Nanomechanical properties of poly(para-phenylene vinylene) determined using quasi-static and dynamic nanoindentation

Mechanical properties of poly(p-phenylene vinylene) (PPV) were determined by quasi-static and dynamic nanoindentation. PPV films were prepared by thermolytic conversion of poly[p-phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures. The mechanical properties of the films showed a dependence on the extent of conversion and chemical composition of the films. The storage modulus, Er′, and plasticity decreased with an increase in conversion, whereas the loss modulus, Er″, showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower Er″ than Er′, consistent with the glassy nature of the polymers at room temperature. The fully-converted PPV polymer was found to have room-temperature storage and loss moduli of 4.4 and 0.2 GPa, respectively. A comparison of the contact mechanical properties of the isotropic PPV films synthesized in this work with previously reported values for stretch-oriented anisotropic films determined by conventional tensile testing methods is also discussed.