Figure 5.

¹H NMR spectra recorded for a PDMAC₅₀₀ (red spectrum) and a PMPC₁₃₉ (blue spectrum) homopolymers in the absence of salt, as well as a PMPC₁₃₉–PDMAC₅₀₀₀ diblock copolymer prepared at 20% w/w in D₂O in the presence of 2.0 M ammonium sulfate, see the lowest black spectrum. As the 20% w/w PMPC₁₃₉–PDMAC₅₀₀₀ dispersion is diluted with further D₂O, both the background salt concentration and the copolymer concentration are systematically reduced (see four other black spectra). Just a two-fold dilution of the turbid dispersion is sufficient to cause molecular dissolution of the particles as the PDMAC block becomes solvated in 1.0 M ammonium sulfate. A further two-fold dilution of this transparent solution with D₂O results in PMPC₁₃₉–PDMAC₅₀₀₀ chains dissolved in 0.5 M ammonium sulfate, for which the PDMAC signals are now indistinguishable from those of PDMAC₅₀₀ homopolymer in water (compare the uppermost black spectrum with the red spectrum).