Poly xanthate precursors

Abstract In situ spectroscopy is an important tool to characterize polymers synthesized via a precursor route. Highly conjugated polymers such as po y(p-phenylene vinylene) (PPV) and PPV derivatives are commonly prepared from a precursor polymer because the final polymers are very insoluble and intractable. Preparation in the precursor form enables the polymer materials to be cast as films. The PPV polymers are obtained from the precursor forms using a thermal elimination reaction. The exact conditions of the reaction are important as they influence the properties of the resultant polymer. The details of this thermal elimination reaction have been analyzed using thermal gravimetric analysis (TGA) coupled with infrared analysis of the evolved gas products. In situ infrared spectroscopy of the precursor films during thermal conversion to the polymers has provided further details about the elimination reaction. We have characterized PPV synthesized from a tetrahydrothiophenium monomer (sulfonium precursor route) and via the xanthate precursor route. PPV derivatives under study include poly(2,5-dimethoxy-p-phenylene vinylene) and poly(phenoxy phenylene vinylene). 

Figure 2. Synthesis of poly(p-phenylene vinylene)(PPV) via the xanthate precursor route...

The preparation of poly(2,5 dimethoxy phenylene vinylene)(DM-PPV) utilized the xanthate precursor route. Many similarities exist between the PPV xanthate thermal elimination and this PPV derivative. Previous studies had attempted to synthesis DM-PPV using the SPR method. The SPR resulted in gel formation during dialysis so that film casting was not possible. The XPR was successful in preparing precursor films that can be thermally converted to DM-PPV. The derivatives of PPV are useful to prepare a polymer with a shift in the absorbance and photoluminescence maximum. DM-PPV exhibits an 100 nm red shift as compared with PPV synthesized via the XPR. 

Figure 5. Three-dimensional temperature-infrared frequency-intensity plot of the reaction byproducts of the thermal elimination from xanthate poly(2,5-dimethoxy phenylene vinylene) precursor...

Padmanaban, G., K. Nagesh, and S. Ramakrishnan. 2003. Segmented poly(2-methoxy-5-(2-ethyl-hexyloxy)-l,4-phenylene vinylene) via xanthate and dithiocarbamate precursors A comparative study of thermal eliminations. / Polym Sci Part A Polym Chem 41 (24) 3929-3940. 

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