Comprehensive Analysis of Crystalline Hydrophobic Alkylated Poly(ethyleneimine)s

Polyethyleneimine (PEI) is a widely used polymer in catalysis, gas separation, water treatment, drug delivery, textile, and paper production. We propose a new method of transforming hydrophobic and hygroscopic PEIs into hydrophobic and crystalline materials via simple alkylation. The crystalline structure of the alkylated PEIs was characterized using powder X-ray diffraction, small-angle X-ray scattering, thermogravimetric analysis, and inelastic neutron scattering. Consequently, the amine-rich alkylated polymer demonstrates CO2 responsiveness for CO2-mediated desalination.