Mechanism of liquid-phase metal infiltration into pyridine-containing polymeric thin films

Highly Ordered Porous Inorganic Structures via Block Copolymer Lithography: An Application of the Versatile and Selective Infiltration of the “Inverse” P2VP-b-PS System

“…It is evident that the metals were selectively infiltrated into the P2VP domain of the film maintaining the BCP self-assembled pattern and avoiding the step of ethanol activation, required for other polymers. Although the number of defects on the metal oxide pattern is slightly higher than that on the BCP pattern, it is possible to observe that the oxide pattern reproduces well the BCP template, which is confirmed by similar values of pore diameter 56 However, the rate of diffusion into the pyridine group will also depend on the type of ion. 32 Therefore, it is likely that chromium, iron, and gallium ions exhibited a higher interaction with the P2VP layer compared to nickel ions, leading to a more ordered pattern.…”

“…To study the capacity and the versatility of P2VP in creating ordered domains, selective metal infiltration via spin coating of the precursor solutions onto the highly ordered BCP thin films was studied followed by the conversion of the metal ions to their metal oxides by UVO treatment. Four different metal ions (chromium (Cr 3+ ), nickel (Ni 2+ ), iron (Fe 3+ ), and gallium (Ga 3+ )) were selected to be infiltrated into the ordered BCP thin films based on previous reports. ,,, In metal infiltration studies, an ethanol swelling treatment is commonly applied to increase interaction between the metal and the desired block by creating a porous structure. ,, However, for the BCP analyzed in this research (P2VP-majority), it was not possible to apply this procedure. The EtOH swelling led to the film destruction and the loss of pattern, possibly due to ethanol’s selectivity toward the P2VP block, thus resulting in a complete collapse of the matrix (SI Figure S2).…”

“…The metal ions can interact with the P2VP block by coordination and π–π* interactions as underlined by previous studies. Moreover, the presence of oxyanions may possibly have resulted in better infiltration . However, the rate of diffusion into the pyridine group will also depend on the type of ion .…”

“…Four different metal ions (chromium (Cr 3+ ), nickel (Ni 2+ ), iron (Fe 3+ ), and gallium (Ga 3+ )) were selected to be infiltrated into the ordered BCP thin films based on previous reports. 35,47,55,56 In metal infiltration studies, an ethanol swelling treatment is commonly applied to increase interaction between the metal and the desired block by creating a porous structure. 37,57,58 However, for the BCP analyzed in this research (P2VP-majority), it was not possible to apply this procedure.…”

Liquid Phase Infiltration of Block Copolymers

“…In the literature, many different terminologies have been used to describe this process, such as LPI [ 16 , 17 ], ion adsorption [ 18 ], aqueous metal reduction [ 19 ], metal ion loading [ 15 ], metal inclusion [ 20 ] and metal incorporation [ 21 ]. Although each one might indicate a different interaction mechanism between the metal precursor and the polymeric template (complexation or electrostatic) or different process conditions (neutral or acidic), they all can be referred to as a liquid phase route to selectively localise metal salt precursors into one of the BCP nanodomains.…”