Thin film self-assembly of multi-arm star PS-P2VP block copolymers

The variable architectures and controllable composition of star block copolymers (s-BCP) provide exceptional opportunities to manipulate their self-assembly in both bulk and thin films. We synthesized multi-arm s-BCPs with a polystyrene (PS) core and poly (2-vinyl pyridine) (P2VP) shell. Affinity of the hydrophobic PS core to the air and the hydrophilic P2VP shell to the substrate intrinsically influence the s-BCPs chain orientation at polymer-air and polymer-substrate interfaces. The star core-shell architecture and different arm numbers further affect their thin film self-assembly. Increasing the arm number from 2, 3 to 4 make the lamellar orientation change from parallel to perpendicular to hybrid. The formation mechanism of these arm-number-dependent orientations is elucidated through surface morphology analysis using atomic force microscopy (AFM) and depth-resolved orientation profiling via grazing-incidence small-angle neutron scattering (GISANS).



This work was supported by the Air Force Office of Scientific Research under contract FA9550-25-1-0003 and Army Research Office under contract W911NF-24-2-0041.