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- Englisch (3) (entfernen)
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- Steel in concrete (2)
- Cathodic Protection (1)
- Cathodic protection (1)
- Chloride Migration (1)
- Electrochemical impedance spectroscopy (1)
- LIBS (1)
- Mass spectrometry (1)
- Mild steel (1)
- Pitting corrosion (1)
- Polymers (1)
The development of a facile covalent strategy for the fabrication of organic conducting polymers (OCPs)/carbon nanotubes (CNTs) based molecular hybrid materials remains a challenge and is expected to address the detrimental intrinsic bundling issue of CNTs. In view of the pristine CNTs' ability to undergo Diels–Alder reactions with dienes, we report the synthesis of a novel poly(3-hexylthiophene) (P3HT) based organic conducting polymer (OCP) with terminal cyclopentadienyl (Cp) groups. The synthetic strategy employed is based on a combination of in situ end group functionalization via Grignard metathesis (GRIM) polymerization and a subsequent end group switching via reaction with nickelocene. Characterization data from Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDITOF MS) fully support the successful synthesis of monofunctional Cp-capped P3HT, which was found to be highly reactive toward dienophile end-capped polystyrene (PS). The Cp-capped P3HT was subsequently ligated to the surface of pristine single walled CNTs (SWCNTs). The resulting P3HT/SWCNTs molecular hybrid material was characterized using thermogravimetric analysis (TGA), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), and high resolution transmission electron microscopy (HRTEM). The data from TGA, EA, and XPS were used to quantitatively deduce the grafting density. P3HT/SWCNTs prepared with Cp capped P3HT was found to contain 2 times more P3HT than the reference sample, featuring a grafting density of 0.0510 chains·nm–2 and a periodicity of 1 P3HT chain per 748 carbon atoms of the SWCNTs. HRTEM revealed individual SWCNTs wrapped with P3HT whereas in the reference sample P3HT was adsorbed on the bundles of the SWCNTs. The results presented here provide a new avenue for designing novel materials based on CNTs and OCPs.
At the Institute for Building Materials Research (ibac) in Aachen and the Federal Institute for Materials Research and Testing (BAM) in Berlin a joint research project is currently running with the aim to develop a numerical model which describes cathodic protection (CP) of reinforced concrete. Special project focus is the CP of the rear reinforcement layer. The resulting model shall include the impact of chemical alterations at the steel surface and within the adjacent concrete on the polarisation behaviour of reinforcement, which are induced by long-term application of CP. The investigations presented in this paper aim to clarify open aspects on the migration of chloride ions due to small electric fields as applied in CP of steel in reinforced concrete structures. A comparatively new method, laser induced breakdown spectroscopy (LIBS), was applied in order to determine chloride concentration profiles on laboratory specimens as one of several model parameters for a mathematical description of CP of the rear reinforcement of reinforced concrete structures. The paper concerns migration tests using non-saturated specimens under laboratory conditions at constant voltage and the application of the experimental parameters on FEM-calculations. The presented results suggest the conclusion that even comparably small electric fields, as applied in CP of steel in concrete, may lead to significant and sustainable reduction in chloride concentration at the surface of the reinforcement.