Dendritic comb macromolecule

In 1985, application of this simple dendritic construction to a polymer core, specifically chloromethyl functionalized polystyrene was reported. 139 Another example of the identical procedure was reported 140 except utilizing another polymeric core backbone, derived from a functionalized vinyl ether monomer. These are very early examples of dendritic comb macromolecules. 

Tomalia, D. A., et al. (1991), Comb-burst dendrimer topology. New macromolecular architecture derived from dendritic grafting, Macromolecules, 24,1435-1438. 

At the same time, the macromolecules might be classified according to whether their chains have only one kind of atoms - like carbon - in the backbone (isochains) or different elements (heterochains). Concerning their chain architecture, polymers are subdivided into linear, branched, comb-like, crosslinked, dendritic, or star-like systems. 

As a unique method of controlled/living radical polymerization, ATRP has had a tremendous impact on the synthesis of macromolecules with well-defined compositions, architectures, and functionalities, including star- and comb-like polymers as well as branched, hyperbranched, dendritic, network, cyclic type structures and so forth. 

The field of dendritic architectures, as a general class of macromolecules, has found widespread interest in the past decades. Much has been achieved in the preparation of three-dimensional stractures such as comb- and star-shaped polymers and dendrimers. These materials have comparable physical and chemical properties to their linear analogous that make them very attractive for numerous applications [1-4]. 

Branched macromolecules fall into three main classes star-branched polymers, characterized by multiple chains linked at one central point (Roovers, 1985), comb-branched polymers, having one linear backbone and side chains randomly distributed along it (Rempp et al., 1988), and dendritic polymers, with a multilevel branched architecture (Tomalia and Frechet, 2001). The cascade-branched structure of dendritic polymers is typically derived from polyfunctional monomers under more or less strictly controlled polymerization conditions. This class of macromolecules has a unique combination of features and, as a result, a broad spectrum of applications is being developed for these materials in areas including microencapsulation, drag delivery, nanotechnology, polymer processing additives, and catalysis. 

Later on, such ambient temperature synthesis approach was extended to a variety of organo-substituted phosphoranimines, to directly synthesize polyphosphazenes with controlled molecular weight and low polydispersities, so that PDCP preparation and following chlorine substitution steps were eliminated [26]. Such living cationic condensation polymerization method also allows the preparation of polyphosphazenes with complex structures such as comb, star, and dendritic architectures, as well as block and graft copolymers with organic macromolecules [18]. 

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