Allyamine Hydrochloride Research Articles

Flexible multilayer electrode films consisted of polyaniline and polyelectrolyte by layer-by-layer self-assembly

In this research, we report the fabrication of flexible multilayer electrode films by layer-by-layer self-assembly (LBL-SA) technique. The conductive multilayer films consisted of weak cationic polyelectrolytes such as polyethylenimine (PEI)/poly(aniline) (PANi) and poly(allyamine hydrochloride) (PAH)/poly(aniline) (PANi) were fabricated on poly(ethylene terephalate) (PET) substrate coated with poly(diallyldimethylammonium chloride) (PDDA)/poly(sodium 4-styrenesulfonate) (PSS) under-layer. (PEI/PANi)20 film was covered with N,N-dimethylactamide (DMAC) to promote metallic ions and poly(vinylpyrrolidone) (PVP) layer was coated to avoid the hydrolysis of DAMC and metallic ion. The conductivity, morphology, and transmittance of electrode films were investigated by I–V characterization using the four terminal probe unit, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and UV–vis spectrometry. The (PDDA/PSS)5/(PEI/PANi)20/(DMAC-Ag/PVP-Ag) electrode film fabricated on PET substrate showed the resistance of 15kΩ and transmittance of over 70%. These experimental results showed that the conductive films with uniformity and transparence were formed on the flexible PET substrate by LBL-SA method.

Preparation of Nanoporous Polyelectrolyte Multilayer Films via Nanoparticle Templating

Polyelectrolyte−nanoparticle hybrid multilayer films were used as templates for the preparation of nanoporous polymer thin films. The hybrid multilayers were constructed by consecutively depositing an anionic blend of silica nanoparticles (SiO2 NPs) and poly(acrylic acid) (PAA) and a cationic polyelectrolyte, poly(allyamine hydrochloride) (PAH). Layer-by-layer growth of the multilayers with different SiO2 NP sizes (25, 45, and 85 nm in diameter) and at different pH was followed by quartz crystal microgravimetry (QCM). Film buildup, as assessed by QCM mass changes, was 3 times larger when assembled with PAH at pH 9 than with PAH at pH 5. After chemically cross-linking the PAA/PAH within the films, the SiO2 NPs were removed by dissolution with hydrofluoric acid. Atomic force microscopy and transmission electron microscopy were used to characterize the porous films formed and revealed that the pore size could be controlled by using SiO2 NPs of different size. The adsorption of bovine serum albumin (BSA) on the porous thin films showed that the amount of BSA adsorbed increased with increasing bilayer number, suggesting the protein infiltrated the films. This provides opportunities to tune the protein content in the films, which is of interest for applications in biocatalysis and biosensing.

The influence of void space on antireflection coatings of silica nanoparticle self-assembled films

This study investigates the deposition by ionic self-assembly of alternating silica nanoparticle and poly(allyamine hydrochloride) layers with the goal to create a single-material antireflection coating. The condition that the optical thickness of the film be equal to λ∕4 can be satisfied by depositing the requisite number of bilayers to obtain minimum reflectivity at the chosen wavelength. The second condition for antireflection, that the index of refraction of the film be equal to nc=n1n2, where n1 and n2 are the refractive indices of the media on each side of the film, requires that nc=1.22 for a film with air on one surface and glass (assuming n=1.50) on the other. Such a low index of refraction can be created in films consisting of nanoparticles if the proper volume fraction of void space exists in the film. In the wavelength range λ=350–700nm, minimum reflectivities of ⩾2.0%, ⩽0.2%, and ⩽0.2% were obtained with films created on both sides of a glass slide using 15, 45, and 85nm average diameter silica nanoparticles, respectively. The maximum transmittances for the corresponding films were 97%, ⩾98%, and ⩾97%. The minimum reflectance of films prepared with 15nm average diameter silica nanoparticles was limited by insufficient void volume in the films. The maximum transmittances of films prepared with 45 and 85nm average diameter silica nanoparticles were limited by diffuse scattering arising from the inhomogeneous morphology of the films. The extinction of normal incident light (=1−R−T, where R and T are the reflectance and transmittance, respectively) provides a measure of diffuse scattering for light with wavelength longer than the absorption edge of the film. It was found that the extinction is proportional to 1∕λ4 for λ>450nm suggesting that the mechanism for extinction at long wavelengths is Rayleigh scattering. The Rayleigh slope (diffuse scattering intensity versus 1∕λ4) increased with increasing diameter silica nanoparticles. For a given average diameter silica nanoparticle, the Rayleigh slope increased with increasing film thickness for films less than approximately 150nm thick, but did not depend on film thickness, within experimental scatter, for films that were thicker than 150nm. The results suggest that the source of Rayleigh scattering was not in the bulk of the film (such as, fluctuations in the index of refraction), but rather was primarily associated with surface roughness.

Consecutively spin-assembled layered nanoarchitectures of poly(sodium 4-styrene sulfonate) and poly(allylamine hydrochloride)

The recently established spin-coating electrostatic self-assembly (SCESA) technique has been shown to facilitate not only the rapid fabrication of polyelectrolyte multilayer assemblies, but also allow each layer to be easily controlled on a monomolecular scale by minimizing the film thickness across a substrate surface. In this paper, the influence of polyelectrolyte concentration on the amount and thickness of spin-deposited polymer films has been examined for a multilayer system of poly(allyamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS), when the washing steps employed for removing weakly bound polyelectrolytes on a resultant film on a substrate are excluded from the standard fabrication procedure of the SCESA method. The thickness of the spin-deposited PAH/PSS bilayer increased linearly for the PSS concentrations in the range from 1 to 10 mM with PAH constant at 1 mM, which demonstrates the uniform deposition of each layer material onto the thin film. The thickness of PAH/PSS bilayers increased from 1.43 ± 0.06 to 3.37 ± 0.08 nm as the PSS concentration increased from 1 to 10 mM, while the PAH concentration was kept constant at 1 mM. The multilayer films were found to be stable in a good solvent (H 2O) for at least 30 h, without any noticeable loss of the adsorbed layer component of the polyelectrolyte. This improvement to the SCESA method (exclusion of washing steps) provides a convenient way to create multilayer heterostructures with the thickness of each layer being easily adjusted.