Molecular weight of cationics

ISiKe caibenium ions are extremdy reactive intermediates and the molecular weights of cationically produced polymers are by and large determined by chain transfer to monomer, cxie can ne ect kt and kx in the deimminator. Thus by rearranging Eq. (11), one obtains ... 

Accordingly, the molecular weight of cationic polymers calculated from viscosity measurements corresponds to one basic group per macromolecule [184]. The number of polymer molecules (as well as of basic groups) is very close to the initial initiator concentration and remains constant over a long period, except the very beginning of polymerization [176, 177, 180, 188]. 

Most VP-based copolymers are also characterized by K value. However, the literature on molecular weights of VP copolymers is very sparse. Wu and Senak reported in 1990 (6) the absolute molecular weights of cationic copolymers of quatemized vinyl pyrrolidone and dimethylaminoethyl methacrylate by size exclusion chromatography with low-angle laser light scattering (SEC/LALLS) and SEC with universal calibration (see Table 8). The molecular weights (relative to polyethylene oxide standards) of nonionic copolymers of vinyl pyrrolidone and vinyl acetate, a nonionic terpolymer of vinyl pyrrolidone, dimethylaminoethyl methacrylate, and vinyl caprolactam, and anionic copolymers of vinyl pyrrolidone and acrylic acid were also reported in 1991 (7) by Wu et al. (see Tables 6 and 7). 

Table 9 Intrinsic Viscosities and Absolute Molecular Weights of Cationic PVP/DMAEMA Copolymers in pH 7 Buffer, 0.5 M LiNOj...

CnMIM][Co(C2B9H )2] with = 2, 4, 6, 8, 12, and 14 are viscous at room temperature. With increasing temperature, density, and viscosity decrease. The viscosity depends on the molecular weights of cation and anion, electrostatic forces, van der Waals interactions, hydrogen bonds, or geometry of the anions (Bonhote et al., 1996 Noda et al., 2001 Wasserscheid and Keim, 2000 Wasserscheid and Welton, 2007). 

Derivatives of polyisobutylene (6. in Figure 9.1) offer the advantage of control over the molecular weight of the polyisobutylene obtained by cationic polymerization of isobutylene. Condensation on maleic anhydride can be done directly either by thermal activation ( ene-synthesis reaction) (2.1), or by chlorinated polyisobutylene intermediates (2.2). The condensation of the PIBSA on polyethylene polyamines leads to succinimides. Note that one can obtain mono- or disuccinimides. The mono-succinimides are used as... 

Molecular weights of polymers that function as bridging agents between particles are ca 10 —10. Ionic copolymers of acrylamide are the most significant commercially (see Acrylamide POLYMERS). Cationic comonomers include (2-methacryloyloxyethyl)trimethylammonium salts, diethyl aminoethyl methacrylate [105-16-8], and dimethyldiallylammonium chloride [7398-69-8], anionic comonomers include acryUc acid [79-10-7] and its salts. Both types of polyacrylamides, but especially the anionic, can be more effective in the presence of alum (10,11). Polyetbylenimine and vinylpyridine polymers, eg, po1y(1,2-dimethy1-5-viny1pyridiniiim methyl sulfa te) [27056-62-8] are effective but are used less frequentiy. 

The efficiency of flocculation of these polyelectrolytes was investigated at different pH and polymer concentrations, valency of cations, and weight-average molecular weight of the polymer. The results are shown in Figs. 12-16,... 

When the molecular weight of PS was decreased from 5.0 x 10 to (3.0-4.05) x 10, the abovementioned properties were also decreased in the presence of cationic catalysis after the destruction of PS. These predicted properties are related to the nature and the quantity of functional groups. 

Molecular ion (Section 12.1) The cation produced in the mass spectrometer by loss of an electron from the parent molecule. The mass of the molecular ion corresponds to the molecular weight of the sample. 

Kaneko et al. [80, 81] prepared copolymers of AA (93.9-95.9 mol%) and vinylbipyridine (1.6-3.7 mol%) with pendant Ru(bpy)2+ (2.4-2.5 mol%) (25). The quenching of the excited state of the pendant Ru(II) complex by MV2+ was accelerated in alkaline aqueous solution owing to the electrostatic attraction of the cationic quencher. Interestingly, the quenching efficiency was dependent on the molecular weight of 25. The quenching of the polymer with MW 2100 occurred... 

The surface and interfacial tension of a great number of ester sulfonates has been measured by Stirton et al. [26-28,30]. The values of the surface tension of 0.2% solutions at 25 °C are in the range from 25 to 50 mN/m and from 2 to 20 mN/m for the interfacial tension. In the group with the same number of C atoms the pelargonates and laurates have the lowest values. Among the esters of the same a-sulfo fatty acid, the surface and interfacial tension decreases with increasing molecular weight of the alcohols. Surface tension values also depend on the cation. For the alkali salts the values decrease from lithium to sodium to potassium. 

This novel enzyme was the only esterase able to release acetyl from sugar beet pectin and removed about 30% of the total acetyl groups present. It also caused the release of acetyl groups from a range of other acetylated substrates, either synthetic or extracted from plants, in small amounts. PAE had an apparent molecular weight of 60 kDa and showed optimal activity at pH 5.5 and a temperature of 50 C. The enzyme is sensitive to buffer composition and requires a bivalent cation for optimal activity and stability. In purified form this enzyme proved unstable, especially in phosphate buffers. 

---