Analysis of the 2 H NMR spectra enabled us to determine the fraction of C30d molecules located in different environments in our samples. An upper limit to the amount of bulk alkane, i.e. C30d molecules that did not enter the lipid membranes, can be estimated by a subtraction method . The spectrum of pure C30d in the melt is fitted, and then a fraction of the resulting Lorentzian line shape is subtracted from the C30d/DMPC spectrum until an intensity of nearly zero is reached in the center of the spectrum (Figure ). The difference between the original and the reduced spectrum then corresponds to an upper limit for the bulk alkane fraction, and is 10-15 %. We determined that this small amount of bulk C30d is not sufficient to account for the crystalline signal observed at e.g. 55 • C. This was done by comparing the 2 H signal intensities across different temperatures, as described in more detail in the SI (Figure ). From these calculations we obtain that, at 55 • C, more than nearly 70 % of the molecules that comprise the crystals must have been dispersed inside the DMPC membranes prior to crystallization. We conclude therefore that our samples contain not only two, but three different types of C30d molecules: Phase-separated bulk alkane, and chains incorporated in the membrane that can be divided into those that crystallize at similar temperatures to bulk C30d, and those that remain in a liquid state at temperatures much lower than the bulk crystallization temperature.