Degree quatemization

Kabanov etal.123 hydrolyzed 44 (PNPA) and 56 (NABA) in the presence of QPVP. They found that the hydrolysis rate decreased with increasing degree of quatemization in water. A bell-shaped dependence was observed for 56 (NABA) in alcohol-aqueous media (see Fig. 13). Recently, Cho and Morawetz discussed the hydrolyses of a polymer substrate by a pyridine-containing polymer124. ... 

As is dear from Fig. 14, the catalytic activity of quatemized resin is in the order, RC2PVP > RBzPVP > 88 (RC16PVP). This implies that the catalysis depends mainly on the hydroxide ion in the resin domain, because the degrees of quaterni-zation change in the same order as that of the catalytic activity. 

Fig. 14 PG architecture decorated with PEG chains and tris(2-aminoethyl)amine with different degrees of quatemization. Reproduced with permission from [129]. Copyright 2006 Elsevier...

Snyman, D., Hamman, J. H,. Kotze, J.S., Rollings, J.E. and Kotze, A.F. (2002) The relationship between the absolute molecular weight and the degree of quatemization of /V-trimethyl chitosan chloride. Carbohydr. Polym. 50 145-150. 

Thanou, M.M., Kotze, A.F. Scharringhausen, T., LueBen, H.L., de Boer, A.G., Verhoef, J.C. and Junginger, H.E. (2000a). Effect of degree of quatemization of A-trimethyl chitosan chloride for enhanced transport of hydrophilic compounds across intestinal Caco-2 cell monolayers. J. Control. Release 64 15-25. 

Fig. 4. Potentiometric - - and viscosimetric -O- titration curves using HC1 as titrating reagent ( 3 = degree of protonation of residual tertiary amine groups 5 = overall degree of neutralization e = degree of neutralization of quaternary ammonium hydroxide sites) of partially quatemized poly[thio-l-(N,N-dimethyl-aminomethyl)ethylene]...

The compounds prepared and characterized in our laboratories can aU be described as salts of quatemized nitrogen cations combined with a variety of anions. The pyr-roUdinium family of cations, in particular, shows rich phase behavior in the solid state. The anions themselves often possess some degree of rotational symmetry, and the degree of plasticity is certainly dependent on the nature of the anion as well as the cation, as discussed later. 

Among all the quatemized chitosans described into literature, W,W,W-trimethyl chitosan chloride (TMC) is the most widely applied for gene therapy applications [28, 33, 34]. The quatemization maintained and improved the muco-adhesive properties of chitosan, depending on the quatemization degree, which makes this chitosan derivative an ideal candidate for gene delivery [23]. Typically, TMC can be synthesized by reaction of chitosan with methyl iodide in the presence of sodium hydroxide into A-methyl-2-pyrrolidinone at 60 °C. In a second step, the iodide ion is substituted by chloride by an ion exchange process [34] (Fig. 2). 

The differences in reactivities in poly(vinyl alcohol)s between isotactic meso) and syndiotactic (trans acetals [26-28] is another example. In extending this to model compounds, reactions of stereo isomers of pentane-2,4-diol and heptane-1,4,6-triol with formaldehyde take place much faster for the meso than for the dl-diol portions [26-28]. Even more important are the steric effects imposed by restricted rotations. For instance, quatemizations of chloromethylated polyether sulfmies exhibit decreasing rates at high degrees of substitution. This can be attributed to restricted rotations of the polymeric chains, because this phenomenon is not observed with more flexible chloromethylated polystyrene under identical conditions [23, 24]. 

Techniques for chloromethylating polyarylether sulfones, polyphenylene oxide, phenolic resins, and model compounds were described recently [191]. When the subsequent products are cmiverted to quaternary amines, there is a decrease in the quatemization rate with increase in degree of substitutimi. This may be due to steric effects imposed by restricted rotation of the polymeric chains [191]. This phenomenon was not observed in quatemization of poly(chloromethyl styrene). The chloromethylation reaction of a polysulfone with chloromethyl ether, catalyzed by stannic chloride, can be illustrated as follows ... 

Later, some attempts were made to quantify the curvature of sample 21PVP47-co-79PMMA44 as function of the degree of quatemization and of the quatemization agent, i.e., ethyl versus benzyl bromide [94]. With increasing degree of quatemization of the PVP side chains, the curvature radius varies from/ .urv = 27 run... 

Fig. 25 Inverse radius of curvature determined from AFM pictures as function of the degree of quatemization for sample 21PVP47-co-79PMMA44. QBB degree of benzylation, QEB degree of ethylation. Data taken from [94]...

Given that poly(l-vinylimidazole) (PVIm) has a pATa of around 5.5, this polymer does not complex DNA at physiological pH. Thus, Allen et al. quatemized the imidazole ring with various substituents such as bromoethanol in order to obtain permanently charged imidazolium-containing copolymers [107]. As the quatemization degree was increased, fewer sites were available for protonation,... 

Quatemized or partially quatemized derivatives of poly(4-vinylpyridine) (DP = 1,600, Mw = 168 kDa) were synthesized by the group of Izumrudov [210]. Among them, four different series were synthesized quartemized poly(4-vinylpyridine) with V-alkyl ester substituents (C -PVP, Fig. 20b), polycarboxybetaine with alkyl spacer (C -PCB, Fig. 20c), poly[(4-vinylpyridine)-co-(V-alkyl-4-vinylpyridinium)] and poly[(iV-methyl-4-vinylpyridine)-c )-(V-alkyl-4-vinylpyridinium)] both with various alkylation degree p (respectively Cn-PVP-p, Fig. 20d and Me-Cn-PVP-p, Fig. 20e). Unfortunately, relatively few comparisons between these polymers were presented in this publication regarding the physico-chemical characteristics of their polyplexes. At a charge ratio of 5, Cn-PVP-based polyplexes with short V-alkyl... 

Juan AS, Letoumeur D, Izumrudov VA (2(X)7) Quatemized poly(4-vinylpyridme)s as model gene delivery polycations structure-function study by modification of side chain hydrophobicity and degree of alkylation. Bioconjug Chem 18 922-928... 

The multicomponent biofluid blood consists, among other components, of proteins and cells and still represents a challenge for interaction studies with PEC particles. A comprehensive study on the interaction of complexes of PDMAEMA and either a crosslinked CHT or poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPSNa) with human blood from healthy volunteers was reported by Yancheva et al. [176]. Thereby, PDMAEMA complexed with CHT no longer caused inherent cytotoxicity compared with the uncomplexed state, but haemostatic activity was still present. However, PEC of PDMAEMA/PAMPSNa featured both low cytotoxicity and low haemostatic activity. The degree of PDMAEMA quatemization had an additional influence on both blood compatibility parameters. In particular, the authors claimed a higher interaction of samples containing higher quatemized PDMAEMA with the cell walls of blood cells (both red and white) because of electrostatic attraction to the anionic compounds of their cell membranes. 

Solid-state CP MAS NMR spectroscopy has been applied to determine the average degree of quatemization of the acetate salt of N,N,N-trimethylchitosan. ... 

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