PVP-PAA

Fig. 15 Pulse irradiation of PVP (Kollidon) and PVP-PAA complexes at different unit molar ratios (UM = [PAA]/([PAA] + [PVP])) of carboxylic groups. Measurements were conducted at pH 10. Left Molecular weight as a function of the radiation dose. Right Radius of gyration as a function of the radiation dose. (Reprinted from [22], copyright 2009, with permission of Elsevier)...

The cross-linking of PVP-PAA complexes is influenced by the molecular weight of PAA. A higher Afw of PAA results in higher Mw values of the cross-linked complexes compared to those obtained with low Mw PAA. 

Most research into the study of dispersion polymerization involves common vinyl monomers such as styrene, (meth)acrylates, and their copolymers with stabilizers like polyvinylpyrrolidone (PVP) [33-40], poly(acrylic acid) (PAA) [18,41],poly(methacrylicacid) [42],or hydroxypropylcellulose (HPC) [43,44] in polar media (usually alcohols). However, dispersion polymerization is also used widely to prepare functional microspheres in different media [45, 46]. Some recent examples of these preparations include the (co-)polymerization of 2-hydroxyethyl methacrylate (HEMA) [47,48],4-vinylpyridine (4VP) [49], glycidyl methacrylate (GMA) [50-53], acrylamide (AAm) [54, 55], chloro-methylstyrene (CMS) [56, 57], vinylpyrrolidone (VPy) [58], Boc-p-amino-styrene (Boc-AMST) [59],andAT-vinylcarbazole (NVC) [60] (Table 1). Dispersion polymerization is usually carried out in organic liquids such as alcohols and cyclohexane, or mixed solvent-nonsolvents such as 2-butanol-toluene, alcohol-toluene, DMF-toluene, DMF-methanol, and ethanol-DMSO. In addition to conventional PVP, PAA, and PHC as dispersant, poly(vinyl methyl ether) (PVME) [54], partially hydrolyzed poly(vinyl alcohol) (hydrolysis=35%) [61], and poly(2-(dimethylamino)ethyl methacrylate-fo-butyl methacrylate)... 

The miscibility of the blends and complex can be probed at even smaller scale by carrying out the Tj measurement, in which the relaxation time, Tip , was determined by monitoring the decay in carbon signal intensities as a function of delay time. All the resonance peaks show a single-exponential decay and the logarithmic plot of resonance intensity vs. delay time t for the selected carbon (33 ppm) of pure PVP, PAA/PVP blend (1/1), and complex. Furthermore, it can be seen from Table 2 that the standard deviation can be ignored and the I/,/ values obtained for each sample can be considered to be the same. All these imply that all of the blends and the complex are intimately mixed on the I/,/ measurement scale. The homogeneity data are accurate down to the scale of 2 nm for the blends and... 

There are two dominant sets of signals in NMR C spectra of copolymers of DAAH with VM (Table 7), the values of chemical shifts (c.s.) of these sets, including the signals of configurational multiplets of dyads, virtually coinsiding with the values of the homopolymers (PAAM, PVP, PAA) chemical shifts. Besides, in carbon spectra of the copolymers there are low intensity triplet signals, corresponding to C3 and Ce atoms of the joint comonomer imits. This fact indicates, that copolymers contain blocks of VM units, divided by DAAH units. 

Polymer/Polymer Complexes. PVP complexes with other polymers capable of interacting by hydrogen-bonding, ion-dipole, or dispersion forces. For example mixing of PVP with poly(acryHc acid) (PAA) in aqueous solution results in immediate precipitation of an insoluble complex (113). Addition of base results in dismption of hydrogen bonding and dissolution (114—116). Complexes with a variety of poly-acids (117) and polyphenols (118) have been reported. The interest in compatibiHty on a molecular level, an interesting phenomenon rarely found to exist between dissimilar polymers, is favored by the abiHty of PVP to form polymer/polymer complexes. 

HDZ = hydrazine Igepal CO-520 = polyoxyethylene(5)nonylphenyl ether ISO = isooctane LAc = linoleic acid MA = methylamine MST = mesitylene Ni°(cod)2 = bis (r]4-l,5-cyclooctadiene) Ni(0) NMPyr = N-methylpyrrole OA = oleylamine OAc = oleic acid Oc = octane OcA = octylamine ODA = octadecylamine PAA = poly (acrylic add) PD = 2-pyrrolidone Igepal CA-520 = polyoxyethylene(5)isooctylphenyl ether PVP = polyvinylpyrrolidone Pyr = pyrrole RAc = ricinoleic acid ... 

In this work, we have chosen several systems stabilized through hydrogen bonds. The homopolymer is a polybase, i.e. PEO, PVME or PVP, and the copolymer is polyacrylic acid with various degrees of neutralization a, in which the acrylates are the non active groups. Complex formation is studied by potentiometry (because complexation induces a variation of the solution pH) and by viscometry and polarized luminescence which respectively give information about the macroscopic and local structure of the complex in solution. The influence of parameters such as the degree of neutralization of PAA a, the concentration ratio r - [polybase]/[PAA], the concentration and the molecular weight of polymers is examined. 

The gain in viscosity also depends on the nature of polymers. Mixtures of particularly high viscosity are obtained with the system PAA-800 OOO/PVP-900 000. For a PAA degree of neutralization of 10% a gain in viscosity of six hundred is reached (Figure 7). The value of a at the maximum of g is 10% for the PAA/PVP system whereas it is 5% for the PAA/PEO couple. 

Figure 7. Gain in viscosity, g, versus concentration ratio. System PAA-800 OOO/PVP-900 000. [PAA] - 0.1 unit mol/1.

The complexation power of the three polybases towards PAA was easily estimated from potentiometric results PVP > PVME > PEO. The mean stoichiometry of the polymer complex depends on the degree of neutralization of the polyacid, a. 

PAA, or poly(methacrylic acid), PMA. The complexes of PAA or PMA with PEG were described long ago. The fact that PVP forms strong, water insoluble complexes with PAA with the following structure ... 

PAA formed in template polymerization was found to he remarkably similar to the degree of polymerization of the PVP template as shown in Figure 4.3. 

For (a), hydroxypropyl cellulose (HPC) (6-8), poly(vinyl pyrrolidone) (PVP) (9,10), poly(acrylic acid) (PAA) (9), and poly(dimethyl siloxane) (PDMS) (11) are usually employed. Ober et al. reported that the copolymers of isobutylene/isoprene and various methacrylates, which have weak polarity, are appropriate stabilizers for... 

Gold nanoparticles can also be stabilized using polymers that do not have specific functional groups through physisorption. Among the possible stabilizers, the polymers used most often to stabilize Au NPs are the water soluble polymers poly(N-vinylpyrrolidone) (PVP), polyethylene glycol) (PEG), poly(vinyl pyridine), poly(vinyl alcohol) (PVA), poly(vinyl methyl ether) (PVME), and polyelectrolytes such as PAA, chitosan, polyethyleneimine (PEI) or poly(diallyl dimethylammonium) chloride (PDDA) [99]. 

Polymethylmethacrylate (PMMA) Polyisodecylmethacrylate Polyacrylic acid (PAA) Polyacrylamide (PAAm) Hydrolyzed polyacrylamide Glyoxylyzed polyacrylamide Polyisobutylene (PIB) Polyethyleneoxide (PEO) Polystyrene Polystyrenesulfonate Polyethylenimine (PEI) Polyvinylalcohol (PVA) Polyvinylpyrrolidone (PVP) Poly-cw-isoprene (PCIP)... 

Fig. 3. Fractionation of PVP-49 under complex formation with PAA. Dots — experimental data on the average compositions of fractions of the copolymer bound in a polycomplex with different quantities of PAA 19-20), curve — calculation from Eq. (19) with x = 1.65...

PAAm, poly(acryl amide) PAA, poly(acrylic acid) PHC, poly(hydroxycarboxylic acid) PVP, poly(W-vinyl-2-pyrolidone) PVA, poly(vinyl alcohol) Aam, acryl amide AN, acrylonitrile. 

Hydroxypropyl cellulose (HPC) Hydroxyethylcellulose (HEC) Methylcellulose (MC) Polvinyl alcohol (PVA) Polyacrylic acid (PAA) Poly (meth) acrylic acid ester (PMAA) Polyvinyl pyrrolidone (PVP) Polyethylene glycols (PEG) White wax... 

Compared to cyclopentadiene, 1,3-cyclooctadiene appears to be more selectively hydrogenated to cyclooctene, since hydrogenation of the cyclooctene produced may be depressed almost completely over selective palladium catalysts such as Pd-PVP-MeOH/NaOH74 and PAA- or CO-poisoned palladium.75 The maximum yields of cy-cloalkene obtained were higher with 1,3-cyclooctadiene than with cyclopentadiene or with 1,4- and 1,5-cyclooctadiene, as seen from the results in Table 3.13. The yields of cyclooctene were lower with a commercial 5% Pd-C or unpoisoned palladium. Over these unpoisoned catalysts the cyclooctene formed was further hydrogenated to cyclooctane, although in slower rates than the cyclooctadiene. 

The first mention of the a(x) dependence was in experimental work [265], The dielectric relaxation data of water in mixtures of seven water-soluble polymers was presented there. It was found that in all these solutions, relaxation of water obeys the CC law, while the bulk water exhibits the well-known Debye-like pattern [270,271], Another observation was that a is dependent not only on the concentration of solute but also on the hydrophilic (or hydrophobic) properties of the polymer. The seven polymers were poly(vinylpyrrolidone) (PVP weight average molecular weight (MW) = 10,000), poly (ethylene glycol) (PEG MW = 8000), poly(ethylene imine) (PEI MW = 500,000), poly(acrylic acid) (PAA MW = 5000), poly(vinyl methyl ether) (PVME MW = 90,000), poly(allylamine) (PA1A MW = 10,000), and poly(vinyl alcohol) (PVA MW = 77,000). These polymers were mixed with different ratios (up to 50% of polymer in solution) to water and measured at a constant room temperature (25°C) [265]. 

Fig. 9. Dependence of sedimentation constants (1) and intrinsic viscosities (2,3,4) of complex solutions on the composition of H20-DMS0, PAA-PVP (1,3), PMAA-PVP (2), PMMI-PVP (4). . >...

Nonreacting units are inert to their own and another chain (for example, PAA-VP/ St copolymer64 or PVP-MAA/MMA copolymer75 systems). 

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