Helical Homopolymerizations

The property of the polymers in question to form nonspherical nanostructures was confirmed in experimental studies. Shih et al. [29] synthesized alternating copolymers of 1-alkenes with maleic anhydride. The maleic anhydride units were hydrolyzed to maleic acid units. Fully hydrolyzed macromolecules associated into microstructures of cylindrical and ellipselike shape. The cylindrical shape was characteristic of copolymers with octadecene and hexadecene moieties, while the copolymers with lower alkene copolymers (tetradecene, dodecene, decene, octene) formed ellipsoidal structures. Wataoka et al. [30] investigated the formation of nonspherical helices in a system of maltopentaose-carrying polystyrene (PS). The polymer was synthesized via the homopolymerization of vinylbenzyl maltopentaose amide (Scheme 3). 

Alternate Helical Structures. Since Pauling and Corey s description of the a helix [76], many other helical structures for polypeptides have been proposed and described. However, most of them are rare or found only in homopolymeric systems. These include the helix, the it helix, and the an helix. 

On the basis of the difference in optical rotation between copolymer and homopolymeric mixture having the same composition the molar optical rotation referred to one monomer residue of 4-methyl-l-pentene has been evaluated (Table XIX). This last increases in absolute value with increasing content of units derived from the optically active monomer and reaches an asymptotic value when the above content is larger than 50%. The optical rotation of 4-methyl-l-pentene units thus obtained can be of the same order of magnitude as that evaluated according to Brewster, assuming that these units are inserted in one screw sense helical chain. 

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