Erratum: Graphitic nanofillers in PMMA nanocomposites-an investigation of particle size and dispersion and their influence on nanocomposite properties

Abstract

Published in J. Polym. Sci. Part B; Polym. Phys. 45, 2097–2112 (2007) Upon a recent review of the findings in this article, the authors have determined that the temperature-dependent profiles for the storage modulus (E') and tan δ of the pure poly(methyl methacrylate) (PMMA) sample (referred to as “0%particle/PMMA” where “particle” refers to ARG (as-received graphite), EG (expanded graphite), or GNP (graphite nanoplatelets)) were erroneously plotted. The E' and tan δ data for neat PMMA in the original Figure 6 and Figure 7, respectively, were from an incorrect and inadvertently shifted dataset (resulting from a copying error of data between spreadsheets). The correct profiles are plotted in Figure 1 below. Since the focus of the original article was on the influence of particle size and dispersion of different graphitic particles on the properties of polymer nanocomposites, with an emphasis on detailed microscopy and image analysis, these corrections do not alter the major points and conclusions of the original manuscript. Correct storage modulus (top panel) and tan delta (bottom panel) profiles for the control PMMA sample. The plotted data are representative profiles from multiple replicates of shear mix-processed PMMA samples without nanofiller. For comparison, the previously reported profiles (incorrect) for neat PMMA and the originally reported profiles for the 1% ARG/PMMA nanocomposite sample (taken from Figures 6 and 7 from the original manuscript) are also included. In the published Table 5, the storage moduli of the polymer nanocomposites were compared to the modulus of neat PMMA, stated to be 2.1 GPa at 25 °C (Table 5 footnote). The correct comparison value is now 2.2 GPa. This small correction does not significantly affect the relationship to the reported E' values for the composites (values ranging from 2.9–4.9 GPa). From the corrected tan δ profile for PMMA shown in Figure 1 below, the baseline glass transition temperature (Tg) for PMMA is now 97 °C (i.e., the 0% filler data point in the published Figure 11 is now 97 °C), 2 °C above the 95 °C data point shown in the published article. Thus, the reported largest increase in Tg of 43 °C (right column of page 2104 of the original manuscript) for the 1% ARG/PMMA nanocomposite is now 41 °C. This minor correction does not change the original conclusion that the polymer nanocomposites have significantly higher Tgs than neat PMMA at low loadings of nanofiller. That the processed pure PMMA in this study consistently exhibited an average Tg of 97 °C is likely due to the harsh shear mixing conditions used in sample preparation. The Tg of the as-received PMMA is reported by the supplier (Polysciences, Inc.) to be 105 °C, which was also obtained in processed control samples for other works (J. Polym. Sci. B: Polym. Phys. 2005, 43, 2269–2279 and Nat. Nanotechnol. 2008, 3, 327–331). Finally, the polydispersity (PDI) of the PMMA reported in the original article should be 2.7, as nominally listed by the supplier for lot number 504681. The originally reported PDI value of 2.1 was a typo. We apologize to the readers of J. Polym. Sci. Part B; Polym. Phys. for any inconvenience the aforementioned errors may have caused.