supports. Finally, selected, recent applications in separation science, (bio-) catalysis and chip technology will be summarized. © 2007 Elsevier Ltd. All rights reserved

Terpyridinebased silica supports prepared by ring-opening methathesis polymerization for the selective extraction of noble metals

The synthesis of a terpyridine-based sorbent for solid-phase extraction (SPE) of noble metal ions is described. For this purpose, 4'-(norborn-2-en-5-ylmethylenoxy)terpyridine was copolymerized with norborn-2-ene via Mo(N-2,6-i-Pr2-C6H3)(=CHCMe2Ph)(OC(CH3)(CF3)2)2-catalyzed ring-opening metathesis polymerization (ROMP) to give a poly(norbornene900-b-4'-(norborn-2-en-5-ylmethylenoxy)terpyridine60) block-copolymer. This block-copolymer was used for the preparation of polymer-coated silica 60 (4.8 wt.% coating), which was investigated for its extraction capabilities for Cr(III), Mn(II), Re(II), Fe(III), Ru(III), Co(II), Rh(III), Ir(III), Ni(II), Pd(II), Pt(II), Cu(II), Ag(I), Au(III), Zn(II), Cd(II) and Hg(II), at different pH. Under competitive conditions and at pH Re > Ir > Rh > Ru > Fe > Cr ˜ Mn ˜ Cd ˜ Zn. Enhanced selectivity was observed at pH = 3.5, the order was Au > Hg > Pd ˜ Ag > Rh > Pt > Ir ˜ Re > Cu > Co ˜ Zn ˜ Cd ˜ Ni > Cr > Mn. The maximum metal loading that was achieved under non-competitive conditions was >6 mg/g for Au(III), Hg(II), Pd(II) and Ag(I). Even under competitive conditions, loadings of >6 mg/g were realized for Au(III) and Hg(II). Quantitative recoveries >97% were observed for all metals in case loading was stopped before reaching the point of breakthrough

Synthesis of water-soluble homo- and block-copolymers by RAFT polymerization under gamma-irradiation in aqueous media

The ambient temperature (20 degrees C) reversible addition fragmentation chain transfer (RAFT) polymerization of several water-soluble monomers conducted directly in aqueous media under gamma-initiation (at dose rates of 30 Gy h(-1)) proceeds in a controlled fashion. Using functional trithiocarbonates, i e.. S,S-bis(alpha,alpha'-dimethyl-alpha ''-acetic acid) trithiocarbonate (TRITT), 3-benzylsulfanyl thiocarbonylsulfanyl propionic acid (BPATT). and dithioester, i e, 4-cyanopentanoic acid dithiobenzoate (CPADB), as chain transfer agents, fully water-soluble polymers of monomers such as N,N-dimethylacrylamide, 2-hydroxyethyl acrylate, acrylamide or oligo(ethylene glycol) methacrylate and stimuli-responsive polymers of monomers such as acrylic acid. N-isopropylacrylamide, 2-(dimethylamino)ethyl methacrylate or 2-acrylamido-2-methylpropane sulfonic acid can be obtained over a wide range of degrees of polymerization up to 10,000 with low polydispersity (typically (M) over bar (w)/(M) over bar (n) < 1 2) to near quantitative conversions Well-defined block copolymers between these monomers, based on several asymmetric macro-RAM agents, can be obtained, suggesting that the RAFT agents are stable throughout the polymerization process so that complex and well-defined architectures can be obtained