Small-angle X-ray scattering

Polymer chemistry

Phase transition

Nucleation

Optics

Oligomer

Physical chemistry

Engineering

Lyotropic

Liquid crystalline

Chemical engineering

Thermodynamics

Phase (matter)

Organic chemistry

Crystallography

Chemical physics

Micelle

Aqueous solution

Chemistry

Scattering

Materials science

Physics

ACS Central Science

Small-angle X-ray scattering analyses reveal that the hydrated diblock oligomer n-C16H23(OCH2CH2)20-OH (C16E20 or Brij 58) forms lyotropic liquid crystals (LLCs) exhibiting face-centered cubic (FCC), body-centered cubic (BCC), Frank-Kasper (FK) A15, and cylindrical (HI) morphologies over the concentration range 30-65 wt % amphiphile. Heating LLCs comprising 54-59 wt % C16E20 drives the temperature-dependent phase transition sequence: A15 → BCC → HI. However, rapidly quenching the resulting HI phase from 70 to 25 °C initially forms a BCC phase that isothermally transforms into a complex, tetragonal FK σ phase comprising 30 quasispherical micelles. The metastability of this micellar σ phase is shown to depend on the sample cooling rate, thermal quench depth, and isothermal annealing temperature. We rationalize the preference for the A15 structure at 25 °C in terms of minimizing unfavorable water/hydrophobic contacts, while maximizing local particle sphericity. The symmetry breaking transition kinetics in these ...

Path-Dependent Preparation of Complex Micelle Packings of a Hydrated Diblock Oligomer