Linear, Star, and Comb Oxidation-Responsive Polymers: Effect of Branching Degree and Topology on Aggregation and Responsiveness.
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-1for 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.
NorthWest Center for Advanced Drug Delivery (NoWCADD), Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, M13 9PT, UK.
Richard
R
d'Arcy
NorthWest Center for Advanced Drug Delivery (NoWCADD), Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, M13 9PT, UK.
Arianna
A
Gennari
NorthWest Center for Advanced Drug Delivery (NoWCADD), Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, M13 9PT, UK.
Roberto
R
Donno
NorthWest Center for Advanced Drug Delivery (NoWCADD), Division of Pharmacy and Optometry, School of Health Sciences, University of Manchester, Manchester, M13 9PT, UK.
Nicola
N
Tirelli
D007700:Kinetics; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry
D011108:Polymers; D013501:Surface-Active Agents
branching; drug delivery; micelles; polysulfides; star polymers