Polymerized Allylamine Films Research Articles

Surface stress control using ultraviolet light irradiation of plasma-polymerized thin films

We investigated the surface stress change of plasma-polymerized allylamine films on 2μm thick silicon micromechanical cantilever substrates induced by ultraviolet light (UV) irradiation. Compressive surface stress was generated during the UV irradiation of the plasma-polymerized films in a dry environment, whereas tensile stress was measured in a humid environment. Fourier transform infrared spectroscopic analysis indicated two mechanisms taking place depending on the environmental conditions. These were attributed to crosslinking and oxidation reactions of the plasma polymer. UV irradiation of plasma polymerized allylamine films at defined humidity suggests a feasible method for achieving tensile and compressive surface stress patterning.

STW gas sensors using plasma-polymerized allylamine

Gas sensors generally consist of two major components: a gas recognition element which provides the specificity and selectivity of the measurement and a physical transducer which translates the gas absorption or desorption event into electronic signal. In this paper, plasma polymerized allylamine (PPAa) film is used as a gas recognition element and a surface transverse wave (STW) device is used as a physical transducer. It is confirmed that STW sensor devices coated with PPAa films provide high sensitivity for moisture. The STW sensor device with a 63 nm PPAa film provided twenty four times higher sensitivity than that of a non-coated STW device. In addition, the chemical structure of PPAa films is characterized by the FT-IR and the contact angle measurement.

Microstructural evolution of allylamine polymerized plasma films

The present paper deals with the characterization of plasma polymerized allylamine films. The films were characterized using a large panel of techniques such as Fourier transformation infrared spectroscopy, X-ray photoemission spectroscopy and ellipsometry. The film microstructure was investigated as a function of the deposition power while other process parameters (gas mixture flow, pressure) were kept constant. The microstructure shows a strong dependence on the deposition power. A power transition has been identified outlining two deposition modes in agreement with a growth model developed for carbon nitride thin films. Conditions of deposition closed to this transition provide a film microstructure interesting for absorption and adhesion of biomolecules i.e. high NH 2 content, high porosity and high deposition rate.

Distributions of Functional Groups in Plasma Polymerized Allylamine Films by Scanning Force Microscopy Using Functionalized Probe Tips

Thin films of poly(allylamine) on silicon were prepared by polymerization of allylamine in a pulsed glow-discharge plasma reactor. The films were characterized by surface plasmon spectroscopy (SPS) and waveguide mode spectroscopy (WaMS), as well as by X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. It was shown that by variation of the duty cycle the film thickness as well as the content of amino and nitrile groups could be controlled. Scanning force microscopy (SFM) measurements with chemically functionalized tips led to a qualitative correlation of adhesion forces with the content of amino groups. Laterally resolved adhesion force measurements indicated the presence of a heterogeneous local environment of the amino groups, with patches exhibiting differences in hydrophobicity on a sub-50-nm scale.

Thin Film Plasma Deposition of Allylamine; Effects of Solvent Treatment

AbstractAmine-functionalized thin films were prepared by plasma induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed plasma conditions to control the film chemistry, all other process variables being held constant. Using plasma polymerized films for subsequent grafting reactions or for direct biomedical applications usually involves exposure of the films to a solvent environment. It was the major focus of this work to investigate both the chemical and physical effects of solvents on plasma polymerized allylamine films. Film properties were determined using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Waveguide Mode Spectroscopy (WaMS) and Surface Plasmon Spectroscopy (SPS). WaMS provided an ideal opportunity to study the complex swelling and drying behaviour of these films by allowing a simultaneous study of the changes in film thickness and refractive index. Although the amine groups of the monomer were increasingly retained in the films as the RF duty cycle was lowered, a larger amount of oxygen was also found to be incorporated upon exposure to air. Extraction in ethanol led to a decrease in film thickness, especially for the films produced at low duty cycles, but appeared to have little effect on the film composition, as measured by XPS and FTIR.