Vapor Phase Infiltration: Sorption Thermodynamics, Chemical Entrapment Mechanisms, and Hybrid Material Structure-Property Relations

Vapor phase infiltration (VPI) creates hybrid organic-inorganic materials by infusing the sub-surface of polymers with vapor phase, metal containing precursors. These volatile materials are often then co-reacted with an oxidant to form a final state (commonly a metal oxide) that is incorporated within the polymer at the molecular to nanoscale level. The chemistries and processes used in VPI direct how the inorganic is included within the polymer and therefore dictate the hybrid material’s ultimate properties. Generally, the whole of the properties evoked via VPI are inaccessible by the organic and inorganic portions alone. In addition to nanoscale incorporation, VPI offers the advantage of leaving the macroscale form of the polymer unchanged, allowing for the post-fabrication modification of polymeric materials such as membranes, fabrics, etc. In this thesis, VPI is explored from a materials science and engineering perspective where characterizing the influence of processing parameters on material structure opens opportunities for new application spaces. Following an introduction to VPI and an assessment of the state of the art in VPI literature, this work explores the influence of VPI processing parameters (temperature, precursor exposure times, precursor dose pressures, etc.) and system chemistries on thermodynamic and kinetic principles. This exploration culminates in a proposed model for mathematically describing VPI processes that feature reactions between polymer functional groups and precursors. This knowledge is then employed to broaden the application space of VPI by studying how VPI can improve the solvent stability of both commodity polymers and polymer membranes. Finally, an exploration of the durability of the hybrid materials created via VPI is conducted. The work is concluded by looking into with future prospects and considerations for the VPI process.Ph.D