Effect of Primary vs Secondary Amines on the Reactivity and Dynamics of CO2 in Polyallylamine Sorbents under Humid Conditions
Authors: Avery E. Baumann, Alice Klapproth, Richard A. Mole, Craig M. Brown, Christopher M. Stafford, Christopher L. Soles
Journal: ACS Appl. Polym. Mater.
Abstract:
Selective facilitated transport membranes are viable technologies for separating dilute CO2 from mixed-gas streams. In this study, we measure the reactivity and transport behavior of two polyallylamine amine polymers that bind CO2 in humid environments. We quantify sorption of CO2 and water components using a tandem quartz crystal microbalance mass sensor coupled with infrared spectroscopy for chemical identification of the sorbed gases and their reaction products. The two high-molecular-mass (glassy) polyallylamine materials, one containing just primary amines and the other containing isopropyl-functionalized secondary amines, react with humid CO2 to form tethered carbamate/carbamic acid groups or bicarbonate ions, respectively. Because our technique allows for the discernment of specific water and CO2 uptake, we also identify that the different reactivities influence the sorbed water content in the polymer films. We further quantify the local or segmental mobility of the dosed polymers with quasielastic neutron scattering measurements on the few nanoseconds to tens of picoseconds time scales, revealing that a classic jump diffusion model describes the dynamics of the polymers and their polymer–sorbate complexes. The resulting jump lengths and residence time between jumps differ based on the polymer chemistry and dosing conditions, with the hindered secondary amine systems generally presenting longer residence times and slightly longer jump distances. This combination study featuring both quasielastic neutron scattering and tandem gravimetric and chemical uptake measurements adds to the broader understanding of amine polymer dynamics and reactivity in CO2 capture applications.
The ability of bacterial pathogens to colonise indwelling medical devices, particularly urinary catheters, and to establish drug-resistant biofilms accounts for approximately 60 % of all nosocomial infections, underscoring the urgent need for effective strategies to mitigate biofilm development on catheter surfaces. In this study, we developed a multilayer nano-composite coating for urinary catheters, assembled via sequential deposition of bioadhesive catechol-functionalised chitosan (catCS), hyaluronic acid (HA), and antimicrobial aminated lignin nanoparticles (N-LigNPs). Sono-enzymatically phenolated, aminated, and formulated lignin nanoparticles (NPs) served as both structural and functional components within the coatings, whose assembly was monitored in real time using a quartz crystal microbalance with dissipation. Atomic force microscopy was employed to characterise the coating topography, complemented by surface zeta potential measurements and lubricity analysis. Cross-linking of N-LigNPs with catCS, catalysed by the oxidative enzyme laccase, increased the mechanical integrity of the coating beyond that afforded by electrostatic interactions alone. This translated into durable antimicrobial and antibiofilm performance of the functionalised catheters over 7 days in a hydrodynamic model simulating a catheterised human bladder, reducing S. aureus and Escherichia coli biofilm formation by more than 60 %, while exhibiting no cytotoxic effects on mammalian cells. Moreover, the clinical, histological, and microbiological data obtained from in vivo studies in a rabbit model demonstrated that the coating was biocompatible and effectively prevented catheter-associated urinary tract infections during a 10-day indwelling period.
Abstract: 
