Amphiphilic copolymer

Alexandridis P, Olsson U and Lindman B 1997 Structural polymorphism of amphiphilic copolymers Six lyotropic liquid crystalline and two solution phases in a poly(oxybutylene)-poly(oxyethylene)-water-xylene system Langmuir 23-34... 

Morishima etal. [29 — 31] prepared amphiphilic copolymers of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) with various hydrophobic comonomers, and studied the tendency of their self-aggregation and the nature of the hydrophobic microdomains thus formed in aqueous solution. Chart 1 shows some of these amphiphilic copolymers. Here, the value of x indicates the mol% content of hydrophobic comonomer units. 

The charged segments of the AMPS units in these amphiphilic copolymers effectively solubilize the sequences of hydrophobic monomer units to water. In fact, the copolymers ASt-72 (7 with x = 72), APh-50 (8 with x = 50), APy-50 (9 with x = 50), and ALa-44 (10 with x = 44) were all soluble in water. The copolymer ACh-x was a little less water soluble ACh-23 (11 with x = 23) was almost soluble, whereas ACh-60 was insoluble. All these copolymers were soluble in methanol, N, AT-dimethylformamide, and dimethylsulfoxide, but insoluble in most of other common organic solvents. 

The formation of a microphase structure leads to a surface-active effect [31]. The surface tension of water is considerably lowered when amphiphilic copolymers are dissolved. The surface-active effect appears more significantly in the copolymers with more hydrophobic units. 

The microphase structure was clearly observed in transmission electron micrographs of the film of amphiphilic copolymers cast from aqueous solutions [29, 31]. An important finding was that no microphase structure was observed for the film cast from organic solutions. This difference indicates that a microphase structure is formed in aqueous solution, but not in organic solution. Different hydrophobic groups showed considerably different morphological features i.e. whether microphase separation leads to a secondary or higher structure depends on the type of hydrophobic units in the copolymers [31],... 

Fig. 1 Vesicle construct formed from poly(L-lysine)-i)-poly(L-leucme) polypeptides where the poly(L-leucine) block corresponds to the a-helical hydrophobic segments and the poly (L-lysine) block corresponds to the random coil hydrophilic segments. Note that this is one specific example and not all vesicle constructs have a-helical and random coil blocks. Moreover, the amphiphilic copolymer can be comprised of either a pure block copolypeptide or a macromolecule consisting of a polypeptide and another type of polymer. Adapted from [20] with permission. Copyright 2010 American Chemical Society...

Meijer et al. [135] further studied aggregation phenomena of amphiphilic copolymers obtained by modifying the termini of the dendrimer units of the above series with carboxylic acid groups (49). TEM experiments indicated that all block copolymers formed large aggregates except third generation copolymer which formed worm-like micelles. 

The direct synthesis of poly(3-sulfopropyl methacrylate)-fr-PMMA, PSP-MA-fr-PMMA (Scheme 27) without the use of protecting chemistry, by sequential monomer addition and ATRP techniques was achieved [77]. A water/DMF 40/60 mixture was used to ensure the homogeneous polymerization of both monomers. CuCl/bipy was the catalytic system used, leading to quantitative conversion and narrow molecular weight distribution. In another approach the PSPMA macroinitiator was isolated by stopping the polymerization at a conversion of 83%. Then using a 40/60 water/DMF mixture MMA was polymerized to give the desired block copolymer. In this case no residual SPMA monomer was present before the polymerization of MMA. The micellar properties of these amphiphilic copolymers were examined. 

Recently, many studies have focused on self-assembled biodegradable nanoparticles for biomedical and pharmaceutical applications. Nanoparticles fabricated by the self-assembly of amphiphilic block copolymers or hydrophobically modified polymers have been explored as drug carrier systems. In general, these amphiphilic copolymers consisting of hydrophilic and hydrophobic segments are capable of forming polymeric structures in aqueous solutions via hydrophobic interactions. These self-assembled nanoparticles are composed of an inner core of hydrophobic moieties and an outer shell of hydrophilic groups [35, 36]. 

Gref R, Rodrigues J, Couvreur P (2002) Polysaccharides grafted with polyesters novel amphiphilic copolymers for biomedical applications. Macromolecules 35 9861-9867... 

Amphiphile-oil-water system, temperature of, 16 424-426 Amphiphiles, 16 420 Amphiphile strength, 6 424 Amphiphilic chemicals, 17 56 Amphiphilic copolymers, 20 482 behavior of, 20 483 well-defined, 20 485-490 Amphiphilic molecules, 15 99-101 Amphiphilic plasticizers, 14 480 Amphiphilic polymer blend, 23 720 Amphiphilic polymers statistical, 20 484-490 stimuli-responsive, 20 482-483 Ampholytes, 9 746-747 Amphoteric cyclocopolymers, water-soluble, 23 721 Amphoteric starches, 4 722 Amphoteric (zwitterionic) surfactants, 24 148... 

Micelles from Amphiphilic Copolymers in Organic Solvents. 85... 

AB block copolymers containing two water-soluble blocks are often referred to as double-hydrophilic block copolymers. These copolymers have spurred much interest in recent years because they can generally be transformed into amphiphilic copolymers once an adequate stimulus is applied. In other words, one of the hydrophilic water-soluble blocks can be transformed into a hydrophobic block whenever a given property of the aqueous medium is changed. Since these copolymers may contain one or two polyelectrolytic blocks, the typical features of polyelectrolytes described in Sect. 4.2 should also be considered for some double-hydrophilic block copolymers. 

PEO chains have been grafted to this backbone, leading to an amphiphilic copolymer. Aqueous micelles have been then prepared from these copolymers [332]. 

Weener et al. prepared photo-responsive monolayers from azobenzene modified polypropylene imine) dendrimers which also hold promise in the area of optical data storage [74], A fifth generation polypropylene imine) dendrimer was functionalized with equal amounts of palmitoyl and azobenzene containing alkyl chains, resulting in the formation of an amphiphilic copolymer with a random shell structure (Figure 16.5). 

P. Perrin Amphiphilic Copolymers A New Route to Prepare Ordered Monodisperse Emulsions. Langmuir 14, 5977 (1998). 

Gautier S, D Aloia V, Halleux O, Mazza M, Lecomte P, Jerome R (2003) Amphiphilic copolymers of e-caprolactone and y-substituted-e-caprolactone. Synthesis and functionalization of poly(D,L-lactide) nanoparticles. J Biomater Sci Polym Ed 114 63-85... 

Fig. 25. Preparation of amphiphilic copolymer membrane with hydrophilic and hydrophobic side chains...

Polymeric micelle formation occurs as a result of two forces. One is an attractive force that leads to the association of molecules while the other one, is a repulsive force, preventing unlimited growth of the micelles to a distinct macroscopic phase (Price, 1983 AstaLeva et al., 1993 Jones and Leroux, 1999). Amphiphilic copolymers form micellar structures through self-association of the insoluble segments when placed in a solvent that is selective for the other monomer (Kataoka et al., 1993 Jones and Leroux, 1999). The process of micellization for amphiphilic copolymers is similar to the process described for conventional hydrocarbon chain-based surfactants as described in the Lrst part of this chapter. 

Schild, H. G. and D. A. Tirrell. 1991. Microheterogenous solutions of amphiphilic copolymers of N-isopropylacrylamide, An investigation via uorescence metltanhgmuir.7 1319-1324. 

Peracchia, M., et al. 1998. Pegylated nanoparticles from a novel methoxypolyethylene glycol cyanoacrylate-hexadecyl cyanoacrylate amphiphilic copolymer. Pharm Res 15 550. 

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