Cauliflower dendrimer

In order to illustrate the assembly of carbosiloxane dendrimers, the smallest core unit will first be considered. A fourth-generation cauliflower dendrimer (Fig. 4.46) was obtained via a repetitive synthetic sequence with the aid of di-chloromethylsilane as hydrosilylation and allyl alcohol as alcoholysis reagent... 

A variety of phosphorus cores can be used. These cores can be di-, tri-, tetra-or hexafunctionalized, enhancing the possibilities to prepare dendrimers of various forms at least for the lower generations ( cauliflower , bow-tie , bolaform, ball shaped). 

Dendrimers, or arborols, or cascade, or cauliflower, or starburst polymers, were first synthesized in the early 1980s [3,4]. In 1985 Tomalia et al. [5] and Newkome et al. [6] presented the first papers dealing with dendrimers. A multitude of dendrimers have been presented in the literature ranging from polyami-doamine [7,8],poly(propylene imine) [9,10], aromatic polyethers [11-13] and polyesters [14, 15], aUphatic polyethers [16] and polyesters [17], polyalkane [18-19], polyphenylene [20], polysilane [21] to phosphorus [22] dendrimers. Combinations of different monomers as well as architectural modifications have also been presented. For example, chirality has been incorporated in dendrimers [23,24]. Copolymers of linear blocks with dendrimer segments (dendrons) [25-27] and block-copolymers of different dendrons have been described [28]. 

De Gennes and Hervet 46 statistically found that these cauliflower polymers 8 (Tomalia s PAMAMs) exhibit restricted idealized growth, also known as dense packing , when the number of generations m = mi, where mi = 2.88 (In P + 1.5). This relates in space to the limiting radius Ru which increases linearly with P monomers. Below this limit, the radius R(M) of the dendrimer, when plotted as a function of molecular weight (M), should increase (m0,2) whereas above this limit (R > Ri), compact structures (R == A/0,33) should result. 

D Gudat. Inorganic cauliflower functional main group element dendrimers constructed from phosphorus- and silicon-based building blocks. Angew Chem Int Ed Engl 36 1951-1955, 1997. 

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