Molar mass macromolecule

In a diagram where the reduced osmotic modulus is plotted as a function of the parameter X, a universal curve is found for linear flexible chain molecules independent of the molar mass. Macromolecules of different architecture, for instance star-like, random branched or stiff macromolecules, deviate from this curve in a characteristic way. Figure 5.6 displays this for PMAC dissolved in benzene [15]. 

FIGURE 15 Schematic representation of etfect of sample concentration on the corresponding retention volume in SEC. M is polymer molar mass, is low molar mass, macromolecules are eluted not far from Mjmolar mass, macromolecules are eluted near V. For detailed explanation, see the text... 

Disadvantages of column banks are that price, pressure, analysis time, and eluent consumption inaease. An inCTeased pressure might result in the need to reduce the flow rate and/ or to increase the temperature to have better chromatographic conditions, especially for high molar mass macromolecules. In addition, there is the potential danger of porosity mismatch for all column types, linear/mixed bed or single porosity alike. 

P. T. Callaghan andD. N. Finder. Self-diffusion ofrandom-coil polystyrene determined by pulsed field gradient nuclear magnetic resonance Dependence on concentration and molar mass. Macromolecules, 14 (1981), 1334-1340. 

The wide variety of ketomethylene and amino ketone monomers that could be synthesized, and the abiUty of the quinoline-forming reaction to generate high molar mass polymers under relatively mild conditions, allow the synthesis of a series of polyquinolines with a wide stmctural variety. Thus polyquinolines with a range of chain stiffness from a semirigid chain to rod-like macromolecules have been synthesized. Polyquinolines are most often prepared by solution polymerization of bis(i9-amino aryl ketone) and bis (ketomethylene) monomers, where R = H or C H, in y -cresol with di-y -cresyl phosphate at 135—140°C for a period of 24—48 h (92). 

Similar considerations apply to best volume flow rates for samples of different molar mass. For high molar mass samples, flow rates should be reduced to avoid shearing the macromolecule in the column. Moreover, a reduced flow rate is necessary because the diffusion coefficients of large molecules will get pretty small. This means that the macromolecule will pass by a pore in the packing material without having the time to enter it, if the linear flow rate is too high. 

Figure 5.18 Variation of intrinsic viscosity as function of molar mass for linear, hyper-branched, and dendritic macromolecules.

The sedimentation coefficient s°, or its normalized form 5 0 w function of the conformation and flexibility of a macromolecule (via its translational frictional property) and its mass. So if we are going to obtain conformation and flexibility information we need to know the molecular weight (molar mass)... 

In nature, there are 20 amino acids available for incorporation into the protein chain. They are arranged in a specific and characteristic sequence along the molecule. This sequence is generally referred to as the primary structure of the protein. Also part of the primary structure is the relative molar mass of the macromolecule. 

In order to understand polymer solution behaviour, the samples have to be characterised with respect to their molecular configuration, their molar mass and polydispersity, the polymer concentration and the shear rate. Classical techniques of polymer characterisation (light scattering, viscometry, ultracentrifugation, etc.) yield information on the solution structure and conformation of single macromolecules, as well as on the thermodynamic interactions with the solvent. In technical concentrations the behaviour of the dissolved polymer is more complicated because additional intramolecular and intermolecular interactions between polymer segments appear. 

As has been pointed out, both entropic and enthalpic interactions affect the chromatographic behavior of macromolecules. They are adjusted to the required type of separation by selecting appropriate stationary and mobile phases. In a third mode of liquid chromatography of polymers, liquid chromatography at the critical condition (LCCC) (Entelis etal., 1985,1986 Pasch, 1997), the adsorptive interactions are fully compensated by entropic interactions. This mode is also referred to as liquid chromatography at the critical point of adsorption. Hence, TAS is equal to AH and therefore, AG becomes zero. K is 1 irrespective of molar mass and, consequently, homopolymer molecules of different molar masses coelute in one chromatographic... 

In their first step towards building dendritic rotaxanes Stoddart et al. [140] reported the construction of such materials via a so-called slipping method (Fig. 24). Thus, treatment of bisparaphenylene-34-crown-10 (BPP34C10) with tris(bipyridinium) compound 54 at 50 °C in acetonitrile for 10 days afforded mono-, di-, and tris-rotaxanes 55, 56, and 57, respectively. ES-MS was used to determine the molar masses of these macromolecules while upfield shifts in the... 

Viscosity and molar mass measurements for 70 and 71 supplemented with broad H-NMR signals which depended on concentration, temperature, and solvent but independent of NMR frequency, strongly suggested self-association of these macromolecules (in a CHC13 solution). 

In order to estimate whether the true molar masses of the dendronized polymers are larger or smaller than the GPC molar masses reported in Table 1, it is useful to recall that the separation in a GPC experiment is based on the hydro-dynamic volume (Vn) of macromolecules. For flexible coils, Vn depends on the chain length (i. e. contour length) L = MxbxMo1 according to... 

In contrast to biological macromolecules such as proteins, synthetic polymers are, in general, polydisperse. Their molar masses, which show a broad distribution of... 

The term "degradation of macromolecules" concerns the processes that are accompanied by deterioration in polymer properties. Chemical processes related to the worsening polymer properties may lead to both a reduction of average molar mass due to the scission of bonds in the macromolecular chain, or to an increase of the molar mass due to the crosslinking causing the polymer to become insoluble. 

It is well-known that the coil density of macromolecules decreases with increasing molar mass. Due to cyclization this decrease in density becomes less or even disappears because the macromolecules of higher molar mass are more strongly contracted than those of lower molar mass. After a certain conversion of pendant vinyl groups, the influence of the intermolecular reaction on [r ]... 

Microgels are distinguished from linear and branched macromolecules by their fixed shape which limits the number of conformations of their network chains like in crosslinked polymers of macroscopic dimensions. The feature of microgels common with linear and branched macromolecules is their ability to form colloidal solutions. This property opens up a number of methods to analyze microgels such as viscometry and determination of molar mass which are not applicable to the characterization of other crosslinked polymers. 

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