Polymeric tubular structures self-assembly

Polymersomes, self-assembled polymer shells composed of block copolymer amphiphiles. These synthetic amphiphiles with amphiphilicity similar to lipids constitute a new class of drug carriers. They are spontaneously formed in aqueous media, as unilamellar vesicles up to tens of microns in diameter. Amphiphilic block copolymers form a range of self-assembled aggregates including spherical, rod-like, tubular micelles, lamellae, or vesicles, depending on polymer architectnre and preparation conditions. Polymers having low hydrophobicity (less than 50%) favor the formation of micelles, however, intermediate level of hydrophobicity (50%-80%) favors the formation of vesicles. Polymeric vesicles, which have a liposome-like structure with a hydrophobic polymer membrane and hydrophilic inner cavity, are called polymersomes. 

RuOj nanotubes have been synthesized by the thermal decomposition of Ru3(CO)j2 inside anodic alumina membranes [248]. Transition metal oxide nanotubes have been prepared in water using iced hpid nanotubes as the template [249]. Self-assembled cholesterol derivatives act as templates as well as catalysts for the sol-gel polymerization of inorganic precursors to give rise to double-walled tubular structures of transition metal oxides [250]. Hydrothermal synthesis of single-crystalline y-Fefi ... 

Another template-free method for the formation of self-assembled tubular structures has been shown by Jiang and co-workers. They used polymeric Janus particles prepared from mixed-shell micelles (MSMs) that self-assembled into tubular superstructures and nanosheets. The micelles were prepared by non-covalent cross-linking of poly(acrylic acid) (PAA) blocks by addition of 1,2-propanediamine (PDA) in DMF (A on Figure 5.45). The two block copolymers were composed of hydrophilic poly(ethylene... 

The self-assembly of natural and synthetic multifunctional unimers occurs, in fact, by a combination of classical molecular recognition and growth mechanisms. Self-assembled, reversible structures include linear, helical, columnar, and tubular polymers micelles monolayers and three-dimensional phases and networks. Self-assembled systems based on an interplay between covalent chains and supramolecular interactions are also important. Typical examples are side-chain SPs (Chapter 5), host-guest polymeric composites and dendrimers (Chapters 2 and 7), polymers with mechanical bonds (Chapter 8), and block copolymers (Chapters 9-11). 

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