Nano- and Microporous Layer-by-Layer Assemblies Containing Linear Poly(ethylenimine) and Poly(acrylic acid)

Lutkenhaus, Jodie L.; McEnnis, Kathleen; Hammond, Paula T.

doi:10.1021/ma800003x

Cited by 96 publications

(101 citation statements)

References 65 publications

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“…The reason is that the film peeled off from the substrate after 30 min HCl post-treatment. Recently, similar optical microscopy experiments have been performed by Lutkenhaus et al [24]. The micro-scale pores are also observed in the post-treatment of PEI/PAA multilayer film with acid solution.…”

Section: Fesem Afm and Optical Microscopy Experimentssupporting

confidence: 74%

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The salt-, pH- and oxidant-responsive pervaporation behaviors of weak polyelectrolyte multilayer membranes

Wang

Zhang

et al. 2010

Journal of Membrane Science

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a b s t r a c tThe layer-by-layer (LbL) assembled polyelectrolyte multilayer has recently been recognized as a new class of promising membrane material for various separation uses. However, there is a lack of understanding about the influences of separation mixtures on the adsorbed polyelectrolytes. Therefore, clear understanding on it would be very important for the design and application of a type of new functional composite membrane. In this paper, the multilayer of weak polyelectrolytes polyethyleneimine and polyacrylic acid was constructed onto a hydrolyzed hollow fiber polyacrylonitrile support membrane under a negative pressure condition. The salt-, pH-and oxidant-responsive pervaporation behaviors of polyelectrolyte multilayer membranes were evaluated by post-treating with sodium chloride, hydrochloric acid, sodium hydroxide and sodium hypochlorite aqueous solutions, respectively. The pervaporation performances for separation of ethanol/water were compared before and after post-treatments. Scanning electron microscopy and atomic force microscopy confirmed the microtopographical changes of membrane surfaces. Optical microscopy was also used to real-time observe surface morphologies of polyelectrolyte multilayers deposited on the quartz substrates. Finally, the comparison of zeta potential values of inner surface before and after post-treatment also demonstrated the changes of surface electrical property.

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Section: Fesem Afm and Optical Microscopy Experimentssupporting

confidence: 74%

“…3. After post-treating with NaClO solution, the characteristic peaks at 1555 and 1401 cm −1 , which were due to the -COO − group [24,36,37], sharply weakened. As a comparison, the peak at 1732 cm −1 attributed to the -C O group became much stronger [11,38].…”

Section: Effects Of Different Post-treatment Conditionmentioning

confidence: 99%

The salt-, pH- and oxidant-responsive pervaporation behaviors of weak polyelectrolyte multilayer membranes

Wang

Zhang

et al. 2010

Journal of Membrane Science

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“…17 Recently, attention has been paid to the asymmetric properties, such as wettability and morphology, for the two surfaces of free-standing films. Lutkenhaus and co-workers 24 fabricated an asymmetric membrane with a fine porous skin layer and a thick microporous underlying layer via acidic postassembly treatment of a linear poly(ethylene-imine)/PAA (LPEI/PAA) multilayer. The same authors 25 also pointed out the possibility of constructing free-standing films with asymmetric wettability just after detachment of Poly(ethylene oxide)/PAA (PEO/PAA) LBL multilayer from substrates.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Free-Standing Film with Multifunctional Anti-Bacterial and Self-Cleaning Properties

Shen

Wang

et al. 2012

ACS Appl. Mater. Interfaces

131

100

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A superhydrophobic/hydrophilic asymmetric free-standing film has been created using layer-bylayer assembly technique. Poly(ethylene-imine)-Ag + complex (PEI-Ag + ) at pH 9.0 was assembled with poly(acrylic acid) (PAA) at pH 3.2 on a Teflon substrate to yield a micro-nanostructured surface that can be turned to be superhydrophobic after being coated with a low surface energy compound. Silver nanoparticle loaded free-standing film with one surface being superhydrophobic while the other surface is hydrophilic was then obtained after detachment from the substrate. The superhydrophobicity enabled the upper surface with anti adhesion and self-cleaning properties and the hydrophilic bottom surface can release silver ions as antibiotic agent. The broad-spectrum antimicrobial capability of silver ions released from the bottom surface coupled with superhydrophobic barrier protection of the upper surface may make the free-standing film a new therapy for open wound.

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“…(2) Liquid-liquid phase separation (demixing) occurs, and the crystallization proceeds in the higher polymer content phase (or possibly the polymer content in this phase is so high that it is almost amorphous solid state). Which of the above mechanisms (1) and (2) is preferred is determined by the interplay of the demixing and crystallization processes, which may depend on polymer-solvent interactions, interface free energy, mobility of the polymer chains, solvent viscosity, etc. From the presently observed morphologies we speculate that in DEP and TP solutions, direct crystallization from the solution occurs, and that in DMF and DMSO, the interplay of the crystallization and phase separation occurs.…”

Section: Resultsmentioning

confidence: 99%

Formation of Porous Spherulites of Poly(L-lactide) Grown from Solutions

2009

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Porous soft materials possessing high surface to volume ratio have been attracted much attention because of their potential applications such as functional filters, catalyst, and biomedical materials. Various techniques to fabricate materials with high porosity have been developed up to the present, which utilize the layer-by-layer deposition, 1 freeze-drying, 2 electro-spinning, 3 etc. In addition, crystallization of polymers from suitable solutions is another potential technique to obtain porous materials as small particles. Very porous particles of polyamide and poly(ethylene oxide) (PEO) have been obtained via spherulitic growth in solutions. 4,5 Such characteristic feature of morphology seems to be closely related to complicated mechanisms specific to solution crystallization. We have studied the mechanism of solution crystallization especially in viscous solvents, and have revealed an unusual diffusion aspect for isotactic polystyrene/viscous solvent systems.6 Another important feature of solution crystallization is that polymer-solvent interaction plays an important role, which is responsible for the resulting crystalline morphology. For example, crystallization of PEO in a very viscous solvent results in highly swollen spherulites with solvent, while in dimethyl sulfoxide crystallites with outer polygonal contours are formed suggesting that liquid-liquid phase separation occurs during the crystallization. For many biomedical applications of the porous materials, biocompatibility and biodegradability is usually required. In this respect, poly(L-lacide) (PLLA) is one of the most promising materials for the fabrication of porous particles by the solution crystallization method. It has been shown that single crystals of PLLA are formed from very dilute solutions, and their structure has been well characterized. 8,9 On the other hand, spherulites of PLLA are generally formed from more concentrated solutions and from melt.8,10 Porous PLLA fibres can be obtained by precipitation in a non-solvent under stirring. 11In this paper, we investigate the morphology of very porous PLLA particles which are obtained by solution crystallization. We employed four solvents with different viscosities, i.e., diethyl phthalate (DEP), glycerol tri-n-propionate (TP), N,Ndimethylformamide (DMF), and dimethyl sulfoxide (DMSO). Porous spherulites exhibiting remarkable morphology of a flower-like appearance (assembled petals) are successfully obtained especially from viscous solvents (DEP and TP). EXPERIMENTAL PLLA (M w ¼ 210 kg molÀ1 ) was supplied from Mitsui Chemicals Co., which contained 98% L units. The four solvents (DEP, TP, DMF, and DMSO) were distilled under reduced pressure before use. Table I shows viscosity of the solvents at 25 C. PLLA was added to each solvent in a glass tube and heated at 150 C for 15-30 min to make an apparently homogeneous solution of which the PLLA content was 5.0 wt %. Then, the sample tube was rapidly immersed in a water bath, where the temperature was controlled at 25, 30, and 35 C, and the tempe...

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Nano- and Microporous Layer-by-Layer Assemblies Containing Linear Poly(ethylenimine) and Poly(acrylic acid)

Cited by 96 publications

References 65 publications

The salt-, pH- and oxidant-responsive pervaporation behaviors of weak polyelectrolyte multilayer membranes

The salt-, pH- and oxidant-responsive pervaporation behaviors of weak polyelectrolyte multilayer membranes

Asymmetric Free-Standing Film with Multifunctional Anti-Bacterial and Self-Cleaning Properties

Formation of Porous Spherulites of Poly(L-lactide) Grown from Solutions

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