Polyethyleneimine preparation, steps

It is usually difficult to add functionalities (i.e., to insert other amphiphilic molecules into a bilayer membrane) to self-assemble a bilayer nanoparticle after its self-assembly in solvents because the assembled bilayer membrane is a thermodynamically stable. If one can controlled the self-assemble phenomena, more complexed nanostrucutres can be achieved, and it will open a new stage of drug/gene delivery system. Bui et al. prepared a bilayer membrane nanoparticle via two-step self-assemblies using a solubility of amphiphilic block copolymer (Fig. 2.1.8) [108], The nanoparticles were composed of a positively charged complex core (siRNA and polyethyleneimine [PEI]) and a capsid-like (bilayer) shell. The preparation processes were divided into two steps (1) an electrostatic... 

In addition to dendrimers, hyperbranched polymers have been used by several groups as soluble supports for catalysts [7, 17]. These supports are polydisperse and randomly branched, and, since they are prepared in a single reaction step, are generally much cheaper materials. Nevertheless, it has been shown that catalysts immobilized on hyperbranched polymers may possess similar properties as dendritic systems [18]. Therefore, dendritic catalysts serve as ideal model systems for catalysts attached to hyperbranched polymers. We functionalized several hyperbranched polyethyleneimines (PEIs) employing the peptide coupling protocol in reactions with the pyrphos linker system. The pyrphos-rhodium complexes bound to the hyperbranched polymers were also found to be active catalysts for the hydrogenation ofZ-methyl-a-acetamidocinnamate [16]. As observed for the... 

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