Linear, Star, and Comb Oxidation‐Responsive Polymers: Effect of Branching Degree and Topology on Aggregation and Responsiveness

• DOI: 10.1002/marc.201600481
• Publication Date: 2016-09-27T13:26:05Z
• Authors: Richard d'Arcy; Arianna Gennari; Roberto Donno; Nicola Tirelli
• Keywords: Kinetics; Surface-Active Agents; Polymers; 02 engineering and technology; 0210 nano-technology; Oxidation-Reduction

Families of amphiphilic oxidation‐responsive polymers (poly(ethylene glycol)‐polysulfides) with different architectures (linear, 4, 6, and 8‐armed stars and 10, 15, and 20‐armed combs) and compositions (variable ethylene sulfide/propylene sulfide ratio) are prepared. In water, all the polymers assemble in spherical micelles, with critical micellar concentrations <0.01 mg mL−1 for all the branched polymers. Triple‐detection gel permeation chromatography (GPC) and asymmetric field flow fractionation (AFFF) with dynamic and static light scattering detection, respectively, show an increasing compaction of the polymeric coil and a strong reduction of the aggregation number with increasing degree of branching. The key finding of this study is that the kinetics of the oxidative response sharply depend on the branching; in particular, it is highlighted that the degree of branching influences the lag time before a response can be observed rather than the speed of the response itself, a phenomenon that is attributed to a branching‐dependent solubility of the oxidant in the polysulfide matrix.image