Periodic Nanodomain Structures

A series of styrene-ferrocenyl dimethylsilane block copolymers form periodic structures on a lengthscale comparable to the size of the polymers.  

Pure diblock copolymers (e.g., see Fig. 8) phase-separate into an equilibrium structure that depends on the corresponding % parameter, the length of the block copolymer, and the volume fraction of the two phases. Knowledge of the % parameter will allow one to target a specific morphology by adjusting the molar mass and composition of the diblock copolymer accordingly. 

Another approach involves the blending of diblock copolymers with the corresponding homopolymer (Fig. 9). Thus, instead of synthesizing a specific block copolymer in order to obtain a certain morphology, it is possible to mix in a corresponding homopolymer to alter the overall composition.  

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A schematic picture of the structure of semi-crystalline PODMA is shown in the insets of Fig. 12.1. Basic idea is that the alkyl groups belonging to different monomeric units form layer-like alkyl nanodomains which are separated by main chains. The periodicity dnps of this lamellar structure reflected by the prepeak in x-ray scattering data is indicated. We assume that the alkyl groups within the alkyl nanodomains are basically interdigitated and not to far away from an extended chain conformation. This can be concluded from the dependence of the d ps value on the number of alkyl carbons per side chain C for atactic poly(n-alkyl methacrylates) (Fig. 12.2). The dependence of dnps on (7 is nearly linear and the slope is about 0.13 nm [50] per additional CH2 unit in the side chain corresponding to the value reported for extended chain alkanes (0.127 nm/carbon). 

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