PEI structure

Nakagawa, M., M. Endo, N. Tanaka, and L. Gen-Pei Structures of Xestospon-gin A, B, C and D, Novel Vasodilative Compounds from Marine Sponge, Xestospon-gia exigua. Tetrahedron Lett. 25, 3227 (1984). 

The resolution of these columns for protein mixtures, however, was comparably poor. The peak capacity for human serum albumin was near 3 during 20 min gradient elution. Improvement has been reached by covalent binding of PEI (M = 400-600) onto a 330 A silica of 5 pm particle size [38], The peak capacities of ovalbumin and 2a -arid glycoprotein were 30-40 (tgradienl = 20 min). Enhanced peak capacity and resolution probably were due to the more diffuse structure of PEI coupled to silane moieties than that of strictly adsorbed on silica and cross-linked (see Sect, 2.2). Other applications of covalently adsorbed PEI are discussed in Sect. 4.1. 

Other patent reports covering PDF inhibitors from structural classes different from those discussed above include hydrazides (43) [118], aryl-substituted pyrrolidines (44) [119], benzimidazoles (45, 46) [120-121], hydantoins (47) [122] and oxo-pyrrolidines (48) [123], A prodrug approach utilising PDF has been published by Pei, and patents have been published by NewBiotics, but in this case the compounds of interest are used as substrates rather than inhibitors (49) [124-126]. 

Fig. 17. Chemical structures of anionic amphiphile sodium l,2-bis((tetradecyloxy)carbonyl) ethane-1-sulfonate (2Ci4SNa) and poly(ethylenimine)(PEI).

Figure 17 shows the chemical structures of anionic amphiphile sodium-1,2-bis (tetradecylcarbonyl)ethane-l-sulfonate (2Cj4SNa)[34] and poly(ethyleneimine)(PEI). A benzene/ethanol (9 1)(WV) solution of anionic amphiphile was spread on the pure water surface or the PEI-water solution (lxlO5 unit M in monomer unit, pH=3.2) surface at a subphase temperature, Tsp of 293 K. At this pH, ca. 70 % of nitrogen atom in PEI molecule was protonated[35]. Surface pressure-area(ji-A) isotherms were measured with a microprocessor controlled film balance system. 

Figure 21 shows the schematic representation for the aggregation structure of the 2Ci4S/PEI complex monolayer during the compression. The free energy for the monolayer in an amorphous state is higher than that for the monolayer in a crystalline state atO mN-m1... 

Fig. 21. Schematic representation for the aggregation structure of 2C14S/PEI complex monolayer during the compression.

Pei et al. [412] reported an alternating fluorene copolymer 331 with 2,2 -bipyridyl in a side chain that emitted at 422 nm. Treating this polymer with Eu3+ chelates formed the polymeric complexes 332-334. Their emission was governed by intramolecular Forster energy transfer, whose efficiency depends on the structure of the ligands and the Eu3+ content (Scheme 2.49) [412], The most effective energy transfer manifested itself in a single red emission band at 612 nm for the complex 332 with a maximum intensity achieved at —25 mol% content of Eu3+. 

Figure 16.4 Proposed structures of multilayer films based on avidin-biotin interactions in case of (A) PAMAM (G4) dendrimer, (B) PAA, (C) PEI [62, 63]...

The polymer/SWCNT composites can be used as Scaffolds in tissue engineering. The donor-acceptor interactions can be used to assemble thin polymer/SWCNT films stepwise. This method also can be expended to more thermally and oxidatively stable polymer systems. For example, the P4VP/SWCNT films can be used as scaffolds for the synthesis of novel hybrid structures (Correa-Duaite et al., 2004). The polyethyl-enimine (PEI)-SWCNTs composites were used as a substrate for cultured neurons, and promoted neurite outgrowth and branching (Rouse et al., 2004). Correa-Duarte et al. (2004 Landi et al., 2005) reported that 3D-MWCNT-based networks are ideal candidates for scaffolds/matrices in tissue engineering. 

Fig. 5. Preparation of polymer (PEI) ghosts in a three-step process (a) adsorption (b) stabilization (c) removal of core. These structures were substituted with lauroyl groups and histidyl groups to yield the solid-phase analog of (26).

The initial announcement for the commercial preparation of polyetherimides (PEIs) was made by General Electric in 1982 under the trade name Ultem. The final reaction involves the imidization of a diacid anhydride through reaction with a diamine, here w-phenylenedia-mine (structure 4.62). The ether portion of the polymer backbone results from the presence of ether linkages within the diacid anhydride. 

Polyetherimides (PEI) are polyimides containing sufficient ether as well as other flexibi-lizing structural units to impart melt processability by conventional techniques, such as injection molding and extrusion. The commercially available PEI (trade name Ultem) is the polymer synthesized by nucleophilic aromatic substitution between 1,3-bis(4-nitrophthalimido) benzene and the disodium salt of bisphenol A (Eq. 2-209) [Clagett, 1986]. This is the same reaction as that used to synthesize polyethersulfones and polyetherketones (Eq. 2-206) except that nitrite ion is displaced instead of halide. Polymerization is carried out at 80-130°C in a polar solvent (NMP, DMAC). It is also possible to synthesize the same polymer by using the diamine-dianhydride reaction. Everything being equal (cost and availability of pure reactants), the nucleophilic substitution reaction is probably the preferred route due to the more moderate reaction conditions. 

Pei et al. looked at the structure of the orthorhombic phase of Ba1 xKxBiOs powders by time of flight powder neutron diffraction (59). Neutron diffraction intensities should be considerably more sensitive to oxygen atom positions than are X-ray diffraction intensities for compounds such as this. The structural parameters at 300K for x=0.1 and x=0.2 are presented in Table 5. The crystal structure is the same as that of BaPbOs (Table 2) with small differences in cell parameters and atomic coordinates. The refinements show that the atoms are displaced from the ideal positions by many standard deviations, and the thermal parameters for the oxygen atoms make physical sense. The crystal structure is one in which relatively regular Bi-O octahedra (Bi-O distances... 

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