Porous Layer-by-Layer Films Assembled Using Polyelectrolyte Blend to Control Wetting Properties

Abstract

Porous layer-by-layer (LbL) films have been employed for the implementation of superwetting surfaces, but they are limited to the LbL films consisting of only two oppositely charged polyelectrolytes. In this study, LbL films were assembled using a cationic polymer blend of branched poly(ethylene imine) (BPEI) and poly(allylamine hydrochloride) (PAH), and anionic poly(acrylic acid); they were then acid-treated at pH 1.8–2.0 to create a porous structure. The films of 100% BPEI exhibited a relatively smooth surface, whereas those of the 100% PAH exhibited porous surfaces. However, various surface morphologies were obtained when BPEI and PAH were blended. When coated with fluorinated silane, films with 50% and 100% PAH exhibited relatively higher water contact angles (WCAs). In particular, films with 50% PAH exhibited the highest WCA of 140–150° when treated at pH 1.8. These fluorinated films were further infused with lubricant oil to determine their feasibility as slippery surfaces. The water and oil sliding angles were in the range of 10–20° and 5–10°, respectively. Films prepared with the BPEI/PAH blend showed lower water slide angles than those prepared with 100% BPEI or PAH. Acid treatment of LbL films assembled using a polyelectrolyte blend can effectively control surface morphologies and can potentially be applied in superwetting.

Artificial Extracellular Matrix Composed of Heparin-Mimicking Polymers for Efficient Anticoagulation and Promotion of Endothelial Cell Proliferation

“… By increasing the number of layers, the thickness leveled off at six layers (Figure A) because the polymers on the surface were not assembled in regularly due to the structure with significant chain entanglements, which limited the layer to layer . Moreover, it was found that the polymer layer was thicker for CS than PEI because the relative molecular weights and space volumes of CS were greater than those of PEI Figure B shows that the thicknesses were independent of the components of GSAs.…”

“…27 Moreover, it was found that the polymer layer was thicker for CS than PEI because the relative molecular weights and space volumes of CS were greater than those of PEI. 28 Figure 2B shows that the thicknesses were independent of the components of GSAs. Figure 2C shows that the water contact angle of the modified surface decreased by 40−70°, indicative of the enhanced hydrophilicity of the modified surfaces.…”

“…The microscopic images of the modified surfaces displayed interpenetrating mesh structures (Figure 2E,F), relating to the chain entanglements that originated from the attractive interactions between the cationic and anionic polymers. 28 To further characterize the modified surfaces, their chemical structures were measured by FTIR. Compared to PVC, the single peak at 3375 cm −1 for GSAs/PEI LBL6 belonged to −OH and −NH (Figure 3A), the peak at 1623 cm −1 proved the presence of the C�O structure (−CO−NH−) in GSAs, and the single peak at 1026 cm −1 was a vibrational single peak of C−H (Ph).…”

Weak Polyelectrolytes as Nanoarchitectonic Design Tools for Functional Materials: A Review of Recent Achievements

“…Accordingly, swelling coefficients of, respectively, up to 5-fold and 8-fold were found for PLL/HA multilayers subjected to ionic strength [ 104 ] and pH [ 105 ] stimuli. The swelling process was accompanied by structural changes in multilayer films, such as the emergence of holes in PLL/HA films when the NaCl concentration was changed from 0.15 M to 0.48 M [ 105 ] and the growth of pores in (PEI/PAH)/PAA films after the post-assembly pH was decreased to pH 2 [ 106 ]. The potential of such porous coatings was tested for designing slippery liquid-infused porous surfaces [ 106 , 107 ].…”

“…The swelling process was accompanied by structural changes in multilayer films, such as the emergence of holes in PLL/HA films when the NaCl concentration was changed from 0.15 M to 0.48 M [ 105 ] and the growth of pores in (PEI/PAH)/PAA films after the post-assembly pH was decreased to pH 2 [ 106 ]. The potential of such porous coatings was tested for designing slippery liquid-infused porous surfaces [ 106 , 107 ]. Concurrently, the modulation of the mass transport properties of weak polyelectrolyte multilayer films by post-assembly treatment has attracted much attention [ 108 ], leading to systems with tailored functions ( Table 4 ), including ionic current rectification [ 109 ], enhanced Li + conductivity [ 110 ], and filtration [ 111 ].…”