Using a generalized multiparticle Mie theory, we calculated the optical properties of gold nanoparticle (Au NP) pairs of 8−80 nm in diameter (D) and 0.1−120 nm in interparticle gap (s) under typical experimental conditions: an unpolarized incident light and random orientation of the pairs in space. By analyzing the extinction spectra of coupled spheres, three ranges of interparticle separations (long, middle and short) with different plasmon coupling regimes were distinguished. For long interparticle distances, a single plasmon peak in the spectrum at wavelength λ p red-shifts exponentially relative to that of an isolated particle at wavelength λ 0 as a function of x = s/D: Δλ/λ 0 = (λ p − λ 0 )/ λ 0 = a exp(−x/t), with a decay constant (t = 0.19) being nearly independent of nanoparticle diameters at D < 50 nm. Stronger shifts (0.04 < a < 0.08) are observed for 30−60 nm Au NPs. In the middle distance range (0.02 < s/D < (s/ D) split ), the extinction spectra of dimers have two plasmon peaks: transverse and longitudinal. The shift of long-wavelength peak can be reasonably approximated by the equation Δλ/λ 0 = a 0 + a 1 exp(−x/t 1 ), where the parameters a 1 (= 0.352) and t 1 (= 0.032) do not depend on the nanoparticle sizes, and a 0 increases with particle size. The boundary between the long and middle interparticle distance ranges, (s/D) split , strongly varies with the Au NP diameter. At s/D < 0.02, the birth and evolution of third plasmon peak that is located between the transverse and longitudinal peaks has a strong effect upon the spectral properties of closely coupled NPs. Now the fractional shift of the longitudinal peak obeys the equation Δλ/λ 0 = a 0 + a 1 exp(−x/t 1 ) + a 2 exp(−x/t 2 ), where t 2 = 0.004 and a 2 = 0.643. The constancy of coefficients a i and t i for Au NPs of different sizes means that the fractional shifts of plasmon resonances of coupled pairs corrected by parameter a 0 have to fall on a common curve. The obtained results clearly point that the Au NPs pairs can be used as the highly sensitive instruments to measure both absolute distances and their changes in the nanometric range of lengths.

Tensile drawing of the poly(ethylene terephthalate) (PET) samples in semidilute solutions of poly(ethylene oxide) (PEO) with the molecular mass ranging from 4 × 104 to 1 × 106 proceeds via the mechanism of solvent crazing. This process is accompanied by the penetration of PEO into the porous structure of crazes, and this conclusion is proved by the data on the composition of the resultant blends as well as by the direct electron microscopic observations. Effective diameter of pores in the nanoporous structure of the solvent-crazed PET samples is estimated by the method of pressure-driven liquid permeability. Structure of PEOs is studied by the methods of dynamic light scattering and capillary viscometry as a function of the molecular mass and polymer concentration in the solutions. Penetration of PEO into the solvent-crazed nanoporous structure proceeds under so-called “confined” conditions when the hydrodynamic radius of a polymer coil is comparable or higher than the effective dimensions of pores in the crazes. Penetration of the PEO macromolecules into the porous structure of the solvent-crazed PET-based sample via diffusion under the action of the concentration gradient is compared with the flow-assisted penetration in the course of the tensile drawing of the PET samples in the PEO solutions. Content of PEO in the pores of the solvent-crazed polymer samples is higher than that in the surrounding solution, and this fact can be explained by the adsorption of PEO on the highly developed surface of the fibrillated polymer in crazes. Penetration of PEO into the porous structure upon tensile drawing proceeds much quicker (minutes) as compared with the attainment of the equilibrium content of the polymer under the action of the concentration gradient (days).

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