Polycaprolactone-based block copolymers for nanopatterning oxide materials via sequential infiltration synthesis.

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Sequential infiltration synthesis (SIS) integrates inorganic materials into polymer templates for nanostructure fabrication.
• Conventional SIS often uses polymers like block copolymers (BCPs), but biocompatible polymers remain underexplored for nanopatterning.
• Polycaprolactone (PCL) has not been previously investigated as a guiding polymer in SIS.

Purpose of the Study:

• To investigate the feasibility of using polycaprolactone (PCL) as a guiding polymer in sequential infiltration synthesis (SIS).
• To demonstrate the selective infiltration of aluminum oxide (Al2O3) into polystyrene-block-polycaprolactone (PS-b-PCL) block copolymers.
• To explore the tunability of SIS by varying cycles and temperatures for Al2O3 nanostructure formation.

Main Methods:

• Utilized sequential infiltration synthesis (SIS) with polystyrene-block-polycaprolactone (PS-b-PCL) block copolymers.
• Employed Fourier transform infrared (FTIR) spectroscopy to confirm precursor-polymer interactions.
• Used scanning electron microscopy (SEM) to characterize the resulting Al2O3 nanostructures after polymer removal.

Main Results:

• Confirmed strong interactions between TMA-H2O precursors and PCL's functional groups via FTIR.
• Revealed well-defined Al2O3 nanostructures using SEM post-SIS and polymer removal.
• Observed systematic control over inorganic content and nanostructural fidelity by adjusting SIS cycles and temperatures.
• Demonstrated significant Al2O3 incorporation in the first SIS cycle due to strong PCL-precursor interactions, even at 60 °C.

Conclusions:

• Polycaprolactone (PCL) is a promising guiding polymer for SIS, expanding beyond traditional polymers.
• The SIS process with PCL is efficient and relatively low-resource, with significant Al2O3 incorporation early in the process.
• This research opens new avenues for fabricating oxide nanostructures for applications in nanopatterning, dielectric layers, and biomaterials.