Side-chain ordering

Fig. 35. Effect of water on parvalbumin dynamics. Time constants (tI) were determined from time correlation functions for the vector between the two outermost nonhydrogen atoms in each side chain, ordered by residue type. (Top) In vacuo simulation of parvalbumin (bottom) simulation with waters. From Ahlstroem etal. (1987).

It is difficult to control the stereoregularity of polymers in radical telomerization. However, the side chain ordering in the polymer can be realized if a long-chain alkyl compound is chosen as a vinyl monomer for telomerization. A preliminary example is reported with poly(octadecyl acrylate), ODA . The resultant polymer can be easily grafted onto porous silica through a terminal trimethoxy-silyl group. Toluene and tetrachloromethane are good solvents for this procedure. 

Sil-ODA has been developed to address this question.The ODA phase does not make lipid membrane structures in an aqueous system, but it possesses similar functions, such as side-chain ordering and phase transition behavior between ordered and disordered states. However, the resultant selectivity in HPLC often excelled, better than expected. This is due to a sort of a side effect and, then, it may be called a polymeric effect, which promotes multiple interactions to increase the selectivity. Molecular ordering of functional groups particularly enhances it. 

PAHs. This cannot be explained only by the increase of side-chain ordering, because it seems that there is no significant difference in the phase transition behavior between Sil-ODA and Sil-co-ODA in the mobile phase, as detected by differential scanning calorimetry (DSC) and suspension-state Therefore, we focus on the... 

In this chapter we describe results of TOF measurements on aliphatic polysilylenes and poly(di-n-butylgermylene) carried out over a broad range of temperature encompassing the glass transition temperature Tg, and the phase I - phase II (order - disorder) transition caused by side chain ordering and melting, which is accompanied by a blue shift in the uv spectra of the polymers. 

The polysilylenes continue to be of interest because of the novel electronic and optical properties of these macromolecules. These properties stem from the presence of a o-delocalized -Si-Si- polymer backbone. The interplay between conformational states, side-chain order/disorder transitions, and electronic states creates interesting temperature and pressure dependent optical phenomena. These novel properties have stimulated interest in improved synthetic methods. Thus, the first three papers in this symposium focus on understanding and improving catalytic methods for generating silylene chains. These efforts are followed by Worsfold s research on improving the traditional Wurtz coupling method of synthesis. 

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