A Light Scattering Study of the Association of Hydrophobically α- and α,ω-End-capped Poly(ethylene oxide) in Water

Tumor pH-responsive flower-like micelles of poly(l-lactic acid)-b-poly(ethylene glycol)-b-poly(l-histidine)

“…Similar results have been observed with BAB (hydrophobic B blocks and hydrophilic A block) type amphiphilic copolymers which form flower-like micelles and often lead to micellar bridging (resulting in micelle aggregation) depending on environmental conditions [34][35][36][37][38]. For example, the formation of three-dimensional networks by bridging between micelles has been induced by high polymer concentration, salts and pH [34][35][36][37][38]. It is expected that as the pH of solution decreases, the PLA-b-PEG-b-polyHis micelles swell (Fig.…”

Structure and Properties of Hydrophobically End-Capped Poly(ethylene Oxide) Solutions in the Presence of Monovalent and Divalent Cations

“…This result tends to emphasize the role of bridging on viscosity especially in the light of the theory of Semenov et al, which predicts a jump in viscosity due to micelles interpenetration (9). Bridges are also responsible for micelle aggregation between CAC and C * f , in which case a more progressive open association model is relevant (7). When micelles are close to each other (concentration near C * f ) they repel and organize either into a local cubic order, leading to a correlation peak in neutron scattering spectra, or into a long-range cubic order corresponding to up to 6 Bragg peaks in X-ray scattering spectra (4,10).…”

“…By comparing the concentration dependence of the scattered intensity of monofunctionalized samples and difunctionalized ones, we were able to demonstrate that micellization can be described through a model of "closed association" (7). Independent experimental studies have led another group to the same conclusions (22).…”

“…Static light scattering experiments have already been performed on these associative polymers in pure water (7). It is known that the variation in scattered intensity versus concentration reflects the increase in average molecular weight, M w , due to association and the terms of interaction between micelles (viriel coefficients A 2 , A 3 , etc.)…”

“…Such associations, limited by micelle size and repulsions between PEO in hydrophilic corona, follow a closed association model (7). At higher concentrations, near the overlap concentration, C * f , viscosity jumps abruptly with α,ω-HMPEO, while the increase in viscosity of α-HMPEO does not diverge much from that of unmodified PEO, even when C > C * f (8).…”