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The performance of catalyst transfer polymerization (CTP) reactions which depend on catalyst association was studied on 3,6-dioctylthiothieno[3,2-b]thiophene (TT) monomers. This monomer was selected because a strong association of the catalyst is expected, since the aromaticity of thienothiophene is largely maintained when the catalyst and thienothiophene associate. This study includes both reported and unreported Ni- and Pd-catalyst systems. It is found that no polymer formation can be observed using Ni-catalysts, whereas Pd-catalysts show a similar behavior as for other monomer systems. During the study of the Ni-catalyzed CTPs, the π-associated Ni0-complex has been isolated in situ and displayed a high stability in solution. It is shown that the associated complex interferes with the polymerization reaction and even prevents polymer formation. Furthermore, this complex prevented any Kumada-coupling reaction in the presence of the TT unit, as it serves as a “trapping site” for free Ni0 catalyst entities. Ni0-trapping 2 does not occur during polymerization of 3-alkylthiophene, confirming the presence of the π-associated Ni0-complex in this polymerization. This introduces a new convenient method of probing Ni0-association during all Ni-catalyzed reactions. Furthermore, these results establish the presence of an upper limit to the catalyst association strength -above which oxidative addition is prevented and the polymerization is inhibited- and they therefore add extra considerations for optimal catalyst design. ispartof: Macromolecules vol:47 issue:24 pages:8548-8555 status: published

The formation in solution of a supramolecular graft copolymer bearing conjugated blocks is demonstrated using diffusion ordered NMR spectroscopy (DOSY). A tailor-made poly(3-(2-ethylhexyl)thiophene) (P3EHT) with a phenol end group is synthesized. For this purpose, the chain-growth mechanism of the polymerization of 2-bromo-5-chloromagnesio-3-alkylthiophenes in the presence of a Ni(dppp) catalyst (dppp = 1,3-bis(triphenylphosphino)propane) is exploited, as it enables the use of functionalized initiators to introduce specific end groups. The so-obtained polythiophene was subsequently mixed in solution with poly(4-vinylpyridine) (P4VP) to enable phenol-pyridine hydrogen bonding. The formation of the supramolecular graft copolymer is studied using DOSY-measurements. Based on the results thereof, the amount of P3EHT attached to the P4VP is calculated and the association constant of the hydrogen bond is estimated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 804–809

This paper presents the synthesis and characterization of low-bandgap materials based on cyclopenta[1,2-b;3,4-b′]dithiophene (CPDT). An array of electron-poor monomers is synthesized and used to prepare homo- and alternating donor–acceptor copolymers. This yields polymers with low bandgaps (Eg = 1.12–1.23 eV) and broad light absorption (400–1100 nm). The influence of the electron-withdrawing substituent and the donor material on the polymer properties is studied. It is demonstrated that the low bandgap is not a result of intramolecular charge transfer, but of a transition localized in the electron-poor CPDT monomer. The bandgap can be correlated with the substituent on the CPDT monomer and is relatively independent of other parameters, resulting in materials with an easily tunable bandgap.

Ever since iron oxide nanoparticles have been recognized as promising scaffolds for biomedical applications, their surface functionalization has become even more important. We report the synthesis of a novel polyethylene glycol-based ligand that combines multiple advantageous properties for these applications. The ligand is covalently bound to the surface via a siloxane group, while its polyethylene glycol backbone significantly improves the colloidal stability of the particle in complex environments. End-capping the molecule with a carboxylic acid introduces a variety of coupling chemistry possibilities. In this study an antibody targeting plasminogen activator inhibitor-1 was coupled to the surface and its presence and binding activity was assessed by enzyme-linked immunosorbent assay and surface plasmon resonance experiments. The results indicate that the ligand has high potential towards biomedical applications where colloidal stability and advanced functionality is crucial. ispartof: PLoS One vol:9 issue:10 ispartof: location:United States status: published

In this manuscript, the Kumada catalyst transfer polymerization (KCTP) of cyclopenta[2,1-b;3,4-b′]dithiophene (CPDT), a monomer consisting of two fused thiophene entities, is investigated. It is shown that this polymerization follows a controlled chain-growth mechanism. Furthermore, the formation of block copolymers with poly(3-alkylthiophene)s is investigated, and it is shown that these block copolymers can be formed if 3-alkylthiophene is used as the first block and CPDT as the second. The resulting all-conjugated block copolymers consist of two blocks with substantially different electronic and physical properties and it is shown that the blocks influence each other, resulting in a unique material with different properties compared to a blend. © 2013 American Chemical Society. ispartof: Macromolecules vol:46 issue:22 pages:8888-8895 status: published

Polythiophenes with alcohol, tosylate, azide, ethynylene, carboxylic acid, and amine end groups were prepared by a combination of functionalized nickel initiators and postpolymerization reactions. The azide and ethynylene polymers were subsequently used in a click reaction to produce a conjugated block copolymer. Finally, a conjugated triblock-copolymer was synthesized by means of a chain growth polymerization initiated by a binuclear nickel initiator. ispartof: Macromolecules vol:44 issue:15 pages:6017-6025 status: published