Previously, UC Santa Barbara MRSEC researchers demonstrated that chain-end functionalization of immiscible polystyrene/polydimethylsiloxane (PS/PDMS) blends with oppositely paired acid and base groups forms ionic supramolecular block copolymers, where electrostatically stabilized microdomains prevent macroscopic phase separation.
In this work, we developed a facile strategy to dynamically tune ionic interactions through light irradiation, enabling morphological transitions within a single polymer blend by post-functionalizing PDMS with a photochromic end-group.
Photoisomerization increases the local positive charge, strengthening ionic bonds between dissimilar blocks while enhancing repulsion between adjacent groups. This electrostatic repulsion expands the interfacial area per polymer chain, driving a HEX-to-LAM a phase transition.
By leveraging controllable end-group photochemistry, this methodology can enable the construction of microstructured functional polymeric materials with a wide tunability window.
