Hydrodynamic size of polymers

The major advantage of the capillary hydrodynamic chromatography is that the mobile phase does not need to have similar solubility parameter as the sample and packing material. (In SEC, nonsize exclusion effects may be observed if the solubility parameter of the sample, packing material, or mobile phase is considerably different.) Therefore, the hydrodynamic size of polymers can be studied in a 0 solvent and even in a solvent that is not compatible with any currently available SEC packing material (9). Figure 22.4 is an example of polystyrene separation in both THF and diethyl malonate. Diethyl malonate is the 0 solvent of polystyrene at 31-36 C. 

Similarly, the hydrodynamic size of polymer coils, expressed as the radius of gyration under the critical conditions, also depends on the eluent nature [67]. Thus, the critical conditions can not be related to a specific molecular conformation of PS and the hydrodynamic dimensions of macromolecules with the same molar mass are different in various mixed mobile phases corresponding to CEEC. 

To measure the flow time of a solution, the Ubbelohde-type capillary viscometer is used. The flow time of solution is compared with the flow time of base fluid (water). As an example. Figure 13.10 shows the relative viscosity for the PEO/SDS system. When surfactant is added to polymer solution, the hydrodynamic size of polymer is increased due to the attachment surfactant micelles to the backbone of PEO chains. This causes an increase in relative viscosity. The relative viscosity begins to rise at CAC as shown in Eigure 13.10.When the surfactant concentration reaches PSP, the relative viscosity begins to flatten. 

The length of monomer unit of MA is taken to be 0.25 nm [71]. The length of the polymer chain equal to the turn or the diameter of the protein globule is calculated taking into account the hydrodynamic size of the protein molecule via Stockes radius (Rsl). 

The results are discussed in terms of collision rate theories where the shear rate in the system and the hydrodynamic sizes of the particles and the polymer molecules are considered. 

Under a variety of conditions, plasmid DNA undergoes a dramatic compaction in the presence of condensing agents such as multivalent cations and cationic polymers. Naked DNA coils, typically with a hydrodynamic size of hundreds of nanometers, after condensation it may become only tens of nanometer in size. Contrary to proteins which show a unique tertiary structure, DNA coils do not condense into unique compact structure. Cationic polymers execute their gene carrier function by their condensation effect on gene materials and, furthermore, their protection effect on DNA from nuclease digestion. Currently, the most widely used cationic polymers in research include linear or branched PEI (poly (ethyleneimine) (161-165), polypeptides such as PLL (poly-L-lysine) (166-169), PLA (poly-L-arginine) (170). 

Figure 8 illustrates the relationship between inherent viscosity (IV) and concentration for PBI/PAr/NMP solutions. It is interesting to note that the IV of all solution blends exhibited normal polymer solution characteristics. At a fixed concentration (0.5%), it was noted that the IV of the solution blends exceeded the rule of mixtures (see Fig. 9) suggesting that PBI and PAr exhibit specific interactions in a dilute solution, such that the resulting hydrodynamic sizes of the blends were greater than that of the calculated averages based on each component. 

Structure of each nonlinear polymer molecule can be estimated, most simply in a 0 solvent, using the structural information shown in Fig. 19. By determining the hydrodynamic size of each polymer molecule, we can also estimate the size exclusion chromatography (SEC) elution curve [302-306]. 

The first pathway is the formation of mixed micelles or hemimicelles, composed of polymer-bound hydrophobes comicellized with surfactant molecules. Intermolecular physical cross-links often enhance the viscosity of the micellar solutions. The second pathway is intramolecular comicellization so that the hydrodynamic size of the associates contracts. 

In summary, we have reported a new strategy to minimize the hydrodynamic size of QDs by using multifunctional, multidentate polymer ligands. A novel finding is that a balanced composition of thiol and amine groups yields... 

The block of data concerned with this area generally does not consider the developments concerning the solution behavior of nonmobility control polymers which has been reported in the polymer literature. Implicitly, one is led to believe that the mobility control polymer solutions are unique and have little in common with more conventional polymer solutions. This study will show that there is a direct qualitative correlation between the behavior of mobility control polymer solutions and other solutions of macromolecules. In particular, it is demonstrated that the viscous properties are directly related to the hydrodynamic size of the polymer chain and the influence of system characteristics such as salt concentration, shear rate, etc., can be correlated with the effective size of the polymer molecule in solution. Consequently, this study suggests that more emphasis should be placed on the measurement of the molecular size of mobility control polymers in solution if a fundamental understanding of these solutions is to be developed. 

The dominate factor which controls the solution properties of mobility control polymers is the configuration (and hence size) that the molecule assumes in a given environment. Although the viscosity of a polymer solution is related to the hydrodynamic size of the polymer molecules, it is difficult to determine the unique relationship between viscosity and size. However, exten-... 

Rudin and Hoegy [43] have considered the assumption, inherent in the universal calibration procedure, that the hydrodynamic volume of a polymer at the concentration range adopted in SEC analysis is that which pertains at infinite dilution, and discuss whether this can account for apparent failures in some instances. A model is presented to estimate hydrodynamic volumes of polymers at finite concentrations and provide a universal calibration. Polypropylene is one of the examples used to illustrate the size of the effect. 

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