Tin oxide nanostructure fabrication via sequential infiltration synthesis in block copolymer thin films

Tin oxide (SnO₂) nanostructures are attractive for sensing, catalysis, and optoelectronic applications. Here we investigate the fabrication of SnO_x nanostructures through sequential infiltration synthesis (SIS) in block copolymer (BCP) film templates. While the growth of metal and metal oxides within polymers and BCP films via SIS has been demonstrated until now using small precursors such as trimethyl aluminum and diethyl zinc, we hypothesize that SIS can be performed using larger precursors and demonstrate SnO_x SIS with tetrakis(dimethylamino)tin (TDMASn) and hydrogen peroxide. Tuning the SIS reaction and BCP chemistry resulted in highly ordered, polystyrene-block-poly(2-vinyl pyridine) (P2VP)-templated porous SnO_x - AlO_x and SnO_x nanostructures. Detailed investigation using in-situ microbalance, high resolution electron microscopy, elemental analysis and infra-red spectroscopy shows that SnO_x can directly grow within P2VP homopolymer and BCP films. Simultaneously with the growth, SnO_x SIS process also contributes to the polymer etch. Performing SnO_x SIS with pretreatment of a single AlO_x SIS cycle increases the SnO_x growth and protects the BCP template from etching. This is the first report of SnO_x SIS opening a pathway for additional tetrakis-based organometallic precursors to be utilized in growth processes within polymers.