Synthesis and Characterisation of Polar PPV Derivatives through the Sulfinyl Precursor Route

Abstract

In Chapter 1 a general introduction on conjugated polymers and more specifically on poly- (para-phenylene vinylene) or PPV and its derivatives is presented. Different synthetic routes, all with their main properties and advantages, are described. Possible applications for these materials, such as light emitting diodes, photovoltaic cells and (bio)sensors are mentioned as well. The need for functional conjugated polymers is also expressed in the aim of the thesis. Chapter 2 deals with the synthesis and characterisation of some functional sulfinyl precursor polymers. The four different functional groups are a triethylene glycol derived chain, an alcohol function, an ester and a sulfonate salt. The functional groups are placed on the sulfinyl tail, which means that they will not be present in the conjugated analogues of the precursors. For the synthesis of the monomers some adaptations had to be made to the standard procedure for monomer synthesis because these normal conditions gave only very low yields of the desired thioethers. Diluting ten times versus the standard conditions gave the thioether in a high yield with no occurrence of the unwanted Wessling polymerisation. The polymerisation reactions of the different monomers were performed according to a standard procedure to afford the precursor polymer in high yield. This was true for the oligoethylene oxide monomer. The alcohol monomer gave an insoluble polymer due to strong hydrogen bonding. For the ester monomer, no polymerisation occurred but an E1cb elimination mechanism was found to explain this lack of polymerisation. Also the compatibility of the ester function with a sulfinyl group was demonstrated. Unlike the problems with solubility, the elimination behaviour of all precursor polymers was studied using different in situ techniques that are in good accordance with another. The experiments prove the possibility of synthesis of the functional PPV derivatives if some precautions are taken into account. The knowledge obtained from Chapter 2 will be of major use for the synthesis of the monomers and polymers described in Chapter 3. ...