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Figure 1 . T g reductions in PS films on glycerol look more

Nanorheology of Ultrathin Polymer Films by Liquid Dewetting Gregory B. McKenna, Texas Tech University, DMR 0804438.

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Figure 1 . T g reductions in PS films on glycerol look more

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  1. Nanorheology of Ultrathin Polymer Films by Liquid DewettingGregory B. McKenna, Texas Tech University, DMR 0804438 New results from the PI’s laboratories have provided new insights into the behavior of ulrathin polymer films. First, new experiments in liquid dewetting of polystyrene show that the Tg reduction in films floating on liquid glycerol behave much like polymer films supported on rigid substrates. The comparison is shown in Figure 1 where we see that, in fact, the films floating on glycerol tend to show weaker glass transition reductions than do other films. These results show that surface constraint is not the cause of differences in Tg reductions, but that, as yet unelucidated, interfacial interactions are involved. The second novel result is the ‘record’ Tg reduction observed in nanobubble inflation measurements of polycarbonate films, which have air interfaces, of upwards of 120 oC when thickness decreases to 3 nm, as shown in Figure 2. Interfacial effects are the subject of ongoing investigations. Figure 1. Tg reductions in PS films on glycerol look more like supported films than freely standing films. (Response is even weaker than upper bound of supported films). Figure 2. Tg reduction comparisons for polycarbonate (PC), Polystyrene (PS) and poly(vinyl acetate) (PVAc) thin films.

  2. Nanorheology of Ultrathin Polymer Films by Liquid DewettingGregory B. McKenna, Texas Tech University, DMR 0804438 Figure 1. 2012 SIGT participants in Chemical Engineering at Texas Tech University. Graduate Student Mentors also shown. Outreach activities this past year focused on the Science-It’s a Girl Thing (SIGT) program at TTU. The program aspects in the Chemical Engineering Department are coordinated by Prof. S.L. Simon and the PI (McKenna) had one female graduate student funded by the present project participate in the SIGT program. Figure below shows the young girls who participated as well as the graduate student mentors on one day of the class. Three of the graduate students work with PI McKenna, one of them supported by the present project. The SIGT is aimed at girls from 5th -11th grades and is a residence camp at TTU with the goals to 1)Provide girls with strong role models, 2) Spark interest in science, 3) Dispel myths/misconceptions about science

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