Functionalized Polymers containing Quaternary Ammonium Cation for Ultrafine Aerosol Filter and Ion Exchange Membrane

Abstract

This thesis considers functional polymers containing a quaternary ammonium moiety to obtain a performance with durability in ultrafine aerosol filter and anion exchange membrane. Quaternary ammonium compounds (QACs) have characteristics including a high dipole moment, polar, and hydrophilic due to a separated charge. Owing to those characteristics, QACs utilized for an anion exchange, intermolecular interactions, and antibacterial activity. The aim of first study was to fabricate a highly durable functionalized polymer filters (FPFs) to capture the ultrafine aerosols even it treated through a water or IPA. Functionalized polymer filters (FPFs) were fabricated using a synthesized terpolymer containing a quaternary ammonium moiety via electrospinning. FPFs showed the best performance than others, and the removal efficiencies were over 90% when the sodium chloride aerosol were sized in 100 to 300 nm, respectively. In addition, FPFs had almost no decrease in the removal efficiency after the treatment by isopropyl alcohol (IPA). On the other hand, the IPA-treated PS and electret filter showed the rapid decrease to 49.0% from 78.2% for the sodium chloride aerosol. Furthermore, FPF1 also showed good antibacterial activity, a desirable characteristic for using the air filter without infections. Second research was about synthesis and characterization of anion exchange membrane for a better alkaline stability. Functionalized polymers (QPX) were synthesized with long side chain, and a quaternary ammonium groups are attached at the end of the side chain to reduce the degradation. Crosslinked QPX (cQPX) was also prepared to remain cations well against alkaline condition. QPXa and cQPXb showed a good thermal stability over 200 oC, which is enough to operate in alkaline fuel cell system. Dimensional stability of the membranes was also measured, and the results showed not only absorbing water but also managing well. cQPHc observed the best anion conductivity, 0.105 mS/cm at 80 oC. When the chain length was same, crosslinked membranes showed better anion conductivity than those of non-crosslinked ones. cQPH almost kept its performance of anion conductivity from 105 to 92 mS/cm at 80 oC even after it soaked into 1 M NaOH during 16 days.