On the Differences in Trimethylaluminum Infiltration into PMMA and PLA Polymers for Sequential Infiltration...

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Sequential infiltration synthesis (SIS) is a method for templated material growth.
• Trimethylaluminum (TMA) infiltration into polymers to grow Al2O3 has been studied.
• Atomic-level details of TMA infiltration into different polymers remain unclear.

Purpose of the Study:

• Investigate Al2O3 infiltration into poly(methyl methacrylate) (PMMA) and poly(lactic acid) (PLA) using SIS.
• Elucidate the molecular-level mechanisms behind differential TMA infiltration and polymer swelling.
• Combine experimental and theoretical approaches to understand SIS complexities.

Main Methods:

• Sequential infiltration synthesis (SIS) in an ALD reactor at 70 °C using TMA and water.
• Operando spectroscopic ellipsometry and ex-situ X-ray photoelectron spectroscopy (XPS) for material analysis.
• First-principles density functional theory (DFT) calculations for theoretical modeling.

Main Results:

• Al2O3 incorporation is significantly higher in PLA than in PMMA.
• TMA infiltration occurs via Al-O covalent bond formation at the C-O-C group in both polymers.
• PLA exhibits greater swelling upon TMA infiltration compared to PMMA, explained by more exothermic TMA-polymer interactions.

Conclusions:

• The study provides a molecular-level understanding of TMA infiltration and swelling in PMMA and PLA.
• Differences in TMA infiltration and swelling are attributed to the exothermic interaction strength between TMA and the polymer's C-O-C group.
• The combined experimental and theoretical approach offers a toolkit for analyzing SIS processes.