Understanding Metal Oxides Growth Within Polymer Films

Neta Shomrata, Functional Nanostructures and Advanced Imaging Lab, The Wolfson Department of Chemical Engineering, Technion, Haifa, Israel
Tamar Segal-Peretz, Functional Nanostructures And Advanced Imaging Lab, The Wolfson Department Of Chemical Engineering, Technion, Haifa, Israel

Sequential Infiltration Synthesis (SIS) is a novel approach based on atomic layer deposition (ALD) that enables growth of inorganic materials inside polymer films and polymeric nanostructures (figure 1). Utilization of the polymer nanostructure as a three-dimensional “incubator” for inorganic materials growth not only adds degrees of freedom for the design and fabrication of nanostructures but can also be harnessed for creating hybrid organic-inorganic materials with synergic properties. While SIS is a promising process, there is still a gap in the fundamental understanding of diffusion and growth of inorganic materials within polymers and their evolution with time.

To shed light on the SIS mechanism, the growth of Al₂O₃ in various homopolymer films was studied. SIS was conducted in an ALD chamber with in-situ mass uptake monitoring using quartz crystal microbalance (QCM), followed by ex-situ SEM and TEM characterization. The mass uptake measurements showed an initial rapid growth, followed by a slower increase in mass. The strong correlation between the exposure time and mass growth which was observed in the rapid growth regime indicates a diffusion-limited growth within the polymer. Comparison between homopolymers showed similar time-growth trend but with different mass gain due to their dissimilar chemistry. The growth process as a function of polymer structure was studied on a block polymer (BCP) system including thorough comparison between growth kinetics in BCP vs homopolymer systems. This work provides a fundamental understanding that can pave the way to new hybrid organic-inorganic and inorganic 3D nanostructures.

 Figure 1: Schematic illustrations of the SIS process in (a) homopolymer and (b) block copolymer