Structural analysis of poly(amidoamine) dendrimer immobilized in crosslinked poly(ethylene glycol)

Abstract

Polymeric membranes comprised of poly(amidoamine) (PAMAM) dendrimer immobilized in a poly(ethylene glycol) (PEG) network exhibit an excellent CO 2 separation selectivity over H 2 . The CO 2 permeability increases with PAMAM dendrimer concentration in the polymeric membrane and becomes 500 times greater than H 2 permeability when the dendrimer content was 50 wt % at ambient conditions (5 kPa of CO 2 partial pressure). However, the detailed morphology of the membrane has not been discussed. The immiscibility of PAMAM dendrimer and PEG matrix results in phase separation, which takes place in a couple of microns scale. Especially, laser scanning confocal microscope captures a 3D morphology of the polymeric blend. The obtained 3D reconstructions dem-onstrate a bicontinuous structure of PAMAM dendrimer-rich and PEG-rich phases, which indicates the presence of PAMAM dendrimer channel penetrating the polymeric membrane, and CO 2 will preferentially pass through the dendrimer channel. In addition, Fourier transform of the 3D reconstructions indicates the presence of a periodic structure. An average size of the dendrimer domain calculated is 2-4 lm in proportion to PAMAM dendrimer concentration.

A compatible crosslinker for enhancement of CO2 capture of poly(amidoamine) dendrimer-containing polymeric membranes

“…Photopolymerization without 4GMAP gives an opaque polymeric membrane due to the polymerization-induced macrophase separation between PAMAM dendrimer and PEG matrix as represented in Fig. 4a [16]. On the contrary, incorporation of 4GMAP results in the formation of a macroscopically transparent membrane in Fig.…”

“…A ratio of solutes to ethanol is 2.0 by wt, and a monomer to initiator ratio is 60 by mol. For a laser scanning confocal microscope (LSCM) observation, FITC-PEGMA [16] is incorporated into the photocopolymerization with 1 wt% relative to the monomers. The dendrimer concentration is 50 wt%.…”

“…The polymerization-induced phase separation is examined on a LSM 710 laser scanning confocal microscope (Carl Zeiss, Germany) with an incident laser beam (488 nm) [16]. A band-pass filter (490-735 nm) installed in front of the detector is used to detect only fluorescence from the fluorescent molecules that are introduced only to stain the PEG-rich phase.…”

“…However, recent intensive investigations of the dendrimer-containing membranes reveal the formation of a bicontinuous structure of PAMAM dendrimer-rich and PEG-rich phases upon photopolymerizationinduced phase separation on a couple of microns scale [16]. When the membrane thickness is less than 200 μm, the resulting membrane loses the high CO 2 separation properties over H 2 because leakage of the physically entrapped dendrimer from the membrane is not negligible.…”

CO2 Separation with Nano-thick Polymeric Membrane for Pre- combustion

“…Recently, facile immobilization of PAMAM dendrimers in a crosslinked PEG is reported by photopolymerization of PEG dimethacrylate in the presence of the dendrimers [6]. The obtained polymeric membranes are not transparent due to phase separation on a couple of microns scale between PAMAM-rich and PEG-rich phases [7]. While the polymeric membranes show excellent CO 2 separation properties over H 2 , CO 2 permeance should be elevated for use.…”