Polymers polyethylene imine

P 66] Equal streams of 1 mM solutions of fluorescein-labeled polymer (polyethylen-imine, molecular weight 500 000) in water-glycerol mixtures (0 and 80% glycerol) and a clear solution were injected into the channel [44], The flow was achieved by compressed air at constant pressure. Imaging was achieved by applying a confocal fluorescence microscope. 

Water-soluble polymers and polyelectrolytes (e.g., polyethylene glycol, polyethylene imine polyacrylic acid) have been used success-hilly in protein precipitations, and there has been some success in affinity precipitations wherein appropriate ligands attached to polymers can couple with the target proteins to enhance their aggregation. Protein precipitation can also be achieved using pH adjustment, since proteins generally exhibit their lowest solubility at their isoelectric point. Temperature variations at constant salt concentration allow for frac tional precipitation of proteins. 

A further approach to electrically wire redox enzymes by means of supramolecular structures that include CNTs as conductive elements involved the wrapping of CNTs with water-soluble polymers, for example, polyethylene imine or polyacrylic acid.54 The polymer coating enhanced the solubility of the CNTs in aqueous media, and facilitated the covalent linkage of the enzymes to the functionalized CNTs (Fig. 12.9c). The polyethylene imine-coated CNTs were covalently modified with electroactive ferrocene units, and the enzyme glucose oxidase (GOx) was covalently linked to the polymer coating. The ferrocene relay units were electrically contacted with the electrode by means of the CNTs, and the oxidized relay mediated the electron transfer from the enzyme-active center to the electrode, a process that activated the bioelectrocatalytic functions of GOx. Similar results were observed upon tethering the ferrocene units to polyacrylic acid-coated CNTs, and the covalent attachment of GOx to the modifying polymer. 

The PEO salt complexes are generally prepared by direct interaction in solution for soluble systems or by immersion method, soaking the network cross-linked PEO in the appropriate salt solution [52-57]. Besides PEO, poly(propylene)oxide, poly(ethylene)suceinate, poly(epichlorohydrin), and polyethylene imine) have also been explored as base polymers for solid electrolytes [58]. Polyethylene imine) (PEI) is prepared by the ring-opening polymerization of 2-methyloxazoline. Solid solutions of PEI and Nal are obtained by dissolving both in acetonitrile (80 °C) followed by cooling to room temperature and solvent evaporation in vacuo. Polyethyleneimine-NaCF3S03 complexes have also been explored [59],... 

Let us finally mention polymers such as polyethylenoxide (PEO) or polyethylen-imine (PEI), in which NH4HS04 is dissolved (see also Section 15.5). Proton conducting films can be prepared with these materials. Although their conductivity is again relatively low, it is higher than that of pure PEO or PEI salts. 

A titration curve determined in 0.03 M NaCl at room temperature has been reported in the case of cro s-linked PVA 62). The shape of the curve is similar to that of the linear polymer. Cr< >< s-linked resins of polyethylene imine structure have been used to complex heavy m, tal ions from dilute solutions. The complex formation of these resins with metal ions was not thoroughly studied on a thermodynamic basis however, the authors 63) demonstrated that, from a practical point of view, at least one of these resins in column operations was able to concentrate Cu2+, Co2+ and Ni2+ from aqueous solutions, even in the presence of high concentrations of alkali- and alkaline earth metals. 

And similarly (176) 2-phenyl-imino-oxazolidine and its tautomer, 2-amino-2-oxazolidine, with cationic catalyst yielded a mixture of poly(ethylene-N-phenyl urea) and a polyethylene imine type polymer ... 

As mentioned above, the preparation of nanogels by addition reactions of functional macromolecular precursors is mainly used for biomedical applications. Thus, the choice of synthetic precursors for microgel formation is restricted to biocompatible materials. Moreover, as most applications are in drug delivery, the molecular weight of the gel precursors should be below the threshold for renal clearance, a value that depends on the molecular architecture and chemical nature of the polymer but that is usually smaller than 30kDa, which is set as the limit for linear PEG [97], Polymers that are mostly used and thus presented in more detail here are PEG, poly(glycidol) (PG), and polyethylene imine) (PEI). 

It was found meanwhile that nearly every slim unbranched polymer chain, such as poly(trimethylene oxide) [224], poly(l,3-dioxolane) [225], poly(tetramethylene oxide) [226], polyethylene imine) [227], poly(3-hydroxy propionate), poly (4-hydroxybutyrate) and poly(6-hydroxyhexanoate) [228,229], poly(butylene succinate) [229], polyadipates [230], nylon-6 [231], and even oligomers of polyethylene [232], form a-CD ICs with channel structures. In all of these cases, inclusion is a heterogeneous process, since the guest polymer and its CD complex are almost insoluble in water. Therefore, extensive sonication had to be applied to accelerate the diffusion process. The polymer was also dissolved in an organic solvent, e.g., nylon-6 in formic acid, and this solution was added to the solution of a-CD [231], Alternatively, a monomer, such as 11-aminoundecanoic acid, was included in a-CD and polymerized to nylon-11 by solid state polycondensation within the channels of the IC. Thus, the IC of nylon-11 was formed under conservation of the crystal packing [233-235],... 

Most polymeric redox reagents have been developed on microporous polystyrene, typically cross-linked with 1% divinylbenzene. Few examples have been reported for macroporous polystyrene, silica or other supports such as high-loaded cross-linked polyethylene imine (Ultraresins). Some problems specific for redox reactions can also arise from the reactivity of the polymer support itself. In cross-linked polystyrene, for example, benzylic positions can be oxidized at elevated temperatures and thus can account for a competing reaction pathway [8], Further reactivities are found for other solid supports as well. 

Polymer-supported equivalents of the widely used organic base 4-(dimethylamino)pyridine (DMAP) were soon developed, but many of their reported applications are as a stoichiometric base. Resin 37 (Scheme 10.10), containing a polyethylene imine) matrix was the first supported system to be prepared. Those materials were more efficient catalysts than DMAP itself, under the same conditions, for the hydrolysis of p-riilropheriyl esters in aqueous solution [175, 176],... 

Some years ago, Malmstrom etal. synthesized water-soluble metal phosphine complexes based on water-soluble polymers [41], In order to have solubility in both an acidic and a basic medium, they prepared two different water-soluble polymers. For the first, they made methyl [4-(diphenylphosphino)benzyl]amine (PNH) react with poly(acrylic acid) (PAA) using dicydocarbodiimide (DCC) as the coupling agent, under strict exclusion of oxygen (25). For the second, they reacted (4-carboxy-phenyl)diphenylphosphine with polyethylene imine (PEI) at room temperature (26). The reduction by sodium borohydride was made in situ, followed by the addition of methanesulfonic add and diethyl ether. Then, the methanesulfonic salt of phosphinated polyethylenimine was predpitated. 

There are two different ways of preparing the simplest polyamine, polyethylen-imine. The first method leads to a commercial polymer. The parent monomer (aziri-dine) is used and the resulting polymer is highly branched due to pronounced chain transfer. The second method, leading to linear polyethylenimine, requires the preparation of polyoxazoline intermediate and is discussed in the next section. 

The coordinative polymer binding of metal phtalocyanines was examined using polymer ligands like polyethylene imine)59, poly (vinylamine)59"61, poly(acrylamide) modified by dipropylenetriamine59 and silicagel modified by y-amino-propyl-triethoxysilan59. ... 

A recent review summarises the most important classes of soluble polymers, comprising supports derived from polyethylenglycol (PEG), polyvinylalcohol, polyethylene imine, polyacrylic acid, polypropylene oxide, cellulose, polyacrylamide to name the commonly used ones. 

Figure 8-20. Hair fiber extension cycled to provide scale lifting and then treated with 3% polyethylene imine and then 3 cycles of wetting and blow drying. Note the severe scale lifting and folding caused by this polymer treatment. Reprinted with permission of the Journal of Cosmetic Science [67].

The structure-reactivity relationship for polyamine derivatives in activated ester hydrolysis was previously established [46]. Polyvinylamine (PVA), linear (LPEI) and branched (41% branching) polyethylene imine (BPEI) as well as their dodecyl- and imidazole-substituted derivatives with an approximate and equal degree of substitution (16-20%) were applied as catalysts. The compoundsp-NPA and 4-acetoxy-3-ni-trobenzoic acid (ANBA) as well as some of their homologues were used as substrates. At an excessive catalyst concentration relative to the substrate concentration, reactions proceeded at pseudo first order. In each series of polymers, the reaction rate constant was increased considerably by substitution of dodecyl (hydrophobic site) by imidazolyl (catalytic center) and when a charged substrate (electrostatic effect) was employed. At an equal degree of substitution, the catalytic activity increased in the following order LPEK PVA < BPEI. 

Relatively short-chained cationic polymers of average molar mass and high charge density are suitable for patch flocculation. Modified polyethylene imines, polyamines, and polyamide-amine-epichlorohydrin resins are in this category. 

Polyethylene imines, PEI, are strongly cationic and strongly branched polymers with a molar mass between 100,000 and 1,000,00 (g/mole)... 

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