Beyond the Conventional Paradigm of Radial (Normal) Stretching of Tethered Chains. Do Theories of Micellization in Solutions of Block Copolymers Need to Be Revised?

We have studied conformations of a single tethered chain, chains in a planar brush, and corona-forming blocks in diblock copolymer micelles using dissipative particle dynamics. Interactions of all components of the systems were considered explicitly. In addition to the conventionally studied normal elongation of the chains in the brush and micellar corona, we detect regimes of partial or full adsorption of the tethered chains. They are realized for compatible with the substrate (interface) chains (blocks) and solvophobic surfaces (strongly selective solvent for the copolymer). The physical reason for the adsorption is shielding of unfavorable solvent-substrate (or micellar core-solvent) contacts by polymers. In the case of block copolymer micelles, adsorption-desorption of the corona-forming blocks can induce morphology transformation which cannot be predicted/described by traditional theories.

Automated summary

We used dissipative particle dynamics to study the conformations of a single tethered chain, chains in a planar brush, and corona-forming blocks in diblock copolymer micelles. The interactions between all components of the systems were explicitly considered. In addition to the normal elongation observed in the brush and micellar corona, we found regimes of partial or full adsorption of the tethered chains. These adsorption regions occur when the chains (blocks) are compatible with the substrate (interface) or solvophobic surfaces that strongly select the copolymer solvent. The adsorption is attributed to the shielding effect of polymers on solvent-substrate (or micellar core-solvent) contacts. In the case of block copolymer micelles, the adsorption-desorption of the corona-forming blocks can induce morphology transformations that cannot be predicted or described by traditional theories.