Laser-Induced Light Absorption in 2D Silver Nanoparticle Array

Nanocomposite comprising planar array of silver nanoparticles in polymer matrix was submitted to Ar laser irradiation at the wavelength of 488 nm. The extinction spectra of the array were measured as a function of the irradiation power density. Two collective surface plasmon modes, namely T and P, associated with particle dipoles parallel and perpendicular to the plane of the layer were identified. The extinction bands of T and P modes exhibit blue spectral shift with the increase of radiation power. P mode band broadens when laser power increases. The observed effects are explained by heating of the nanocomposite by the intense laser radiation

Optical Properties of Multilayered Metal–Dielectric Structures Containing Silver Nanoparticles

In this paper we report on fabrication and optical properties of metal-dielectric nanostructures consisting of stacked monolayers of silver nanoparticles. The extinction spectra of the nanostructures were studied as a function of the angle of incidence and polarization state of the incident light. Two collective surface plasmon modes, namely T and P, associated with particle dipoles parallel and perpendicular to plane of the layer were identified for a single monolayer of the particles. The extinction bands of T and P modes exhibit different intensity and frequency dependences on the angle of incidence. More pronounced angular dependences for P mode band indicate the stronger coupling of dipoles for P mode than for Tone. A new N mode was observed for the structures comprising three nanoparticle layers. This new mode originated from surface plasmon coupling between adjacent layers

Optical Properties of Multilayered Metal–Dielectric Structures Containing Silver Nanoparticles

In this paper we report on fabrication and optical properties of metal-dielectric nanostructures consisting of stacked monolayers of silver nanoparticles. The extinction spectra of the nanostructures were studied as a function of the angle of incidence and polarization state of the incident light. Two collective surface plasmon modes, namely T and P, associated with particle dipoles parallel and perpendicular to plane of the layer were identified for a single monolayer of the particles. The extinction bands of T and P modes exhibit different intensity and frequency dependences on the angle of incidence. More pronounced angular dependences for P mode band indicate the stronger coupling of dipoles for P mode than for Tone. A new N mode was observed for the structures comprising three nanoparticle layers. This new mode originated from surface plasmon coupling between adjacent layers

The synthesis, characterization and targeting ability of nano-scale enrichment polymer layers

Thin polymer films have been utilized as enrichment layers for evanescent waveguide chemical sensors and other analytical techniques. This is due to the fact that the chemical nature of polymers is ideal for trapping chemically similar organic molecules making analysis more convenient. Specifically, research in this area of volatile organic compounds (VOCs) detection, focused has been given to identifying a single polymer film of micron scale thickness to target one analyte. This work focuses on the design and use of multiple polymers in one enrichment layer to target VOCs to facilitate detection. Two distinct layered enrichment systems were synthesized via the “grafting to” approach. The end application is to apply these polymers onto mid-infrared transparent evanescent wave micro-disk or micro-ring resonators. Analysis of the polymer affinity to VOCs and to act as enrichment layers is determined by the thickness increase caused by swelling of the film when exposed to the analyte vapor. Detection analysis was done using attenuated total reflection (ATR) FT-IR spectroscopy. The polymer layered systems were characterized by atomic force microscopy, ellipsometry and infrared spectroscopy. Studies of pure analyte vapors and mixtures were conducted in saturated conditions

Switching Transport through Nanopores with pH-Responsive Polymer Brushes for Controlled Ion Permeability

Several nanoporous platforms were functionalized with pH-responsive poly(methacrylic acid) (PMAA) brushes using surface-initiated atom transfer radical polymerization (SI-ATRP). The growth of the PMAA brush and its pH-responsive behavior from the nanoporous platforms were confirmed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The swelling behavior of the pH-responsive PMAA brushes grafted only from the nanopore walls was investigated by AFM in aqueous liquid environment with pH values of 4 and 8. AFM images displayed open nanopores at pH 4 and closed ones at pH 8, which rationalizes their use as gating platforms. Ion conductivity across the nanopores was investigated with current–voltage measurements at various pH values. Enhanced higher resistance across the nanopores was observed in a neutral polymer brush state (lower pH values) and lower resistance when the brush was charged (higher pH values). By adding a fluorescent dye in an environment of pH 4 or pH 8 at one side of the PMAA-brush functionalized nanopore array chips, diffusion across the nanopores was followed. These experiments displayed faster diffusion rates of the fluorescent molecules at pH 4 (PMAA neutral state, open pores) and slower diffusion at pH 8 (PMAA charged state, closed pores) showing the potential of this technology toward nanoscale valve applications

Modification of the Surface of a Substrate by Adsorbed Polymer Interlayers for the Control of Adhesion

A good correlation between the parameters of an adsorbed polymer interlayer and the strength of an adhesive joint was observed. Such polymer interlayers were obtained beforehand by the adsorption of polyacrylates, polymethacrylates and their copolymers with acrylic and methacrylic acid from solution on to the surface of aluminium plates. Oligocarbomethacrylate was used as an adhesive. Contact angle measurements were employed for investigating the structure of the adsorbed polymer layers. It was found out that the fraction of sites screened by the polymer, the fraction of the substrate available for the adhesive and the fraction of attached segments affects the adhesion strength

Dependence of phase morphology and mechanical properties of PS/SBR/PE ternary blends on composition: transition from core-shell to triple-phase continuity structures

The weight ratio of PE and PS in ternary PS/SBR/PE blends has been changed at constant SBR content (25 wt%). When the matrix is either PE or PS, the dispersed phase has a core-shell structure with SBR forming the shell. The size of the core expectedly increases with the content of the core-forming polymer. In some composition range, the three phases are simultaneously continuous, SBR being localized in between the co-continuous PE and PS phases. The ultimate mechanical properties of the ternary blends containing SBR/PE and SBR/PS core-shell dispersed phases are close to the properties of the PS/SBR and PE/SBR binary blends, respectively. Some synergism in the elongation at break of the ternary blends is observed when core-shell SBR/PS phases are dispersed in PE matrix