Star-Like Micelles with Star-Like Interactions: A quantitative Evaluation of Structure Factor and Phase Diagram

TL;DR

This study investigates the phase behavior and interactions of star-like micelles formed from PEP-PEO block copolymers, demonstrating how their structure and phase transitions can be controlled and predicted through experimental and theoretical analysis.

Contribution

It provides a quantitative evaluation of the structure factor and phase diagram of star-like micelles, linking experimental results with theoretical models for star polymers.

Findings

Structure factors match effective star polymer potentials

High accuracy in predicting liquid/solid phase transitions

Observation of bcc and fcc phases depending on functionality

Abstract

PEP-PEO block copolymer micelles offer the possibility to investigate phase behaviour and interactions of star polymers (ultra-soft colloids). A star-like architecture is achieved by an extremely asymmetric block ratio (1:20). Micellar functionality f can be smoothly varied by changing solvent composition (interfacial tension). Structure factors obtained by SANS can be quantitatively described in terms of an effective potential developed for star polymers. The experimental phase diagram reproduces to a high level of accuracy the predicted liquid/solid transition. Whereas for intermediate f a bcc phase is observed, for high f the formation of a fcc phase is preempted by glass formation.