Date/Time: 04-24-2019 - Wednesday - 05:00 PM - 07:00 PM
Luke Galuska1 Kevin Ramos1 Song Zhang1 Xiaodan Gu1

1, The University of Southern Mississippi, Hattiesburg, Mississippi, United States

Conjugated polymers are showing ever increasing promise for both current and novel electronic applications. Much of the research for these materials has focused on optimizing electrical properties (such as OPV efficiency or electron mobility) at the detriment of understanding the mechanical properties which are necessary for device commercialization. One reason for this is that the active polymer layer is on the order of 100nm thick (or less) making direct mechanical characterization all but impossible. Our group has utilized the pseudo freestanding tensile test (film on water) to overcome this challenge enabling the calculation of parameters such as Young’s modulus and crack-onset-strain with minimal difficulty. This method has shown consistently lower modulus values than that obtained from buckling metrology. This may be due to a plasticization effect of the water, but the interaction of water with the thin film has not been sufficiently accounted for. Therefore, I will discuss a true free standing tensile test that provides direct mechanical characterization of conjugated polymeric thin films in air. This novel characterization technique was demonstrated on three polymer systems: polystyrene, poly(3-hexylthiophene-2,5-diyl), and polyfluorene at multiple film thicknesses to provide quantitative evidence of any measurable effect water induces in the pseudo freestanding tensile test. The film and bulk glass transition temperatures were measured via AC-chip calorimetry and DMA respectively. This enabled us to ascertain the effectiveness of this methodology across a broad range of dynamic systems. Furthermore, the free standing tensile test enabled in-situ characterization with darkfield microscopy under tensile strain thus providing further understanding in thin film deformation mechanics.

Meeting Program

Symposium Sessions

5:00 PM–7:00 PM Apr 24, 2019 (US - Arizona)

PCC North, 300 Level, Exhibit Hall C-E