We developed a strategy to make model hyperbranched structure with uniform subchains and controlled locations of cleavable linkages. First, a novel seesawtype tetrafunctional initiator with one alkyne, one disulfide linkage, and two bromine groups (≡−S−S−(Br) 2 ) was prepared. Using such an initiator, an AB 2 -type macromonomer (azide∼∼alkyne∼∼azide) with one disulfide linkage at its center was prepared via successive atom transfer radical polymerization (ATRP) and azidation substitution reaction, where ∼∼ represents polystyrene chains. Further interchain "clicking" coupling between the azide and alkyne groups on the macromonomers led to model hyperbranched polystyrenes with uniform subchains and controllablly located cleavable disulfide linkages. The 1 H nuclear magnetic resonance spectra, Fourier transform infrared spectroscopy, and size exclusion chromatography with a multiangle laser light scattering detector confirmed the designed degradable hyperbranched structure. Armed with this novel sample, we studied its dithiothreitol (DTT)-induced degradation in various organic solvents by a combination of static and dynamic LLS. We found that the cleavage of disulfide bonds contains a fast and a slow process. The fast one reflects the degradation of disulfide bonds on the chain periphery; while the slow one involves those inside. Both the fast and slow degradation reaction rate constants (K fast and K slow ) are a linear function of the initial DTT concentration ([DTT] 0 ), but the relative contribution of the two processes is mainly governed by the hyperbranched chain structure, nearly independent of [DTT] 0 .

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Amphiphilic 8-shaped cyclic-(polystyrene-b-poly(acrylic acid))2 with two rings and its linear precursor, i.e., 8-shaped cyclic- and linear-(PS–PAA)2, were successfully prepared by a combination of atom transfer radical polymerization (ATRP) and “click” chemistry. Using various methods, we characterized those intermediates and resultant copolymers and studied their association properties in solutions. As expected, the average aggregation number (⟨N agg⟩) increases with the molar fraction of styrene for a given overall degree of polymerization. Our results reveal that the cyclization leads to a smaller ⟨N agg⟩ but slightly larger and looser aggregates, presumably due to the topological constraint of the two rings (8-shaped). Using these amphiphilic chains as emulsifying agents, we found that 8-shaped cyclic-(PS–PAA)2 chains are less effective in stabilizing latex particles in emulsion polymerization because each cyclic chain occupies a smaller interfacial surface area than its linear counterpart. Further, using pyrene as a model hydrophobic molecule, we investigated their solubilization powers. Our results reveal that 8-shaped cyclic- and linear-(PS–PAA)2 chains have a similar ability in loading hydrophobic pyrene molecules, different from our original expectation, presumably because the hydrophobic PS block is too short and the hydrophilic PAA rings are too small. The current study provides a better understanding of the complicated topological constraint on the solution properties of 8-shaped cyclic amphiphilic copolymers.