Tuning of the Exchange Dynamics of Unimers between Block Copolymer Micelles with Temperature, Cosolvents, and Cosurfactants

Abstract

The dynamics of unimer exchange between aqueous micelles, formed by two amphiphilic block copolymers, i.e., poly(styrene-b-sodium methacrylate) and poly(tert-butylstyrene-b-sodium methacrylate), has been investigated by steady-state fluorescence spectroscopy. The kinetics are so slow at room temperature that no exchange could be detected over several hours, while at 60 °C the exchange rate constants could be estimated. These results corroborate our previous findings that the rate is slowed down by increasing the hydrophobicity of the core. In addition to the temperature, the exchange can also be tuned by the addition of either a cosolvent or a cosurfactant. The efficiency of these additives to speed up the exchange process is related to their water solubility and their compatibility with the hydrophobic core of the micelles. The most pronounced effect on the exchange process is observed when the water solubility is low and the mixing of the additive with the hydrophobic core is favorable.

Hydrolysable core-crosslinked thermosensitive polymeric micelles: Synthesis, characterisation and in vivo studies

“…4). It is known at low concentrations of SDS that the exchange rate between unimers and micelles is accelerated while at higher concentrations, the present SDS micelles solubilise the amphiphilic block copolymers resulting in destabilisation of the PM [56]. In contrast, upon addition of SDS to CCL micelles the particles did not fell apart, but an increase in size from 69 to 132 nm was observed (Fig.…”

Block‐Selective Solvent Influence on Morphology of the Micelles Self‐Assembled by PS38‐b‐P(AA190‐co‐MA20)

“…[29][30][31] In this case, the T g of core-forming chains of PS 38 is about 65 8C, [32,33] which is much higher than the room temperature. Thus, so-called ''frozen micelles'' are formed when excess amount of the binary solvent mixture of water and acetone in added into the amphiphilic block copolymer solution in DMF.…”

Triblock copolymers of styrene and sodium methacrylate as smart materials: synthesis and rheological characterization

“…Observations indicate that these block copolymers often behave as kinetically "frozen" micelles [28,29]. In literature it is described that amphiphilic block copolymers display very low diffusion coefficients.…”