Linear analogs characterization

Hyperbranched poly(ethyl methacrylate)s prepared by the photo-initiated radical polymerization of the inimer 13 were characterized by GPC with a lightscattering detector [51]. The hydrodynamic volume and radius of gyration (i g) of the resulting hyperbranched polymers were determined by DLS and SAXS, respectively. The ratios of Rg/R are in the range of 0.75-0.84, which are comparable to the value of hard spheres (0.775) and significantly lower than that of the linear unperturbed polymer coils (1.25-1.37). The compact nature of the hyperbranched poly(ethyl methacrylate)s is demonstrated by solution properties which are different from those of the linear analogs. 

The characterization of branched or cyclic structures by the g- and h-factors has the disadvantage that the properties of the analogous linear chains must be known. Such characterization requires a great deal of work in preparative chemistry as well as accurate physical chemical measurements, and in some cases the linear analogs are not even known. In such cases, a direct combination of the mean-square radius of gyration and the hydrodynamic radius leads to the very useful dimensionless parameter188. ... 

Preparation and characterization of highly branched aromatic polymers, polyphenylenes, polyesters, polyethers, and polyamides, were reviewed. These polymers were prepared from condensation of AB -type monomers, which gave noncrosslinked, highly branched polymers. The polymer properties are vastly different compared to their linear analogs due to their resistance to chain entanglement and crystallization. 

Thus, the fractal analysis methods were used above for treatment of comb-like poly(sodiumoxi) methylsylseskvioxanes behavior in solution. It has been shown that the intrinsic viscosity reduction at transition from a linear analog to a branched one is due to the sole factor, namely, to a macromolecule connectivity degree enhancement, characterized by spectral dimension. This conclusion is confirmed by a good correspondence of the experimental and calculated according to Mark-Kuhn-Houwink equation fiactal variant intrinsic viscosity values. It has been shown that qualitative transition of the stmcture of branched polymer macromolecular coil from a good solvent to 0-solvent can be reached by a solvent change. 

Characterization of 9 and other linear analogs was performed using a variety of spectroscopic and chromatogri hic techniques. As expected the materials were essentially monodisperse and showed only a single molecular ion by MALDI-TOF at the desired molecular weight. However the and NMR spectra for the linear... 

In a following work, the authors characterized the materials in more detail. They found a smaller hydrodynamic volume compared to the linear analogs and depicted the different linear, dendritic, semidendritic, and terminal units by NMR spectroscopy. 

Synthetic analog clusters have played a pivotal role in development of Fe-S cluster biochemistry. Indeed, the synthesis and characterization of clusters with [Fe2( t2-S)2], [Fe4( (,3-S)4], and linear [Fe3( t2-S)4l cores by Holm and co-workers (47, 48) were crucial in establishing the properties of these clusters and identifying these types of centers in biological systems. However, the synthesis of a cluster with the physi-... 

As auranofin demonstrates both anti-arthritic and antitumor effects, many analogs differing in the thiolate and the phosphine residues have been characterized [18, 21, 51-53]. Like auranofin, these complexes are generally linear at the two-coordinate gold center. Di- i-(diethylphosphinoethylthio)digold(I) is a complex that... 

This effect, which is in a loose sense the nonlinear analog of linear optical rotation, is based on using linearly polarized fundamental light and measuring the direction of the major axis of the ellipse that describes the state of polarization of the second-harmonic light. For a simple description of the effect, we assume that the expansion coefficients are real, as would be the case for nonresonant excitation within the electric dipole approximation.22 In this case, the second-harmonic light will also be linearly polarized in a direction characterized by the angle... 

---