Hybrid linear-dendritic block

Gitsov 1, Frechet JMJ. Solution and solid-state properties of hybrid linear-dendritic block copolymers. Macromolecules 1993 26 6536-6546. 

For polymer chemists it is interesting to know how well-known linear polymers can be linked with dendritic architectures and what the supramolecular consequences of this approach might be. Combination of dendrimers with linear polymers in hybrid linear-dendritic block copolymers has been employed to achieve particular self-assembly effects. Block copolymers with a linear polyethylene oxide block and dendritic polybenzylether block form large micellar structures in solution that depend on the size (i.e., the generation) of the dendritic block [10]. Amphiphilic block copolymers have been prepared by the combination of a linear, apolar polystyrene chain with a polar, hydrophilic poly(propylene imine) dendrimer [11] as well as PEO with Boc-substituted poly-a, -L-lysine dendrimers, respectively [12]. Such block copolymers form large spherical and cylindrical micelles in solution and have been described as superamphi-philes and hydra-amphiphiles , respectively. 

Some of the hybrid linear-dendritic block copolymers have been subjected to a thorough characterization in solution [48,55] and in the solid state... 

The solution properties of hybrid-linear dendritic polyether copolymers are investigated by SEC with coupled viscometric detection from the same authors [12]. The results obtained show that the block copolymers are able to form monomolecular and multimole-cular micelles depending on the dendrimer generation and the concentration in methanol-water (good solvent for the linear blocks). 

T., Hult, A., and Malkoch, M. (2013) Multifunctional Poly(ethylene glycol) synthesis, characterization, and potential applications of dendritic-linear-dendritic block copolymer hybrids. Macromolecules, 46 (10), 3726-3736. 

Osano et al. [162] reported the synthesis of hybrid linear-dendritic ABA -type architectures, where A and B were hb poly(ether ketone)s and linear poly(ether sulfone)s, respectively. They prepared an AB2 monomer [3,5-bis(4 -fluorobenzoyl) phenol] to construct the hb segments, in an attempt to provide better control of the resultant hb structures than by utilizing the A2 + B3 approach. The monomer combination of linear block and AB2 monomer for the formation of ABA-type architecture are shown in Table 4, entry 4. Unreacted terminal groups of the ABA polymers were capped by teri-butylphenol and sodium 4-hydroxybenzene sulfonate. Such a flexible approach could allow different functional groups on the polymer chain ends simply by replacing the functional group on the phenol in the last part of the synthesis. 

Dendritic growth hybrids are prepared using one or more functional groups of a preformed linear chain to effect the stepwise growth of one or more dendritic blocks via divergent synthesis. 

Walter, M.V., Lundberg, P., Hult, D., Hult, A., Malkoch, M. A one component methodology for the fabrication of honeycomb films from biocompatible amphiphilic block copolymer hybrids a linear-dendritic-linear twist. Polym. Chem 4, 2680-2690 (2013)... 

This chapter will not attempt to present encyclopedic coverage of the field, but it will only provide representative examples of the processes used to access each of the main types of hybrid block architectures, then it will take a somewhat closer look at specific families of amphiphilic or electroactive hybrid dendritic-linear macromolecules with broad potential for practical applications. 

Its design versatility, as generic dendrons may be prepared to be used later as building blocks in conjunction with other reactive molecules, or coupled to a multifunctional core to afford functional dendrimers, dendritic-linear hybrids, dendronized polymers, etc. This may be a particularly significant advantage if the coupled reactive or core molecule is itself sensitive to the reaction conditions used in the multiple steps of the iterative synthesis of a dendrimer. 

It is also possible to introduce polymerizable groups at the focal point of dendritic macromolecules and a number of authors have demonstrated the synthesis of novel hybrid dendritic-linear block copolymers by this methodology [69-73]. Initial experiments in the use of the dendritic macromonomers involved the preparation of a series of polyether dendrimers, such as the third generation derivative, 37, which contains a single styrene at its focal point [74]. Copolymerization of 37 with styrene then affords a hybrid block copolymer, 38, in which... 

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