Arborols macromolecules

Since these arborols (111) are comprised of two hydrophilic groups connected by a hydrophobic linkage, they fit the simple definition of a bolaamphiphile a term derived from bolaform amphiphile, originally introduced in 1951 by Fuoss and EdlesonJ128 In 1984, when Fuhrhop and Mathieu 129 reported the synthesis and self-assembly of several bolaamphiphiles, these two-directional surfactant-like macromolecules represented a simple entrance to the bolaamphiphile field this subject has recently been highlighted1130 and reviewed.1131 ... 

Smart cascade macromolecules. From arborols to unimolecular micelles and beyond [G. R. Newkome, G. R. Baker, in Molecular Engineering for Advanced Materials, Eds. J. Becher, K. Schaumburg, Kluwer, The Netherlands, 1995, pp. 59-75]. 

Since 1985, Newkome and co-workers [92-94] have reported the synthesis of related symmetrically branched macromolecules which they refer to as arborols . These macromolecules are highly branched dendrimers which are not amenable to size control as a function of generation in that reiterative chemistry for advancing concentric growth has not been reported. These prototypes have been used successfully for controlling molecular shape and, in some cases, surface moieties. To date, examples of uni-, di- and tri-dendron arborols have been reported [92-94] (see Sect. 5). 

In addition to the repeat unit sequence, another area of current interest in polymer structural control (Fig. 1) may be the spatial or three-dimensional shapes of macromolecules. In fact, the recent development of star [181-184] and graft [185] polymers, as well as starburst dendrimers [126], arborols [186,187], and related multibranched or multiarmed polymers of unique and controlled topology, has been eliciting active interest among polymer scientists. In this section, let us consider the following macromolecules of unique topology for which living cationic polymerizations offers convenient synthetic methods that differ from the stepwise syntheses (polycondensation and polyaddition) [126,186,187]. 

Supermolecules include host-guest complexes [19], but also molecular species such as large ring systems, catenanes, rotaxanes [20], etc. In highly branched macromolecules, called dendrimers or arboroles [21, 21], the building blocks are connected through covalent bonds, yet they are sometimes described as supermolecules. These will not be covered in this book. 

The first example of an iterative synthetic approach toward dendrimers has been reported in 1978 by Vbgtle [3], who called it cascade synthesis . In the mid-1980s, Tomalia [4] and Newkome [5] independently reported the divergent synthesis of two new families of dendrimers poly(amidoamine) and the so-called arborols , respectively. A growing interest on these macromolecules lead in 1990 to the convergent synthesis of aromatic polyether dendrimers by Frechet [6]. The two different synthetic approaches can be explained as follows ... 

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