Crystallinity-driven morphological ripening processes for poly(ethylene oxide)-block-polycaprolactone micelles in water

Transcription

1 Supporting Information: Crystallinity-driven morphological ripening processes for poly(ethylene oxide)-block-polycaprolactone micelles in water Georgios Rizis, Theo G. M. van de Ven*, Adi Eisenberg* Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec, Canada, H3A 2K6 and Centre for Self-Assembled Chemical Structures (CSACS). *Corresponding authors. ; 1

2 Figure SI-1. Monomodal size distributions observed by DLS characterization immediately following micellization. The solvent composition is 17% (v/v) aqueous dioxane. 2

3 Figure SI-2. Representative DLS data for fresh micellar preparations of PEO 45 -b-pcl 26. Sample history (top to bottom): structures obtained right after micellization (solvent is 17% (v/v) aqueous dioxane); dialyzed micellar preparations (containing large aggregates/rods); dialyzed samples following filtration (0.45 μm cutoff). For this particular sample, note that the removal of large aggregates was incomplete, leading to a bimodal size distribution. 3

4 Figure SI-3. Representative TEM images showing the co-existence of spheres and rods in samples of PEO 45 -b-pcl 18 (top) and PEO 45 -b-pcl 24 (bottom). The scale bars are 200 nm. 4

5 a c b Figure SI-4. Thermally-induced rod-to-sphere transitions. The size distributions obtained by DLS shift from large structures in extensively-aged samples, to small micelles after heating to 65 o C (for 20 minutes) in samples of a) PEO 45 -b-pcl 18 and b) PEO 45 -b-pcl 24, respectively. Representative TEM images are shown in c) for PEO 45 -b-pcl 24 before (top) and after (bottom) the melting process. The scale bars are 1 μm (top) and 200 nm (bottom). 5

6 a c b Figure SI-5. Morphological transformation profile of PEO 45 -b-pcl 26 micelles assessed by light scattering measurements at three different angles. Scattering intensity measurements are represented in plots of a) the normalized intensity (I t /I o ) as a function of time measured simultaneously at 3 angles (listed next to each curve), and b) the intensity ratio between measurements performed at scattering angles of 45 o and 135 o, for which the scattering volumes (proportional to sin(θ)) are the same. DLS data are shown in c) for the 5-hour time points in graphs a) and b). Note the increased relative scattering by the large aggregates at smaller angles. 6

7 Figure SI-6. Typical DLS size distributions obtained as a function of time for samples of PEO 45 - b-pcl 18 (left) and PEO 45 -b-pcl 24 (right). 7

8 a b Figure SI-7. Morphological transformation profile of PEO 45 -b-pcl 10 micelles. a) Size distributions of samples immediately after self-assembly (Start) and after 5 hours; changes were associated with a 10-fold increase in scattering intensity (data not shown). b) Representative TEM images of rod micelles in PEO 45 -b-pcl 10 samples. The dark accumulations are most likely drying artifacts associated with the use of phosphotungstic acid as a negative stain. The scale bars are 500 nm. 8

9 a d b c Figure SI-8. Size distributions micelles at various concentrations in water obtained. Samples of PEO 45 -b-pcl 26 were analyzed by DLS a) immediately following preparation; b) after 3 hours; and c) after 2 days. Note the similarity between data obtained from samples of varying concentrations. The first detectable sample transformation (shown in b) occurs at the same time for all concentrations. d) Typical TEM images obtained in dilute samples of PEO 45 -b-pcl 18 (top, aged 10 days) and PEO 45 -b-pcl 26 (bottom, aged 1 day); the concentration differs by a dilution factor of 4 with respect to the samples discussed in the main text. The scale bars are 2 μm (top) and 500 nm (bottom). 9

10 Figure SI-9. Estimate of the critical micelle concentration of PEO 45 -b-pcl 26 in water. The graph shows the light scattering intensity (solvent-subtracted) as a function of concentration for freshly-prepared micellar samples; results obtained by diluting pre-formed micelles are similar (shown in overlay). The discontinuity observed just above 10-4 g/l denotes the CMC, as indicated by the arrow). 10