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Creators/Authors contains: "Stefan, Mihaela C."

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  1. ; ; ; (, ACS Applied Polymer Materials)
    Kirk S. Schanze, editor-in-chief (Ed.)
    Nanoindentation is an optimal technique for the measurement of thin film mechanical properties. Polymers present a unique problem in that their response to loading is time-dependent. Due to this, many of the most common nanoindentation methods are not suitable for probing polymer nanoscale properties. Despite this issue being well-known for decades, poly(3-hexylthiophene) has been exclusively analyzed by time-independent mechanical properties testing methods. Herein, we present a nanoindentation technique that analyzes the materials’ time-dependent response under both constant rate loading and step loading. By determining viscoelastic functions, we are able to extract the Young’s relaxation modulus of poly(3- hexylthiophene). The average Young’s modulus acquired from viscoelastic nanoindentation is determined to be 260 ± 27 MPa. These results are in excellent agreement with specialized mechanical tests for thin 
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  2. ; ; ; ; ; ; ; ; ; (, The Journal of Physical Chemistry C)
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