Committee Members:

Prof. Mark Losego, Advisor, MSE

Prof. Ryan Lively, ChBE

Prof. Faisal Alamgir, MSE

Controlling Inorganic Loading in Polymer of Intrinsic Microporosity 1 with Vapor Phase Infiltration Vapor Pressure, Exposure Time, and Precursor Chemistry

Abstract:

Vapor phase infiltration (VPI) is a post-polymerization modification method for infusing inorganic clusters into a polymer to create organic-inorganic hybrid materials with properties unique from the parent polymer. The properties of these hybrid materials can vary with the amount of VPI generated inorganic loading. However, because mass uptake during VPI consists of both entrapped species as well as species that are dissolved within the polymer, the relationship between VPI processing conditions and the VPI mass uptake is still not fully understood. In this thesis, the effects of precursor-polymer compatibility as well as VPI dose pressure and exposure time on the final VPI generated inorganic loading is explored using the technologically relevant membrane material polymer of intrinsic microporosity 1 (PIM-1). To understand the differences in inorganic loading, experimentally observed variations in precursor chemistry, are compared with density functional theory (DFT) calculated precursor-to-polymer binding energies. Inorganic loading is found to correlate with higher binding energy complexes. Moreover, inorganic loading can be controlled with both precursor vapor pressure and exposure time at sufficiently low dose pressures and infiltration times (i.e., before saturation). However, inorganic loading appears to saturate for this system when the polymers functional groups become fully populated with bound VPI precursors. This means that at higher pressures, the inorganic loading is not necessarily increased, however the kinetics get faster. These experimental results can be understood with the use of a recently developed reaction-diffusion model for VPI. Critical to applying this model to these post-deposition measurements is re-normalizing the reaction-diffusion model calculated mass loading to the total number of functional groups in the polymer. Lastly, this thesis provides a framework to describe VPI mass uptake kinetics using purely ex-situ measurement techniques.