Response of Swelling Behavior of Weak Branched Poly(ethylene imine)/Poly(acrylic acid) Polyelectrolyte Multilayers to Thermal Treatment

Abstract

Weak polyelectrolyte multilayers (PEMs) prepared by the layer-by-layer technique have attracted a great deal of attention as smart responsive materials for biological and other applications in aqueous medium, but their dynamic behavior as a function of exposure to a wide temperature range is still not well understood. In this work, the thermally dependent swelling behavior of PEMs consisting of branched poly(ethylenimine) and poly(acrylic acid) is studied by temperature controlled in situ spectroscopic ellipsometry. Because of diffusion and interpenetration of polyelectrolytes during film deposition, the PEMs densify with increasing bilayer number, which further affects their water uptake behavior. Upon heating to temperatures below 60 °C, the worsened solvent quality of the PEM in water causes deswelling of the PEMs. However, once heated above this critical temperature, the hydrogen bonds within the PEMs are weakened, which allows for chain rearrangement within the film upon cooling, resulting in enhanced water uptake and increased film thickness. The current work provides fundamental insight into the unique dynamic behavior of weak polyelectrolyte multilayers in water at elevated temperatures.

Effect of anionic surfactant on alginate‐chitosan polyelectrolyte multilayer thickness

“…As seen from Figure 2, n values are smaller for films with PEMs from 5 to 10 double layers and the change is faster for the earlier number of double layers. 36 In this case, the changes in refractive indices between 6 and 12 double layers were 0.02 and 0.03 for alginate-terminated PEMs without and with SDS, respectively. After 12 double layers, the refractive indices remained almost constant.…”

“…As seen from Figure , n values are smaller for films with SDS. The aricle by Gu et al shows a change of ≈0.05 in refractive index of poly(ethyleneimine)/poly(acrylic acid) PEMs from 5 to 10 double layers and the change is faster for the earlier number of double layers . In this case, the changes in refractive indices between 6 and 12 double layers were 0.02 and 0.03 for alginate‐terminated PEMs without and with SDS, respectively.…”

Cephalopods-Inspired Rapid Self-Healing Nanoclay Composite Coatings with Oxygen Barrier and Super-Bubble-Phobic Properties

“…The doublet peak is attributed to the intermolecular and intramolecular hydrogen bonds originating from the COOH of PAA. 46 Hence, the ion doping suppressed the dissociation of the carboxyl groups and the hydrogen bonding appeared stronger, while the addition of MMT suppressed the hydrogen bonding, suggesting that MMT was deposited on the bPEI along with PAA. This result is consistent with the previous discussion on film thickness, where the increase in MMT inhibits the network between and within polymer molecules, thereby suppressing the increase in film thickness.…”

Ordered polymer composite materials: challenges and opportunities

“…128,161 Modulation of these structures and thus the material properties can even be modified post-fabrication via the introduction of stimuliresponsive moieties. 19,[162][163][164][165][166][167][168] Hammond and coworkers, for example, reported the electrostatic LBL assembly of cationic linear poly(ethyleneimine) (LPEI) and anionic prussian blue (PB) NPs into lamellar films with the ability to undergo redox-driven film swelling ( Figure 7). 169 Film swelling was driven by electrochemical reduction of the redox-active PB NPs, resulting in migration of water and counterions into the film (Figure 7b).…”