The polycationic polyelectrolyte poly(methacryloylethyltrimethylammonium methyl sulfate) (PMETMMS) of high molecular weight (ca. 26 × 10 6 g mol -1 ) in dilute solutions with acetone−water mixtures displays a coil−globule transition above a certain threshold of acetone. SANS observations of this system indicate that the collapsed state of this molecule consists of a sequence of dense spheres with smooth surfaces connected by regions of loose polymer. The radius of the spheres, 28 nm, is smaller than either the hydrodynamic radius ( R H = 39 nm) or the radius of gyration ( R G = 42 nm). The number of such collapsed regions is small (3−4), the volume fraction of polymer inside them being about 8%.
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Aseyev et al. (2001) studied this question.