Short versus long chain polyelectrolyte multilayers: a direct comparison of self-assembly and structural properties

Micciulla, Samantha; Dodoo, Samuel; Chevigny, Chloé; Laschewsky, André; Klitzing, Regine von

doi:10.1039/c4cp03439b

Cited by 27 publications

(29 citation statements)

References 71 publications

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“…The central and inner regions, instead, show only small changes corresponding to a slight shift of the 4L film structure away from the substrate. In general, water shows a profile antithetic to the one of OEs, with a significantly lower density in the central region of the film, as has been established in several experimental works 64,95,96 . Consequently, the sloppy structure of the multilayer can be attributed to the strong hydration of the silica surface, which hinders the adsorption of OEs.…”

Section: Overall Density Profiles and Water Uptakesupporting

confidence: 66%

“…We can see that the values corresponding to the pair PDADMAC-N + /PSS-S − are significantly larger than for any other pair, confirming the dominance of the intrinsic charge compensation in all OEMs. These values also confirm that such intrinsic compensation is slightly lower for 4L systems, in contradiction with the general higher intrinsic compensation of PSS ended PEMs and OEMs postulated indirectly from experimental observations 64 . However, this contradiction might be partially alleviated when one observes that PSS-S − has also a lower ex-trinsic compensation in 4L than PDADMAC-N + in 3L, which is a behavior specifically observed experimentally in analogous PEM systems 91 .…”

Section: Charge Pairingcontrasting

confidence: 50%

“…This is an unexpected result, since the short length of these OE chains can not favor strong entanglements in the system. Additionaly, this lack of order in the internal structure of OEMs contradicts, in principle, the hypothesis of a structure of well defined flat layers that was made in reference 64 for these systems. Such hypothesis was based on the experimental measurements of the mechanical properties of the films and the structural model proposed in reference 100 .…”

Section: Oes Layering: Center-of-mass Distributionsmentioning

confidence: 77%

“…Briefly, we simulate the growth of a PDAD-MAC/PSS tetralayer by LbL deposition from water solutions of oligoelectrolytes with a degree of polymerization of DP = 30 monomers and a concentration of 0.1M of monovalent added salt. The use of added salt has been proven experimentally to be essential for the formation of a stable multilayer when so short PE chains are employed 64 . Both, counter-ions and added salt ions, are Na + and Cl − .…”

Section: Pdadmac/pss Oe Tetralayermentioning

confidence: 99%

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Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

et al. 2019

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By employing large-scale molecular dynamics simulations of atomistically resolved oligoelectrolytes in aqueous solutions, we study in detail the first four layer-by-layer deposition cycles of an oligoelectrolyte multilayer made of poly(diallyl dimethyl ammonium chloride)/poly(styrene sulfonate sodium salt) (PDADMAC/PSS). The multilayers are grown on a silica substrate in 0.1M NaCl electrolyte solutions and the swollen structures are then subsequently exposed to varying added salt concentration. We investigated the microscopic properties of the films, analyzing in detail the differences between three-and four-layers systems. Our simulations provide insights on the early stages of growth of a multilayer, which are particularly challenging for experimental observations. We found a rather strong entanglement of the oligoelectrolytes, with a fuzzy layering of the film structure. The main charge compensation mechanism is for all cases intrinsic, whereas extrinsic compensation is relatively ehanced for the layer of the last deposition cycle. In addition, we quantified other fundamental observables of these systems, as the film thickness, water uptake, and overcharge fractions for each deposition layer.

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Section: Overall Density Profiles and Water Uptakesupporting

confidence: 66%

Section: Charge Pairingcontrasting

confidence: 50%

Section: Oes Layering: Center-of-mass Distributionsmentioning

confidence: 77%

Section: Pdadmac/pss Oe Tetralayermentioning

confidence: 99%

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Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

et al. 2019

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“…For linear growth behavior, the film thickness increased with the increase of molecular weight of polyelectrolytes because of the more coiled polyelectrolyte chains with high molecular weight. [19,29] However, with the existence of interlayer diffusion, the film thickness increased with the decrease of the molecular weight of polyelectrolytes, indicating a fast diffusion of low molecular weight polyelectrolytes. [30,31] For hyaluronan (HA)/chitosan (CHI) multilayers [32], in which CHI is the diffusing polyelectrolyte and HA is the non-diffusing species, the film thickness increased with the molecular weight increase of both polyelectrolytes.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and interlayer diffusion controlled growth and unique surface patterned growth of polyelectrolyte multilayers

Meharg

Lee

2017

Polymer

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In this work, extremely high molecular weight (M w ) poly(allylamine hydrochloride) (PAH, 900K g/mol) and poly(acrylic acid) (PAA, 225 K g/mol) were selected to amplify the difference in the growth of multilayers in comparison with low M w PAA (15K g/mol) and PAH (15K g/mol). By varying the pH conditions, the PAH/PAA multilayers were fabricated via the layerby-layer (LbL) assembly in both linear and exponential growth regimes. In the linear growth regime with interlayer diffusion suppressed, high M w polyelectrolytes with low charge density could slow down the adsorption step, leading to the decrease of thickness compared to low M w polyelectrolytes when the deposition time was limited. However, the effect of M w could be reversed by increasing the deposition time, for the adsorption of low M w polyelectrolyte reached equilibrium, while the adsorption of high M w polyelectrolyte continued. The larger coil size of high M w polyelectrolyte could enable the surpassing of multilayer thickness compared with low M w polyelectrolyte. In the exponential growth regime, besides the slow adsorption, the application of high M w polyelectrolytes further suppressed the interlayer diffusion, leading to the decrease of multilayer thickness regardless of deposition time. We further studied the effects of deposition time, M w of polyelectrolytes, and the number of bilayers on the surface morphology in the exponential growth regime. Surface roughness significantly increased with the application of © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 high M w PAA and the increase in deposition time. For the first time, the unique LbL film growth patterns of islet, ring and cantaloupe skin-like structures that consecutively formed on the surface of polyelectrolyte multilayers were reported by tuning the above parameters.

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Design of Porous Alginate Hydrogels by Sacrificial CaCO₃ Templates: Pore Formation Mechanism

Sergeeva

Feoktistova

Prokopović

et al. 2015

Adv Materials Inter

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signifi cantly precise control over the scaffold architecture. Well-defi ned internal structure (porosity) determines both cellular infi ltration into the scaffold and its material properties. Pore size and distribution ensuring diffusion of nutrients into the scaffold and removal of metabolic products is of high importance. [ 4,11 ] Ionically crosslinked polymer gels such as alginate hydrogels have been extensively developed as scaffolds for tissue engineering. [12][13][14][15] The adjustable kinetics of the alginate gel degradation at neutral pH [ 1,16,17 ] gives an option to use the gels for multiple applications as wound dressings, anti-adhesive, and repair materials. [ 14,[18][19][20][21] Characteristics of alginate gels (hydration, softness, porosity, swelling in water, etc.) can be adjusted using a certain fabrication approach and by variation of interactions between charged polyanionic groups and crosslinking counterions; [ 13,17,[22][23][24][25] these interactions are known to be strongly affected by ionic strength, molecule length and structure, solvent pH, salt concentration, and temperature conditions. [26][27][28][29][30][31] This allows the fabrication of alginate scaffolds possessing desired properties corresponding to a certain tissue, for instance cartilage, [ 12 ] or dura mater. [ 21 ] Porous alginate gels can provide space and mechanical support to seed biological cells for tissue formation, [ 1,13,32 ] also allowing a controlled release of gel-laden drugs (peptides and proteins) trapped within the alginate network. [ 14,24,25,33,34 ] To achieve loading of both biological cells and bioactive molecules, the internal structure of hydrogels has to be controlled on the scale of nano-and micrometers. Adjustment of the gel geometry has been demonstrated on substrate surfaces using different micropatterning techniques including a light-addressable electrolytic system, [ 14 ] electrodeposition, [ 15 ] electrochemical patterning, [ 35 ] or the benchtop method using Nylon mesh. [ 11 ] The internal structure of alginate gels has been patterned with regular tube-like pores, [ 16,36 ] interconnected ordered honeycomb pores, [ 12 ] and sponge-like isotropic pores. [37][38][39] However, most of the approaches for alginate gel fabrication lack a precise control over the microstructure and require special equipment. Encapsulation of molecules of interest with controlled spatial distribution is rather complicated or even impossible. There is a need to develop a simple approach for design of a scaffold with welldefi ned internal structure providing both a space to culture cells and cavities to host/release encapsulated (bio)active molecules.Fabrication of porous alginate hydrogels with a well-controlled architecture useful for tissue engineering is still a challenge. Here, CaCO 3 -based templating is utilized to design stable alginate gels with controlled pore dimensions in the range of 5-50 µm. The mechanism of pore formation is studied considering two factors affecting the pore size: i) osmotic pressure generat...

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Short versus long chain polyelectrolyte multilayers: a direct comparison of self-assembly and structural properties

Cited by 27 publications

References 71 publications

Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

Adsorption and interlayer diffusion controlled growth and unique surface patterned growth of polyelectrolyte multilayers

Design of Porous Alginate Hydrogels by Sacrificial CaCO₃ Templates: Pore Formation Mechanism

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Short versus long chain polyelectrolyte multilayers: a direct comparison of self-assembly and structural properties

Cited by 27 publications

References 71 publications

Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

Atomistic simulation of PDADMAC/PSS oligoelectrolyte multilayers: overall comparison of tri- and tetra-layer systems

Adsorption and interlayer diffusion controlled growth and unique surface patterned growth of polyelectrolyte multilayers

Design of Porous Alginate Hydrogels by Sacrificial CaCO3 Templates: Pore Formation Mechanism

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Design of Porous Alginate Hydrogels by Sacrificial CaCO₃ Templates: Pore Formation Mechanism