Forward recoil spectroscopy, polymer

Measurement of transient concentration profiles of deuterated polymers in polymer blends using forward recoil spectroscopy Measurement of transient concentration profiles of fluorescently labeled molecules in capillary tubes using epifluorescence microscopy Measurement of transient concentration profiles of fluorescently labeled molecules in biological tissues using epifluorescence microscopy Fluorescence recovery (or redistribution) after photobleaching (FPR)... 

Tao, et al. [93] measured Dg (using PFGNMR and forward recoil spectroscopy) and t) of hydrogenated polybutadienes in alkanes. Polymer volume fractions extended from 0.2 up to the melt while M extended from 4.8 to 440kDa with < 1.03. Tao,... 

Tead and Kramer [122] studied diffusion of 255 kDa deuterated polystyrene through solutions of large-molecular-weight (93, 255, and 20 000 kDa) polystyrenes, with a low-M (10 kDa) polystyrene melt ts the solvent. The matrix polymer volume fraction covered 0 < < 1. Dp was obtained using forward recoil spectroscopy to measure the time-... 

The characterization of surface structure for miscible blends is a more formidable task, requiring techniques that are sensitive to the composition of the blend within several nanometers of the surface. X-ray photoelectron spectroscopy (xps) provided the first direct and quantitative evaluation of surface composition and surface composition gradients for miscible polymer blends of poly(vinyl methyl ether) (PVME) and polystyrene (PS) (22,23). Since that time, the situation has changed dramatically with the advance of theory and the application of exciting new experimental techniques to this problem. In addition to xps and pendant drop tensiometry (22,23), forward recoil spectroscopy (28), neutron (29) and x-ray reflectivity (30), secondary ion mass spectroscopy (either dynamic or time-of-flight-static) (31,32), and attenuated total reflectance Fourier transform infrared spectroscopy (33-35), have been applied successfully to study surface segregation. The advent of these new tools has enabled a multitechnique experimental approach toward careful examination of the validity of current surface segregation theories (36-39). 

Tao, et al. used forward recoil spectroscopy and PFGNMR to determine Ds of hydrogenated polybutadienes in alkane solvents(15). Measurements of the dynamic shear moduli were used to determine the low-shear viscosity of the same solutions. Tao, et al. s measurements of Ds appear in Figure 8.7, together with fits of Ds to scaUng-law and stretched-exponential dependences on polymer concentration and molecular weight. The root-mean-square fractional errors in the displayed fits to the scaling-law and stretched-exponential forms are both 20%. For the... 

The main experimental techniques used to study the failure processes at the scale of a chain have involved the use of deuterated polymers, particularly copolymers, at the interface and the measurement of the amounts of the deuterated copolymers at each of the fracture surfaces. The presence and quantity of the deuterated copolymer has typically been measured using forward recoil ion scattering (FRES) or secondary ion mass spectroscopy (SIMS). The technique was originally used in a study of the effects of placing polystyrene-polymethyl methacrylate (PS-PMMA) block copolymers of total molecular weight of 200,000 Da at an interface between polyphenylene ether (PPE or PPO) and PMMA copolymers [1]. The PS block is miscible in the PPE. The use of copolymers where just the PS block was deuterated and copolymers where just the PMMA block was deuterated showed that, when the interface was fractured, the copolymer molecules all broke close to their junction points The basic idea of this technique is shown in Fig, I. 

---