Herstellung und antivirale Wirksamkeit von Polyacrylsäure und Polymethacrylsäure

The antiviral activity of a number of fractions of poly(acrylic acid)s and poly(methacrylic acid)s with different tacticities, different molecular weights and molecular weight distributions has been investigated. Isotactic poly(acrylic acid)s are essentially more antiviral active in the whole area of efficacy than the atactic ones. Independent of the tacticity poly(acrylic acid)s with molecular weights smaller than 5000 show no significant effects, polymers with molecular weights greater than 25000 are toxic in the used doses. The optimum of efficacy is between 6000 and 15000. Isotactic poly(acrylic acid)s with narrow molecular weight distributions are more active than those with broad distributions. The atactic poly(acrylic acid)s with lower efficacy do not show this relationship. Atactic poly(methacrylic acid)s are not antiviral active in vivo compared with untreated controls. Isotactic ones have a just detectable efficacy which is essentially lower than the activity of the atactic poly(acrylic acid)s.     

ABC triblock polyampholytes containing a neutral hydrophobic block,a polyacid and a polybase

Well defined ABC triblock copolymers of polystyrene-block-poly(2-vinylpyridine)-block-poly(tert-butyl methacrylate) and polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) were synthesized by sequential living anionic polymerization in tetrahydrofuran. Triblock copolymers with narrow molecular weight distribution were obtained. Hydrolysis of the poly(tert-butyl methacrylate) block yields polystyrene-block-polyvinylpyridine-block-poly(methacrylic acid) which demonstrates pH-dependent solution properties. Interpolymer complexation of the polyvinylpyridine and poly(methacrylic acid) blocks in the micellar solution is studied in dependence of the pH in solution by potentiometric, conductometric and turbidimetric titration, and in bulk by FTIR spectroscopy.     

Properties of liquid crystalline polymers in solution, 1. Determination of the molecular weight of polymethacrylates with mesogenic sidegroups

Derivatives of poly(methacrylic acid) with mesogenic sidegroups are aggregated in solution. Through structural changes which also take place in the solid state, the fraction of the aggregates increases with storage time. The formation of aggregates depends on temperature and occurs relatively slowly. In solution, the degree of aggregation strongly depends on the solvent. This aggregation leads to relatively high tacticity in products obtained by radical initiated polymerisations.     

Radical polymerization of methacrylic acid in the presence of poly(4-vinylpyridine) in methanol

The rate of radical polymerization of methacrylic acid (MA) was found enhanced in the presence of poly(4-vinylpyridine) (P4VP) of various molecular weights (M?_η) in methanol. The rate maximum shifted from 1 : 1 mole ratio of [P4VP]/[MA], based on the repeating units, to a larger polymer-monomer ratio and also the rate enhancement was smaller, when P4VP of smaller M?_η was used. The overall energy of activation was 36,1 and 60,7 kJ/mol in the presence and absence of P4VP, respectively. The M?_η of poly(methacrylic acid) (PMA) prepared with P4VP was about 10 times larger than the M?_η of PMA prepared without P4VP.     

Stereoregularity of poly(methacryloyl chloride) and poly(methacrylic salts) prepared by photopolymerization

Poly(methacryloyl chloride) (PMACl) and poly(methacrylic tetramethylammonium salts) and poly(methacrylic tetraethyl ammonium salts) (PMAAN⁺) have been prepared by radical photopolymerization at different temperatures. The obtained molecular weights are independent of the polymerization temperature in the range studied (+24 to ?30°C) which is in agreement with a purely photochemical process. The dependence of the tacticity upon temperature was examined by means of NMR spectroscopy. Deviations from Bernoullian statistics were confirmed. PMAAN⁺ salts prepared in water are highly syndiotactic and a nearly pure syndiotactic structure is obtained at +5°C. This behavior is explained by the repulsive interactions between the carboxylate anions promoting the racemic placement. The tacticity of PMACl is comparable with that of poly(methacryloyl fluoride). The structure is less syndiotactic and much more isotactic than that of poly(methyl methacrylate). This result is interpreted by considering the electron-withdrawing character of chlorine and fluorine atoms which affects the electronic structure and polarity of the carbonyl group near to the macroradical and competes with the preferential syndiotactic placement observed with α-substituted acrylates.     

Polymer-solvent interactions in mixed solvents, 3. Poly(methacrylic acid) and poly(sodium methacrylate) in water-dioxane mixtures

The preferential solvation of poly(methacrylic acid) and poly(sodium methacrylate) in waterdioxane mixtures was investigated by means of specific refractive index increment measurements on dialysed and undialysed solutions. The correlation with the solvent-induced conformational transition of poly(methacrylic acid) was also studied. Potentiometric titrations indicate that this transition occurs at around 25–30 vol.-% of dioxane. Comparison with previous results on poly(acrylic acid) and poly(sodium acrylate) in the same solvent system and on poly(methacrylic acid) in water-2-chloroethanol mixtures, shows differences in the mode of solvation of the compact conformation. It is suggested that this may be dependent on the existence of water-organic solvent specific interactions such as the formation of a water-dioxane hydrogen-bonded complex.     

Solid state polymerization of zinc methacrylate

Zinc methacrylate has been polymerized in the solid state by the post-irradiation technique at 89.5°C. The polymer produced was less isotactic than that obtained from barium methacrylate dihydrate when polymerized under similar conditions. The tacticity of the poly(zinc methacrylate) differed markedly from the polymer produced in the liquid phase from methyl methacrylate or methacrylic acid. X-ray studies of the zinc methacrylate showed the monomer to have an orthorhombic unit cell with lattice constants of a = 17.94Å, b = 9.16 Å, and c = 13.2 Å. There are 8 molecules per unit cell and the symmetry can be classified as either Pnam or Pna2. The anhydrous monomer shows pronounced thermal polymerization at 89.5°C and the radiation-induced reaction shows no measurable intensity dependency over a 6 fold change in dose rate.     

Solvent effect on the formation of poly(methacrylic acid)-poly(N-vinyl-2-pyrrolidone) complex through hydrogen bonding

An interpolymer complex can be obtained by mixing the solutions of poly(methacrylic acid) and poly(N-vinyl-2-pyrrolidone). Three phase changes were observed on increasing the initial polymer concentration: namely, a homogeneous solution, a precipitate, and a gel. Such interpolymer complex formations were examined in several protic and aprotic solvents. The obvious relationship between the complex formation and the dielectric constant of the solvent was eludicated. The effect of hydrophobic interactions on the complex formation was also discussed as well as the role of the α-methyl group of poly(methacrylic acid).     

Complex formation of polyampholyte with proton-accepting polymers through hydrogen bonding

Polyampholytes, copolymers of methacrylic acid and 2-dimethylaminoethyl methacrylate [C(MA-AM)x] of various composition, were synthesized. Their isoelectric points (pI) are in the range 5 < pH < 7. Undissociated methacrylic acid residues in the copolymers can interact with ether oxygens of poly(ethylene glycol) (PEG) and ketone groups of poly(N-vinyl-2-pyrrolidone) (PVPo) in the acidic pH region through hydrogen bonding. However, only copolymers having more than about 60 mol-% of methacrylic acid residues form complexes with PVPo and high molecular weight PEG. The composition of the obtained complexes is 1:1 (mole ratio of methacrylic acid residues of the copolymer to repeating units of PVPo and PEG).     

Darstellung und eigenschaften der koordinationsverbindungen von poly(vinylpyridin)en mit den chloriden von Ru,Rh und Pd

Insoluble coordination compounds of Ru, Rh, and Pd with amorphous polymers of 2-, 3- and 4-vinylpyridine and with isotactic and syndiotactic polymers of 2-vinylpyridine were prepared. The mole ratio between metal chloride and vinylpyridine monomeric unit in initial reaction mixtures and in the resulting coordination compounds was compared and the chemical composition of the latter was determined. The character of the isolated coordination compounds of poly(vinylpyridine) is discussed on the basis of the obtained data.     

Polymere Aminoschutzgruppen. Synthese von neuen poly[2-(N-vinylpyridinio)ethoxycarbonyl]-,2-(N-pyridinio)ethoxycarbonyl- und 2-(N-4-picolinio)ethoxycarbonyl-geschützten Aminoderivaten und kinetische Untersuchungen zur basisch induzierten Aminosäurefreisetzung

2-Bromoethoxycarbonyl modified amino acids were reacted with pyridine, 4-picoline and poly(4-vinylpyridine) to yield the corresponding 2-(N-pyridinio)ethoxycarbonyl derivatives as water-soluble amino-protecting groups. The kinetics and activation energies of basicly induced cleavage of the amino acids were investigated by ¹H NMR spectroscopy in a D₂O/NaOD medium. The polymeric salts were found to be more reactive than the low molecular weight pyridinium bromides because of electrostatic polymeric effects. Additionally, the kinetic measurements confirmed a E1cB mechanism for the cleavage of the urethane function. The formation of peptide bonds was performed in the case of poly[2-(N-4-vinylpyridinioethoxycarbonyl)]-protected amino acids in aqueous medium by water-soluble carbodiimides.     

Calorimetric study on the formation of polymer complexes through electrostatic interaction and hydrogen bonding

Polymer complexes were formed through electrostatic interaction in poly(methacrylic acid)-integral type polycation systems and hydrogen bonding in the poly(methacrylic acid)-poly(N-vinyl-2-pyrrolidone) system in several solvents. The composition of the polyelectrolyte complex was affected by the chemical properties of solvents, e.g., the dissociation of the component polyelectrolyte was interferred with decreasing the polarity of the solvent. The heats of mixing in case of the combination of poly(methacrylic acid)-poly(N-vinyl-2-pyrrolidone) were negative in N,N-dimethylformamide but they were positive in water. In polyelectrolyte complex systems, they could not be measured by reason of some experimental difficulties. These results indicate that solvation of the component polymers is very important to clarify the mechanism of the formation of polymer complexes.     

Kinetic study of the quaternization of tertiary amine as functional group in the poly(vinylpyridine) series with alkyl bromide

The reactivity of tert-amine groups was studied by quaternization of homopolymers and copolymers of 2-vinyl-, 2-methyl-5-vinyl- and 4-vinyl-pyridine with butyl bromide. The reactivity of the corresponding model compounds was taken as a reference: in this case second order kinetics is obeyed until complete reaction of the pyridine derivatives. If the pyridylethylene repeating unit is included in a statistical styrene/vinylpyridine copolymer (with a low content of pyridylethylene units), the kinetics are of second order too, except for the styrene/2-vinylpyridine copolymer. In this case the steric hindrance due to the position of the nitrogen atom is the preponderant factor. For homopolymers, in the case of the quaternization of poly(1-pyrid-4-ylethylene) [poly(4-vinylpyridine)] second order kinetics are observed, until the adjacent reactive groups are quaternized. In the case of poly[1-(6-methyl-3-pyridyl)ethylene] [poly(2-methyl-5-vinylpyridine)] a second order law is obeyed only until one of the ajacent groups is quaternized. For poly(1-pyrid-2-ylethylene) [poly(2-vinylpyridine)] steric hindrance effects govern strictly the behaviour of the functional group. These results were interpreted by introducing three individual velocity constants which were determined graphically.     

Polycondensation d'acides α-aminés par des systèmes iode-phosphites en présence de pyridine ou d'imidazole

Polymerization of free α-amino acids with a pair of reagents–an oxidizing agent (iodine) and a reducing agent (phosphonic acid esters)–was achieved in organic medium in the presence of pyridine or imidazole. A standard procedure leading to optically pure polypeptides with degrees of polymerization up to 50 could be established. Polymeric material was also obtained with a dipeptide as monomer. Some preliminary polymerizations with polyfunctional reagents such as poly(4-vinylpyridine), cyclodiphosphites, or polyphosphites were performed.     

Metachromasia of pinacyanol chloride induced by synthetic polyanions

The metachromasia of the cyanine dye pinacyanol chloride sharply depends on the nature of the polyanions the dye interacts with. The metachromatic spectra of the dye induced by polymethacrylate (only at polymer/dye mole ratios P/D>3), polyacrylate and poly(vinyl sulfate) are broad and multiple-banded; whereas the spectra are sharp and single-banded with poly(methacrylic acid) and polystyrenesulfonate as the chromotropes. Poly(methacrylic acid) and polystyrenesulfonate form compounds with the dye with 2:1 stoichiometry, whereas the polyanion-dye complexes with polyacrylate and poly(vinyl sulfate) as polyanions have 1:1 stoichiometry. This observed difference in the metachromasia of this dye has been discussed in terms of the differences in stoichiometry, flexibility and conformation of the polyanion chains.     

Influence of Tacticity on the Structure Formation of Poly(methacrylic acid) in Langmuir/Langmuir–Blodgett and Thin Films

A perfect isotactic poly(methacrylic acid) (it-PMAA) is synthesized and characterized by NMR spectroscopy. Surface pressure versus mean area per repeat unit (π−A) isotherms are recorded and compared with atactic poly(methacrylic acid) (at-PMAA). it-PMAA exhibits a π−A isotherm, indicating the formation of a stable Langmuir film. The isotherm has a characteristic pseudo-plateau at π of ≈11–14 mN  m⁻¹ attributed to the creation of worm-like entities confirmed by atomic force microscopy (AFM) in Langmuir–Blodgett (LB) films. These structures transform into spherical nanoparticles of ≈40 to 80 nm seen in LB films transferred at the end of the pseudo-plateau of the isotherm. Grazing incidence wide-angle X-ray scattering (GI-WAXS) shows a broad scattering signal (halo-like) at a q position of ≈11.12 nm⁻¹, revealing the amorphous nature of the nanoparticles. An ordered morphology, however, is observed in thin films prepared by precipitating it-PMAA from dimethylformamide (DMF) solution under vigorous stirring and coating them on a solid support. Optical microscopy (OM), AFM, and GI-WAXS reveal more details about the structure. Finally, various structural modifications of PMAAs are explained based on their tacticity and the subsequent hydrogen bonding effects between the carboxylic acid groups.     

Polymerization of 4-vinylpyridine in the presence of poly(4-vinyloxycarbonylphthalic anhydride)

The polymerization of 4-vinylpyridine ( 1 ) in the presence of poly(4-vinyloxycarbonylphthalic anhydride) ( 4 ) was studied. In this system the polymerization rate and the conversion of 1 were dependent on the amount of 4 added, and a light brown polymer complex was given as a polymerization product which was constituted of 1:1 of poly(4-vinylpyridine) ( 2 ) and 4 in mole ratio. 2 , separated from the polymer complex, had the same degree of polymerization as 4 . Thus, this system was concluded to be a typical matrix polymerization system.     

The use of low-molecular-weight model compounds in an investigation of polyelectrolytes, 2. Potentiometric properties of poly[(methacrylic acid)-co-(2-dimethylaminoethyl methacrylate)] and its quaternary ammonium salt

The potentiometric behaviour of two polyampholytes, poly[(methacrylic acid)-co-(2-dimethyl-aminoethyl metharylate)] and poly{(methacrylic acid)-co-[2-(methacryloyloxy)ethyltrimethyl-ammonium iodide]} is described. The dissociation constants of low-molecular-weight compounds modelling the structural units and diads of polyampholytes are reported, and effects of adjacentgroups on the potentiometric behaviour of the copolymers are discussed.     

Electroconductivity and viscosity of complexes of poly(vinylpyridines) with alkali metal salts in organic solvents

The complexation of poly(4-vinylpyridine) (1) , poly(2-methyl-5-vinylpyridine) (2) and poly(2-vinylpyridine) (3) with bromides, perchlorates and tetraphenylborates of alkali metals in organic solvents was investigated by means of electroconductivity, viscometry and nuclear magnetic resonance spectroscopy. The influence of the nature of the polymer, the low-molecular-weight salt and the solvent, salt and polymer concentration as well as the temperature on complexation was studied. The fraction of cations and that of polymer units bound were determined. The compositions of the complexes were found by means of viscometry. It was established that the mechanism of binding of the polymers with alkali metal salts is of the ion-dipole type.     

Formation of polyion complexes between polycarboxylic acids and polycations carrying charges in the chain backbone

The formation of polyion complexes in aqueous medium between polycations carrying charges in the chain backbone and poly(carboxylic acid)s, such as poly(methacrylic acid) (PMAA), poly(carboxylic acid) (PAA), and poly(itaconic acid) (PIA), were studied. It was found that polycations formed more stable complexes than their corresponding low molecular weight cations and that in addition to the chain length, dissociation constants and the hydrophobicity dominated the ability of the formation of a polyion complex. The compositions of the complexes between polycation and polycarboxylic acid were defined mainly by the degree of dissociation (α′) of the poly(carboxylic acid). From these results it is concluded that the complexes are formed by the cooperative interactions between two polymer chains which have charges of opposite sign and the structures of polyion complexes can accept reversible states like loops, ladders, and their intermediate shapes.