Polydispersity chemical

H. F. Yang, C. S. Shan, F.H. Li, D.X. Han, Q. X. Zhang, L. Niu, Covalent functionalization of polydisperse chemically-converted graphene sheets with amine-terminated ionic liquid, Chemical Communications, vol. 26, pp. 3880-3882, 2009. 

Figure 4.20 Illustration of the preparation of polydisperse chemically converted graphene (p-CCG) from graphite oxide (GO) by amine-terminated IL [67], Reproduced by permission of The Royal Society of Chemistry.

Physical and Chemical Properties of Lignosulfonates. Even unmodified lignosulfonates have complex chemical and physical properties. Their molecular polydispersiti.es and stmctures are heterogeneous. They are soluble ia water at any pH but iasoluble ia most common organic solvents. 

Several colloidal systems, that are of practical importance, contain spherically symmetric particles the size of which changes continuously. Polydisperse fluid mixtures can be described by a continuous probability density of one or more particle attributes, such as particle size. Thus, they may be viewed as containing an infinite number of components. It has been several decades since the introduction of polydispersity as a model for molecular mixtures [73], but only recently has it received widespread attention [74-82]. Initially, work was concentrated on nearly monodisperse mixtures and the polydispersity was accounted for by the construction of perturbation expansions with a pure, monodispersive, component as the reference fluid [77,80]. Subsequently, Kofke and Glandt [79] have obtained the equation of state using a theory based on the distinction of particular species in a polydispersive mixture, not by their intermolecular potentials but by a specific form of the distribution of their chemical potentials. Quite recently, Lado [81,82] has generalized the usual OZ equation to the case of a polydispersive mixture. Recently, the latter theory has been also extended to the case of polydisperse quenched-annealed mixtures [83,84]. As this approach has not been reviewed previously, we shall consider it in some detail. 

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

To run the residence time distribution experiments under conditions which would simulate the conditions occurring during chemical reaction, solutions of 15 weight percent and 30 percent polystyrene in benzene as well as pure benzene were used as the fluid medium. The polystyrene used in the RTD experiment was prepared in a batch reactor and had a number average degree of polymerization of 320 and a polydispersity index, DI, of 1.17. 

SteU, G Rikvold, PA, Polydispersity in Elnids, Dispersion, and Composites Some Theoretical Results, Chemical Engineering Commnnications 51, 233, 1987. 

Figure 6. TEM micrographs representing the transformations of (a) polydispersed nanoparticles upon (b) alkanethiol addition at room temperature and (c) after digestive ripening (inverse micelle system). (Reprinted with permission from Ref [49], 2002 American Chemical Society.)...

A theoretical prediction of water-soluble polymer solutions is difficult to obtain due to their ability to build up aggregations and associations. A prediction of the viscosity yield is much easier to observe for solutions of synthetic polystyrene due to its simple solution structure. These solutions have been well characterized in other studies [19-23] concerning their chemical composition, molar mass and sample polydispersity. 

There are various ways to check the quality of the resulting structures with respect to experiment. A typical check would be to compare the mean square end-to-end distance with results from scattering experiments. However, since the experimental samples are highly polydisperse, the results from scattering experiments are somewhat questionable [195]. Furthermore, a crucial check is the direct comparison of conformations of systems. In order to be able to compare the conformations resulting from simulations unanimously to experiment we reintroduce the chemical details into the coarse-grained chain. This is one of the reasons why it is so important to device a mapping procedure which stays close to the chemical structure of the objects. We have a one-... 

For some polymers, like polystyrene or poly(methyl methacrylate), narrow standards of known molar mass and small polydispersity are commercially available, which can be used for calibration. Unfortunately, such standards are not available for all polymers and then the obtained true molar masses of a specific polymer might differ by a factor of two from the value obtained by calibration with, e.g., polystyrene [30] (see Section 9.1). This problem can be resolved by the so-called universal calibration, which is based on the finding that the retention volume of a polymer is a single-valued function of the hydrodynamic volume of the polymer, irrespective of its chemical nature and... 

Weight average molecular weights of poly(HAMCL) with saturated or unsaturated pendent groups are relatively low, compared to Mw s of poly(HASCL), and in the range of 60,000 to 360,000 g mol as depicted in Table 2 [4,30,35,36]. Also for the poly(HAMCL) copolymers, the molecular weight distributions are unimodal. Their polydispersities are in the range of 1.6-2.4, which is narrower than the polydispersity of poly(3HB-co-3HV) copolymers, and close to the theoretical value of 2.0 for synthetic polycondensates such as chemically synthesized polyesters [54]. 

Matveev V.V. Calculation of the Electrochemical Characteristics of Porous Electrodes with a Polydisperse Crystal Structure (Rus.), Problems of Chemistry and Chemical Technology IVoprosy Khimii i Khimicheskoy Tekhnologiil (Ukrainian Journal). 2001 3 96-111. 

Characteristic initiation behavior of rare earth metals was also found in the polymerization of polar and nonpolar monomers. In spite of the accelarated development of living isotactic [15] and syndiotactic [16] polymerizations of methyl methacrylate (MMA), the lowest polydispersity indices obtained remain in the region of Mw/Mn = 1.08 for an Mn of only 21 200. Thus, the synthesis of high molecular weight polymers (Mn > 100 x 103) with Mw/Mn < 1.05 is still an important target in both polar and nonpolar polymer chemistry. Undoubtedly, the availability of compositionally pure materials is a must for the accurate physical and chemical characterization of polymeric materials. 

The above phenomenon is due to the pronounced polydispersity of these products in their chemical size l described by the Flory exponential distribution. Because the composition of each macromolecule of the sample under investigation is unambiguously related to its degree of polymerization l, the Flory distribution for l in a polymer sample is responsible for its significant composition inhomogeneity. 

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