Directed high- block copolymer self-assembly by laser writing on silicon substrate

Polymer self-assembly commonly suffers from retarded equilibrium structure formation caused by the large diffusion barrier of long-chain molecules. In particular, the defect annihilation kinetics of high-chi block copolymers (BCPs) are generally sluggish because of a slow inter-block chain diffusion process from strong inter-block segregation. Therefore, long-range order of high-chi BCPs still hard to be obtained by conventional approaches. Here, we introduce near-infrared laser photothermal treatment to effectively promote high-chi BCP self-assembly and demonstrating highly aligned nanoscale patterned structures on silicon substrates. Adequate molecular weight selection of high-chi PS-b-P2VP system enables one-time laser hot-zone annealing, resulting in highly ordered nanodomains along laser writing direction. Facile sub-sequential metal ion loading to P2VP cylinders enables the formation of highly aligned metal nanowires. Moreover, a commonly used silicon substrate without a photoabsorbing layer is employed as a photo-thermal substrate, demonstrating that the laser writing process is compatible with conventional semiconductor processes.