Laser ablation of block copolymers with hydrogen-bonded azobenzene derivatives

Supramolecular assemblies （PS-b-P4VP （AzoR）） are fabricated by hydrogen-bonding azobenzene derivatives （AzoR） to poly（4-vinyl pyridine） blocks of polystyrene-block-poly（4-vinyl pyridine） （PS-b-P4VP）. PS-b-P4VP（AzoR） forms phase separated nanostructures with a period of-75-105 nm. A second length scale structure with a period of 2μm is fabricated on phase separated PS-b-P4VP（AzoR） by laser interference abla- tion. Both the concentration and the substituent of AzoR in PS-b-P4VP（AzoR） affect the laser ablation process. The laser ablation threshold of PS-b-P4VP（AzoR） decreases as the concentration of AzoR increases. In PS-b-P4VP（AzoR） with different substituents （R = CN, H, and CH3）, ablation thresholds follow the trend： PS-b-P4VP（AzoCN）〈 PS-b- P4VP（AzoCH3）〈PS-b-P4VP（AzoH）. This result indicates that the electron donor group （CH3） and the electron acceptor group （CN） can lower the ablation threshold of PS-b-P4VP（AzoR）.