Side-chain composition brushes

The extension of brush molecules is caused by excluded volume repulsion of the 2D-adsorbed side chains. Therefore, the length of adsorbed brushes should also depend on the grafting density. Copolymer brushes with a random sequence of methyl methacrylate and poly(n-butyl acrylate)-substituted methacrylate units were prepared with different compositions, i.e., grafting densities. Table 3 com-... 

Because the adsorption of the side chains is such a strong factor in controlling the macromolecular conformation, not only the length of side chains but also their composition is of great importance. This can be demonstrated by comparing the structures for the brush molecules with poly(n-butylacrylate) side... 

The grafting from approach allows one to manipulate the chemical composition of the side chains. In addition to homopolymer bmshes, one can prepare molecular brushes with both random and coaxial or adjacent block copolymer side chains. 

The challenge in the synthesis of molecular brushes lies not so much in the chemical stmcture and composition of the main chain and side chains, but in their relative length scale and how... 

In addition to the side chain conformation, chemically different side chains attached to the same main chain may also have a pronounced impact on the main chain conformation, particularly if the respective side chains are incompatible. Demixing of the side chain is hampered by the fact that the chemically different side chains are bound to the same main chain, leading to highly frustrated single chain structures. In order to experimentally address this point, the phase separation within statistical cylindrical brush copolymers comprising PMMA and poly-2-vinylpyridinium (PVP) side chains was investigated [93, 94]. The samples were prepared by radical copolymerization of methacryloyl end-functionalized PMMA M = 3,700 g/mol) and PVP M = 5,100 g/mol) macromonomers. Copolymer brushes with two different compositions were synthesized and characterized as shown in Table 1. Subsequent quatemization of the PVP side chains with ethylbromide was conducted in order to enhance incompatibiUty. 

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