Polymer folding

Yeh,G.S.Y. A structural model for the amorphus state of polymers folded-chain fringed micellar grain model. J. Macromol. Sci. Phys. B6,465-478 (1972). 

Mena-Osteritz, E. et al.. Two-dimensional crystals of poly(3-alkylthiophene)s Direct visualization of polymer folds in submolecular resolution, Angew. Chem. Int. Ed. 39, 2680-2684, 2000. 

Again, the difference in polarity between the spiro and merocyanine forms (Fig. 14) is enough to cause a significant Tt shift. Figure 15 shows the turbidity profiles of the polymer in different illumination regimens (Fig. 15a) and the photomodulation of polymer folding and unfolding (Fig. 15b,c). 

For small, 3, the effect of can be ignored, and the typical size of polymer varies as AT", where the exponent v takes the valne for SAWs. This is called the swollen state of the polymer. For large P, the polymer folds np like a tangled ball of yarn, in order to minimize the energy —N E. In this phase, called the collapsed phase, the typical size of polymer varies as in d dimensions. 

Further evidence for the existence of a helical conformation for meta-linked CPEs comes from circular dichroism (CD) studies of j-PPE-C02 (Figure 14.10). The basis for this experiment lies in the fact that a helix is an inherently chiral structure. Because the helix is chiral, one would expect that if an enantiomeric excess (ee) of the right- or left-handed forms (the P and M forms) exists in solution, then the CD spectrum would feature a bisignate signal due to exciton coupling of the backbone chromophores which are in a chiral environment [35]. However, when a polymer folds into a helical structure, because the polymer itself is achiral, the ensemble of helically folded polymers exists as a... 

There are two limiting cases for the effects of polymer folding on energy transfer efficiency. Folding of a polymer before excitation into a conformation in which the sensitizers are held within a hydrophobic pocket improves the efficiency of energy migration. This takes place with a large number of intramolecular hops or when bond interactions intervene between the sensitizer and the ultimate trap [93]. If the polymers are flexible, however, they can also bend after photo-excitation to... 

Wittmann JC, Lotz B (1985) Polymer decoration the orientation of polymer folds as revealed by the crystallization of polymer vapors. J Polym Sci, Polym Phys Ed 23 205-211 Wunderlich B, Grebo wig J (1984) Thermotropic mesophases and mesophase transitions of linear, flexible macromolecules. Adv Polym Sci 60/61 1-59 Zhou QF, Li HM, Feng XD (1987) Synthesis of liquid-crystalline polyacrylates with laterally substituted mesogens. Macromolecules 20 233-234... 

There are levels of polymer structure, such as the formation of ordered regions with the polymer folded back onto itself, which we are not considering here. 

Funnel Landscapes Describe Diffusion and Polymer Folding Processes... 

SOLUTION A schematic of these two phases at equilibrium is shown in Figure E6.2A. In its native phase, the polymer folds back over itself with the molecules fonning secondary bonds, as shown in the inset in the lower left of the figure. When it becomes denatured, it unfolds as shown in the upper right. As discussed in Example 6.1, the additional bonding in the native state gives it a lower enthalpy relative to the denatured state however, the native state is also more constrained in movement giving it a lower entropy. 

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