Amphiphilic polymers formation

In addition to utilizing natural ODNs in block copolymers, ODN mimics have also been studied using polymers with the capability of forming hydrogen bonds. Bazzi and colleagues (Bazzi and Sleiman 2002 Bazzi et al. 2003) have reported diblock and triblock amphiphilic polymers with diamidopyridine (DAP) and dicarboximide moieties as molecular recognition units and studied their micelle formation properties (Chart 2.4). 

Water Solutions of Amphiphilic Polymers Nanostructure Formation and Possibilities for Catalysis... 

A polymer with different hydrophilic and hydrophobic parts are necessary for monolayer formation on a water subphase, this corresponds to an amphiphilic polymer, a type of polymers frequently used to prepare mono- and multilayers [54,55], This situation can be illustrated in Fig. 3.6, for a short molecule as stearic acid. 

Colloid stabilization with amphiphilic polymers [2,114,115] requires the formation of a thick polymer layer around each particle in order to create a repulsive steric force that overcomes the van der Waals attraction. This is usually done by adsorbing on the colloidal particle a polymer solution in a good solvent, which builds up on the surface a fluffy layer with a thickness of the order of the radius of gyration of isolated polymer chains, in general of the order of a few hundred angstroms. 

Moreover, the amphiphilic nonchiral polymer PG-0C(0)Ci5H3i was used by Mecking and coworkers in the preparation of nanometer-sized stable palladium colloids using PdCl2 or Pd(OAc)2. The formation of these palladium colloids was visualized by transmission electron microscopy and in the case of the amphiphilic polymer prepared from a PG scaffold of DPn = 63, a colloid of 5.2 1.8 nm average particle size was obtained. The... 

Hydrophobically modified polybetaines combine the behavior of zwitterions and amphiphilic polymers. Due to the superposition of repulsive hydrophobic and attractive ionic interactions, they favor the formation of self-organized and (micro)phase-separated systems in solution, at interfaces as well as in the bulk phase. Thus, glasses with liquid-crystalline order, lyotropic mesophases, vesicles, monolayers, and micelles are formed. Particular efforts have been dedicated to hydrophobically modified polyphosphobetaines, as they can be considered as polymeric lipids [5,101,225-228]. One can emphasize that much of the research on polymeric phospholipids was not particularly focused on the betaine behavior, but rather on the understanding of the Upid membrane, and on biomimicking. So, often much was learnt about biology and the life sciences, but little on polybetaines as such. 

In most cases, the amphiphilic polymers do not exhibit intrinsic fluorescence and therefore a dye needs to be encapsulated, or the vesicle membrane has to be stained. The first method requires encapsulation of a water-soluble fluorescent dye during vesicle formation followed by a subsequent exclusion of the dye from the extracellular space (e.g., by size exclusion chromatography, dialysis, ultrafiltration, or centrifugation). To stain the membrane either a fluorophore is covalently linked in a certain percentage to the membrane forming molecules, or a lipophilic probe is aggregated in the hydrophobic part of the membrane [116,146,175,176],... 

Control of the micelle size utilized in the formation of PAn nanoparticles has been achieved by tailoring the stabilizer to modify the resulting micelle dimensions. Kim and coworkers215 216 used amphiphilic polymer molecules and hydrophobically end-capped polyethylene oxide) [PEO], and varied the hydrophilic regions in it to control the final micelle size. The resultant nanostructures ranged from 20 to approximately 300 nm in size, depending on the molecular weight of the hydrophilic PEO midsection. 

There are basically two topics that need to be addressed regarding the effect of amphiphilic polymers on the physical behaviour of microemulsions. The first topic is related to phase behaviour and structure formation. Amphiphilic polymers can strongly influence phase behaviour because of their impact on the bending rigidity of the surfactant film. For both droplet micro emulsions and bicontinuous microemulsions such phenomena were studied. Especially in droplet microemulsions, amphiphilic polymers were used to interconnect microemulsion domains. This leads to ordering phenomena and can alter the phase behaviour. The second topic again is based on systems where microemulsion domains are connected via polymers. It covers dynamic phenomena with a focus on viscoelastic properties. Important in this area is the formation of transient or permanent networks. 

Porcar I., Gareil R, Tribet C. Formation of complexes between protein particles and long amphiphilic polymers binding isotherms versus size and surface of the particles. J. Phys. Chem. B 1998 102 7906-7909. 

Vinyl ethers with isobutyl-, acetoxy ethyl-, and malonate ethyl- pendant groups have been used. Hydrolysis of the pendant groups in the last two cases led to the formation of amphiphilic polymers [50,261-264]. It is obvious that this approach is analogous to the DVB method discussed above, and therefore it suffers the same disadvantages (poor control of the number of the arms, architectural limitations, etc.). Unfortunately detailed characterization data were not provided in these studies. 

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