Pincus blobs

It is very important to notice the difference between the results for ideal and real chains under tension. Ideal chains satisfy Hooke s law with force / linearly proportional to elongation Rf. For real chains the dependence of force/on chain elongation Rfh non-linear with the exponent equal to 3/2 for the Flory value of u — 3/5. This non-linear dependence of force on elongation for real chains was first derived by Pincus and tension blobs are often called Pincus blobs. The differences between real and ideal chains can be clearly seen when we consider the dimensionless stretching force ... 

Consider the Pincus blob picture of stretching an ideal chain, discussed in... 

The translocation starts with the formation of initial Pincus blob (i.e., the first... 

Figure 19 An elongated polymer chain with ree / ee is viewed as a strongly stretched linear sequence of Pincus blobs.

The typical chain conformation in this case can be viewed as a nearly completely stretched string of blobs (so-called Pincus blobs) r Ngi, where Ng the number of blobs, bg is... 

The onset point of the shear thinning effect of PE solution depends on the inverse of the relaxation time of the PE chain [152]. It is interesting to note that the shear thinning effects in the study of Krause were found only for high molecular weight samples, and therefore no exact relaxation time could be determined [152]. Generally, the trend of shear thinning can be explained by an extension of the PE chain by shear force, and the viscosity is proportional to the size of the chain cross section that is exposed to the flow, as defined by the Pincus blob size, and therefore t] [165]. This behavior was explained with a modified Rouse... 

Pincus blobs are induced by subjecting the chain to a tension /. The blob size is set by the requirement kT. The chain statistics below this scale are... 

Our preceding discussion focused on systems described in terms of close packed screening blobs. As was previously stressed, such a picture is inherently associated with multichain interactions. Single chain blobs may also occur in systems incorporating many chains. In such situations it is necessary to allow for the effect of chain-chain interactions. The precise method varies with the details of the system. In the following we present two illustrative examples concerned, respectively, with confinement and with Pincus blobs. 

Figure 3. A stretched brush comprising of chains depicted as strings of Pincus blobs. In distinction to the semi-dilute solution behavior the blobs are not close packed.

Blob Type screening collapse electrostatic Pincus adsorption confinement... 

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