title: Preparation, characterization, and thermal gelation of amphiphilic alkyl-poly(ethyleneimine).
abstract: Amphiphilic alkyl-poly(ethyleneimine)s (alkyl-PEI) with different degrees of polymerization have been produced by alkaline hydrolysis of alkyl-poly(2-methyl-2-oxazoline). Potentiometric titration of the alkyl-PEI shows the influence of the alkyl chain and the degree of polymerization on the titration curves and hence on the polymer conformation. Karl Fischer titration has been used to determine the water content in the polymers. Subsequent X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) measurements prove the existence of different hydration states of the PEI even under dry storage conditions. Upon cooling from hot aqueous solutions, hydrogels form. The gelation concentration decreases with increasing degree of polymerization of the PEI segment. Scanning electron microscopy (SEM and cryo-SEM) of the hydrogels reveal an alkyl-PEI fibrous network composed of fan-like units. DSC shows that the percentages of bound and free water in the hydrogels depend on the concentration of polar amino groups.
authors.affiliation: Institute of Technical Chemistry, Department of Macromolecular Chemistry, Braunschweig University of Technology, Hans-Sommer-Strasse 10, D-38106 Braunschweig, Germany.
authors.forename: Salvador
authors.initials: S
authors.lastname: Navarro
authors.forename: Andriy
authors.initials: A
authors.lastname: Shkilnyy
authors.forename: Brigitte
authors.initials: B
authors.lastname: Tiersch
authors.forename: Andreas
authors.initials: A
authors.lastname: Taubert
authors.forename: Henning
authors.initials: H
authors.lastname: Menzel