Haitang Wang and Shawn D. Wettig

Phys. Chem. Chem. Phys., 2011, 13, 637-642 (DOI: 10.1039/c0cp00146e). Amendment published 11th May 2011

Method

The method reported on p. 638 incorrectly identified a Philips CM 10 electron microscope as the instrument used to collect the images, and an incubation time of 15 s. The corrected procedure is presented here:

Transmission electron microscopy (TEM)

The morphology of the phy-3-m compounds was observed by TEM. A 20 µL aliquot of each sample was dropped on a 300 mesh carbon coated copper grid for 30 to 60 s. The excess sample was drained off with filter paper and the deposited particles were stained with 1% (w/v) phosphotungstic acid (pH adjusted to 7 with 0.1 M NaOH) for 20 s and blotted with filter paper. The dried sample was examined with a JEOL 2010F TEM at the Canadian Centre for Electron Microscopy at McMaster University (Ontario, Canada). Measurements of bilayer thickness were made using a basic graphic drawing program and calibrating the resolution bar on each image to a known number of pixel elements. Measurements were made on three separate images at a minimum of three independent sites on each image for both the phy-3-12 and 12-3-12 systems (n = 9, average standard deviation = 0.2 nm).

Results and discussion

The discussion on p. 640 regarding the TEM images has been revised as follows:

TEM images of the phy-3-12 and 12-3-12 support the conclusion that the phy-3-m compounds preferentially form a stacked bilayer-type of aggregate rather than spherical or the rod-like micelles typically observed in gemini surfactants having short spacer groups. As can be seen in Fig. 3, aggregates observed for the 12-3-12 surfactant (Fig. 3A) are smaller and less organized than those for the phy-3-12 (Fig. 3B). Analysis of the spacing between layers in Fig. 3B gives an average spacing of 4.6 (? 0.2; n = 9) nm, or approximately 2.3 nm as the thickness of a monolayer. This corresponds reasonably well with the calculated length of the phytanyl chain (2.174 nm or 21.74 Å from Table 2). The corresponding thickness of bilayer-like structure observed for the 12-3-12 aggregates (Fig. 3A) is approximately 3.2 (? 0.2; n = 10) nm, giving a monolayer thickness of 1.6 nm, again in good agreement with the calculated length of a dodecyl chain (1.667 nm or 16.67 Å from Table 2).

Fig. 3 on p. 641 contained incorrect, preliminary images. The correct figure is reproduced below.

Fig. 3 Electronic micrographs of (A) 12-3-12 and (B) phy-3-12, bar represents 50 nm. Concentrations of 12-3-12 and phy-3-12 were 4.9 and 0.35 mM, respectively.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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