Light scattering study of rigid, rodlike organometallic block copolymer micelles in dilute solution

The block copolymer poly(ferrocenyldimethylsilane-b-dimethylsiloxane) (PFS40-b-PDMS480, where the subscripts refer to the mean degree of polymerization) self-assembles in n-decane at 25 degrees C to form long rodlike micelles (Raez et al. J. Am. Chem. Soc. 2002, 124, 10381). Here, we describe a combination of static (SLS) and dynamic (DLS) light scattering measurements on solutions of the micelles in n-decane. By SLS, we find that the micelles are thin, rigid, rodlike structures with a mean length of similar to 960 nm in the limit of zero concentration and a length that increases with concentration. Through a combination of SLS and DLS measurements, we find that that the cross-sectional hydrodynamic diameter of the micelle is 18 nm. These self-assembled structures also appear to have a narrow distribution of lengths (with M-w/M-n approximate to 1.1). These structures are much smaller than those observed on transmission electron microscopy (TEM) grids obtained from solutions of these self-assembled structures.