Ionenes polyelectrolytes

Polyelectrolytes have recently found application in the development of pH sensitive liposomal controlled release systems. This application arises from the fact that polyelectrolytes may be used both to stabilize liposomes, and to disrupt liposomes in a pH dependent manner. Although the use of liposomes in oral pharmaceutical compositions has been discussed [424], liposomes generally suffer from poor stability and are therefore prone to leakage of the entrapped active agents. To overcome this problem, several authors have stabilized the liposomes using polyelectrolytes. For example, Tirrell and coworkers have employed ionene [425], and polyethylene imine) [426] to stabilize liposomes. Similarly, Sato and coworkers have studied maleic acid copolymers [427], and Sumamoto and coworkers have studied liposomes [428] coated with polysaccharides. In related work, Kondo and coworkers have emphasized the use of carboxymethyl chitin to produce artificial red blood cells [429-435]. 

Takahashi et al.67) prepared ionene-tetrahydrofuran-ionene (ITI) triblock copolymers and investigated their surface activities. Surface tension-concentration curves for salt-free aqueous solutions of ITI showed that the critical micelle concentration (CMC) decreased with increasing mole fraction of tetrahydrofuran units in the copolymer. This behavior is due to an increase in hydrophobicity. The adsorbance and the thickness of the adsorbed layer for various ITI at the air-water interface were measured by ellipsometry. The adsorbance was also estimated from the Gibbs adsorption equation extended to aqueous polyelectrolyte solutions. The measured and calculated adsorbances were of the same order of magnitude. The thickness of the adsorbed layer was almost equal to the contour length of the ionene blocks. The intramolecular electrostatic repulsion between charged groups in the ionene blocks is probably responsible for the full extension of the... 

Kawaguchi et al.125) prepared an ionene-oxyethylene-ionene (IEI) triblock copolymer with the molecular weight 72 X 103 and measured its surface tension in aqueous KBr. They also determined by ellipsometry the adsorbance and the thickness of the adsorbed polyelectrolyte layer at the air-KBr solution interface as a function of the KBr concentration. The data obtained indicate that this copolymer is surface-active and that the effect of added KBr on the surface tension is stronger than in the case of polyoxyethylene (POE). 

When the degree of neutralization (i.e. the pH of the solution) of a weak polyelectrolyte is changed, the composition of the polyelectrolyte complexes containing a polycation is varied as in the resulting systems of some poly(car-boxylix acid)s-ionenes shown in Fig. 7. On the assumption that the polyelectrolyte complexes are formed upon complete neutralization, their compositions r are denoted by the following equations ... 

Fig, 12 a, b. Effect of ionic strength on the formation of polyelectrolyte complexes (a) Reduced viscosity, (b) transmittance Poly(methacrylic acid) (PMAA) (degree of neutralization of PMAA a = l)-Ionene-type polycation (2X), O PMAA(a = 0.75)-2X, 3 PMAA(a = 0.5)-2X, Poly(acrylic acid) (tz = 1)-2X, A Poly(sodium styrenesulfonate)-2X... 

Fig. 13. Dependence of the composition of the polyelectrolyte complex of poly(methacrylic acid) (PMAA)-ionene-type polycation (2X) on the concentration of the complex O Degree of neutralization of PMAA (a) = 0, ionic strength ( ) = 0, a = 0,fi = 0.01, Aa = l,/i=0, Aa=l,iu = 0.01...

The formation of a water-soluble complex of poly(sodium acrylate) with 5,6 ionen bromide of 3 1 composition has been observed108. Its mass and size are independent of the complex origin and are equal to 660 x 103 and 33 nm respectively. The soluble complex presumably consists of the insoluble nucleus of the equimolar polyelectrolyte complex and adsorbed excess of poly(sodium acrylate) on its surface. The soluble polyelectrolyte complex dissociates at higher ionic strengths (0.05-0.1) whereas the insoluble equimolar complex in the core is still stable and precipitates from the solution. 

A large number of macromolecules complementary to PMAA, namely polyvinylpyrrolidone, polyvinylpyridine, polyacrylamide, poly(vinyl alcohol), poly(ethylene oxide), oligoethylenimine, poly(sodium styrene sulfonate), polycations of the integral type ionen (2X) were used as P2 and P3. The pH of the media strongly influences the studied reactions of complex formation. For example, in PVPy + PVP + PMAA or OEI + PEO + PMAA systems in the add region, where weak polybases are completely protonized and PMAA does practically not dissodate, complexes with hydrogen bonds (PMAA-PVP or PMAA-PEO) are formed. In neutral medium weak polybases are partially ionizated and polyelectrolyte complexes (PMAA-PVPy, PMAA-OEI) are generated. In the alkaline medium formation of complexes has not been observed. 

This pronounced change in the UCST indicates a strong interaction between the two polymers. The addition of the polycation PDMAPAA-Q until R = 0.17 (where R signifies the molar ratio of polyelectrolyte/polyDMAPS) decreases the UCST first from 65 to 15 °C. The mixtures with the cationic ionenes show a similar evolution of the UCST, but also exhibit a minimum at K = 0.1-0.17. Thus, when polycations are added to 23b, the UCST decreases first, then passes through a minimum and increases again. This was attributed to the different geometrical structure of polyelectrolyte complexes (Scheme 19). 

These polymers, having a very high charge density, have been of interest as polyelectrolytes. The reaction has been reported to be bimolecular [208]. In preparing the 3,4-ionene bromide ( r = 3, y = 4) [209] in 4 1 dimethyl formamide methanol at 45°C, the rate coefficient was found to be 0.0243 1 equiv sec . The activation energy was 12.3 kcal mole . 

Attempts have been made to prepare high molecular weight "ionene" cationic polyelectrolytes without success (the highest molecular weight was about 40,000 (4 5, 6). In fact, the molecular weight was reported to be almost inversely proportional to the charge density of the polymer (5). 

The influence of charge density on the catalytic effect can be illustrated by comparing the catalytic activity of 2,4-, 2,6- and 2,10-ionenes with 1 10. These data are compared with results obtained for the VAm-VAl copolymers. The dimensionless linear charge density parameter A of the polycations was calculated according to the rigid rod cell model for polyelectrolytes proposed hy Katchalsky [154]. Activation parameters of thiols in the presence of ionenes and VAm-VAl copolymers at pH 7.8 and T = 298 K are presented in Tkble 6. 

Soluble PVBTMA Cl is prepared in two steps using an emulsion polymerization technique [39], The ionenes and soluble PVBTMA Cl give clear solutions and no solubility problem of these supports occurs, according to the authors. The water-insoluble DTBP is oxidized by O2 gas dissolved in the aqueous phase, where the supported metallophthalocyanine tetrasulfonate is found. The ionenes and polymers used in the reaction mixtures serve not only as a support for the catalysts, but also attract the DTBP due to their organic nature, being of utmost importance for the mass-transfer step of the reaction. Accordingly, the conversions of the reaction were higher for the supported catalysts than for unsupported ones. Polyelectrolyte-... 

High-molecular mass surfactants such as butyl acrylate-butyl methacrylate-methacrylic acid copolymer sodium salts, starburst dendrimers, poly(amidoamines), and diaminobutane-based poly(propyleneimine) as well as cationic polyelectrolytes (ionenes) had all been presented as successful secondary phases for aromatic compounds. The determination of 10 nitrophenols in glycine buffers modified by 3-CD (0-10 mmolL" ) and polyvinylpyrrolidone (PVP) (0.5-2.5% w/v) is an example of application of polymer-based electrolytes to rain, tap, and process water. ... 

Polyelectrolytes having bound ions integrated in the polymer backbone are cahed ionenes. Some ionenes have been studied for their bacteriostatic and bactericidal activity. Ionenes with segments of polypropylene oxide in the backbone have been evaluated as thermoplastic elastomers. 

Hong J D, Jung B D, Kim CH, Kim K. 2000. Effects of spacer chain lengths on layered nanostructures assembled with main chain azobenzene ionenes and polyelectrolytes. Macromolecules 33(21) 7905 7911. 

Toutianoush A, Tieke B. 1998. Photoinduced switching in self assembled multilayers of azobenzene containing ionene polycations and anionic polyelectrolytes. Macromol Rapid Commun 19(11) 591 595. 

Ionenes, also known as polyionenes, are polyelectrolytes with positively charged nitrogen atoms located in the backbone of polymeric chains. This type of polycation was first prepared by Gibbs et al [1], from dimethylamino-n-alkyl halides. The generic name of ionenes was suggested for these salts since the reaction of diamines with dihalides to form polyammonium salts proceeds through ionization of amines [2]. Kern and Brenneisen [3] reported that ionenes are formed by the Menshutkin... 

Catalyst MH-3, prepared from surfactant 6, was more active, and catalyst MH-2, prepared from surfactant 5, was less active than MH-1. We are continuing study of the oxidation kinetics to understand better the mechanism of oxidation. As with soluble poly(vinylamine) and ionene polymers containing CoPcTs, the mechanism does appear to involve Ae thiolate anion, and the rates of reaction are not simply dependent on the first power of CoPcTs concentration. There is evidence for formation of hydrogen peroxide during the CoPcTs-catalyzed autoxidation of mercaptoethanol. 4>5l At this time we do not know if there are significant differences in the mechanisms of autoxidation of mercaptoethanol catalyzed by polyelectrolytes and autoxidation of 1-decanethiol catalyzed by cationic latexes. 

Nevertheless, recent studies on functional ionenes [139,361,364,387,492] demonstrate that ordered organic binary multilayers are possible, provided one of the polyelectrolytes bears groups... 

---