Patchy worm-like micelles: solution structure studied by small-angle neutron scattering

TL;DR

This study uses small-angle neutron scattering with contrast variation to confirm the patchy corona structure of worm-like micelles formed by triblock terpolymers in solution, clarifying their in-situ organization.

Contribution

It introduces a contrast variation method in SANS to distinguish patchy from Janus-type micelle structures in solution.

Findings

Confirmed patchy corona structure in solution

Validated the use of contrast variation in SANS for structural discrimination

Provided in-situ evidence supporting the patchy model

Abstract

Triblock terpolymers exhibit a rich self-organization behavior including the formation of fascinating cylindrical core-shell structures with a phase separated corona. After crystallization-induced self-assembly of polystryrene-(block)-polyethylene-(block)-poly(methyl methacrylate) triblock terpolymers (abbreviated as SEMs = Styrene-Ethylene-Methacrylates) from solution, worm-like core-shell micelles with a patchy corona of polystryrene and poly(methyl methacrylate) were observed by transmission electron microscopy. However, the solution structure is still a matter of debate. Here, we present a method to distinguish in-situ between a Janus-type (two faced) and a patchy (multiple compartments) configuration of the corona. To discriminate between both models the scattering intensity must be determined mainly by one corona compartment. Contrast variation in small-angle neutron scattering enables us to focus on one compartment of the SEMs. The results validate the existence of the patchy structure also in solution.