Linear chain attachment

The above observations are consistent with the comparisons described in Sect. 3.4.2, which show that as for cyclic ZCR(CH2)n liquids is uniformly greater than that of the corresponding linear ZCRH(CH2)nH liquid, and that the magnitude of the difference is markedly greater than that expected on the basis of decreased steric hindrance owing to cyclization of the linear chain attached to substituent Z. This enhanced adsorptivity is not unique to alpha-substituted alkanes it appears... 

Figure 1 Macromolecular architectures linear macromolecular chains (homopolymer, block-copolymer and statistical copolymer [14]), brushed-polymer (= linear chains attached to a polymer-chain brush-polymer, brush-copolymers [14]), star polymer [4], mikto-star-polymer [16], arborescent graft polymer (=repeated grafting of linear chains on a macromolecule [17,18]), dendrimer (= maximally branched, regular polymer [15])...

In 21, the longest unbranched chain is 17, and there is a methyl substituent and an ethyl substituent. Using the rule that substituents are arranged alphabetically, 21 is a 13-ethyl-5-methylheptadecane. However the group at C8, in the box, is a complex substituent. The point of attachment on the 17-carbon linear chain is at C8, and there is a four-carbon linear chain attached to C8. The butyl substituent is numbered, beginning from the point of attachment, and that carbon is labeled Cl. Therefore, 21 is a 8-butyl-13-ethyl-5-methylheptadecane. However, the butyl substituent has methyl substituents. The carbon attached to C8 is numbered 1. The butyl side chain, in the box, has three methyl groups attached at Cl and C3 as the side chain is numbered. The complex side chain is therefore a 1,1,3-trimethylbutyl, and the entire unit is attached to C8 of the heptadecane. The final name of 21 is 8-(l,l,3-trimethylbutyl)-13-ethyl-5-methylheptadecane. 

The amount of branching introduced into a polymer is an additional variable that must be specified for the molecule to be fully characterized. When only a slight degree of branching is present, the concentration of junction points is sufficiently low that these may be simply related to the number of chain ends. For example, two separate linear molecules have a total of four ends. If the end of one of these linear molecules attaches itself to the middle of the other to form a T, the resulting molecule has three ends. It is easy to generalize this result. If a molecule has v branches, it has v 2 chain ends if the branching is relatively low. Branched molecules are sometimes described as either combs or... 

The relationship between 20 and reserpine (1) is close like reserpine, intermediate 20 possesses the linear chain of all five rings and all six stereocenters. With the exception of the 3,4,5-tri-methoxybenzoate grouping, 20 differs from reserpine (1) in one very important respect the orientation of the ring C methine hydrogen at C-3 in 20 with respect to the molecular plane is opposite to that found in reserpine. Intermediate 20 is a reserpate stereoisomer, epimeric at position 3, and its identity was secured by comparison of its infrared spectrum with that of a sample of (-)-methyl-O-acetyl-isoreserpate, a derivative of reserpine itself.9 Intermediate 20 is produced by the addition of hydride to the more accessible convex face of 19, and it rests comfortably in a conformation that allows all of the large groups attached to the D/E ring skeleton to be equatorially disposed. 

Star shaped macromolecules are polymers, where the one end of f > 2 (f functionality of the star) linear chains is chemically attached by covalent bonds to a small central linker unit, are the simplest form of branched polymers. Modern anionic polymerization techniques allow us to synthesize star systems with a large number of nearly monodisperse arms [133, 134],... 

Poly(macromonomers) with moderately long side chains attached to every few (second) atom along the backbone are very densely branched polymers. When the degree of polymerization of the backbone is low then the poly(macromon-mers) tend to resemble star polymers [39, 40]. When the degree of polymerization is very high the poly(macromonomer) acquires a cylindrical conformation (bottlebrush), due to the stretching and linearization of the backbone [40]. 

The terminal units of a dendrimer are extended predominately towards the exterior of the dendrimer [43]. While some terminal units may fold inwards, most of the terminal units are on or near the outside perimeter. Combined with the fact that there is a narrow interface on the outside of large dendrimers [17], most terminal groups should be accessible for chemical manipulation such as attachment to surfaces, mounting of catalysts or attachment of linear chains. 

The simplest structure is that of / linear chains of exactly the same length attached to an/-functional central unit - see Fig. 1... 

PFCs comprise a large group of compounds characterized by a fully fluorinated hydrophobic linear carbon chain attached to one or more hydrophilic head. PFCs repel both water and oil, and are therefore ideal chemicals for surface treatments. These compounds have been used for many industrial applications including stain repellents (such as Teflon), textile, paints, waxes, polishes, electronics, adhesives, and food packaging [1]. 

Macromolecule containing a single branch point from which linear chains (arms) emanate. Note 1 A star macromolecule with n linear chains (arms) attached to the branch point is termed an n-star macromolecule, e.g., five-star macromolecule. 

---