Micropatterning and Impedance Characterization of an Electrically Percolating Layer‐by‐Layer Assembly

Everett, W. Neil; Jan, C. Jason; Sue, Hung‐Jue; Grunlan, Jaime C.

doi:10.1002/elan.200603811

Cited by 7 publications

(4 citation statements)

References 40 publications

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“…Typical BL thicknesses range from 1 to 100 nm, depending on factors that include chemistry , molecular weight , temperature , , counterions , ionic strength , and pH , . A variety of LbL-assembled functional thin films are currently being evaluated for properties that include antimicrobial , , antireflection , electrochromic − , sensing − , oxygen barrier , and biomedical applications . In many cases, solid nanoparticles, such as clay − , are one type of the charged species imparting a desired property.…”

Section: Introductionmentioning

confidence: 99%

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Schulz

Grunlan

2009

ACS Appl. Mater. Interfaces

176

115

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Thin composite films of branched polyethylenimine (BPEI) and Laponite clay platelets were prepared using layer-by-layer assembly. The film thickness was tailored by altering the pH of the aqueous mixtures used to deposit these films, resulting in growth that ranged from 0.5 to 5 nm/bilayer (BL). High-pH BPEI and low-pH clay produced the thickest films. The microstructure of tilted Laponite clay platelet stacks is observed with transmission electron microscopy when using unadjusted BPEI (pH 10.3) and pH 6 Laponite. This recipe resulted in a film with 83 wt % clay and a hardness of 0.5 GPa. In all films, the clay platelets are uniformly deposited and look analogous to a cobblestone path in atomic force microscopy surface images. Several 40-BL films, with thicknesses of 100 nm or more, exhibit reduced moduli ranging from 7 to 10 GPa and hardness of around 0.5 GPa, suggesting that these transparent films could be useful as hard coatings for plastic films. These thin coatings were also deposited onto cotton fabric. Each individual cotton fiber was uniformly coated, and the fabric has significantly more char left after burning than the uncoated fabric. Thermogravimetric analysis results reveal that fabric coated with 10 BLs of BPEI/Laponite produces up to 6 wt % char at 500 degrees C, which is almost 1 order of magnitude greater than that of untreated fabric. This initial study demonstrates that polymer/clay assemblies could improve the thermal stability of cotton and may be useful for fire safety applications.

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Section: Introductionmentioning

confidence: 99%

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Schulz

Grunlan

2009

ACS Appl. Mater. Interfaces

176

115

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“…Electrostatic interactions are not the only intermolecular binding force used for assembly, as these multilayered films have been assembled via hydrogen bonding, , donor/acceptor interactions, and covalent bonds. , Formulation and process conditions such as chemistry of the layer components, , counterions, molecular weight, ionic strength, and pH , of the dipping solutions/mixtures, and temperature, , can influence BL thickness, which typically ranges from 1−100 nm. Recent studies on a variety of LbL films highlight a diverse and useful set of properties that include antimicrobial, , antireflection, and electrochromic, − as well as potential applications ranging from drug delivery, to oxygen barrier, to sensors. − In many cases it is the presence of nanoparticles within the film, such as clay, ,− which imparts the desired property.…”

mentioning

confidence: 99%

Flame Retardant Behavior of Polyelectrolyte−Clay Thin Film Assemblies on Cotton Fabric

et al. 2010

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Cotton fabric was treated with flame-retardant coatings composed of branched polyethylenimine (BPEI) and sodium montmorillonite (MMT) clay, prepared via layer-by-layer (LbL) assembly. Four coating recipes were created by exposing fabric to aqueous solutions of BPEI (pH 7 or 10) and MMT (0.2 or 1 wt %). BPEI pH 10 produces the thickest films, while 1 wt % MMT gives the highest clay loading. Each coating recipe was evaluated at 5 and 20 bilayers. Thermogravimetric analysis showed that coated fabrics left as much as 13% char after heating to 500 degrees C, nearly 2 orders of magnitude more than uncoated fabric, with less than 4 wt % coming from the coating itself. These coatings also reduced afterglow time in vertical flame tests. Postburn residues of coated fabrics were examined with SEM and revealed that the weave structure and fiber shape in all coated fabrics were preserved. The BPEI pH 7/1 wt % MMT recipe was most effective. Microcombustion calorimeter testing showed that all coated fabrics reduced the total heat release and heat release capacity of the fabric. Fiber count and strength of uncoated and coated fabric are similar. These results demonstrate that LbL assembly is a relatively simple method for imparting flame-retardant behavior to cotton fabric. This work lays the foundation for using these types of thin film assemblies to make a variety of complex substrates (foam, fabrics, etc.) flame resistant.

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“…LbL coatings/films can be applied by either dip coating [26,27] or spray coating [28,29] . They have range of functionalities that can produce conducting films [30][31][32] , antireflection films [33,34] , and oxygen barriers [35,36] . The downside of LbL is each additional monolayer (ML) requires an additional deposition and washing step; therefore, 20 or more monolayer coatings required a total of 30 or more steps in the fabrication process, More recently, researchers have pivoted from layer-bylayer assembly and are aiming for single bath processes for fabricating a flame retardant coating on fabrics [37] and polyurethane foams [38] because it can be faster, use less materials, and generate less waste.…”

Section: Introductionmentioning

confidence: 99%

Aqueous-based amphiphile solutions used as gel coatings to reduce flammability of cotton fabrics

Thompson¹,

Love²,

Davis³

2019

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This study reports on the change in flammability of cotton fabrics caused by water-insoluble gel coatings applied from a single bath solution formulated with polymeric micelles and flame retardant amphiphiles. The flame resistant coatings are made from low concentration aqueous formulations of polyethylene oxide-polypropylene oxide-polyethylene oxide, and 5 % to 15 % mass fraction melamine and sodium hexametaphosphate. The coated cotton fabrics were tested and characterized by a variety of bench-scale tools, such as vertical flame testing, micro-scale combustion calorimetry, and thermogravimetric analysis. Properties such as increased ignition resistance, self-extinguishment, and higher decomposition temperatures were measured, relative to the uncoated cotton.

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Micropatterning and Impedance Characterization of an Electrically Percolating Layer‐by‐Layer Assembly

Cited by 7 publications

References 40 publications

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Polyelectrolyte/Nanosilicate Thin-Film Assemblies: Influence of pH on Growth, Mechanical Behavior, and Flammability

Flame Retardant Behavior of Polyelectrolyte−Clay Thin Film Assemblies on Cotton Fabric

Aqueous-based amphiphile solutions used as gel coatings to reduce flammability of cotton fabrics

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